Download pdf - Appl. Phys. Express Vol.1, No.1 (2008) 011101 First ... · Mitsuru Funato*, Takeshi Kondou, Keita Hayashi, Shotaro Appl. Phys. Express Vol.1, No.1 (2008) 011202Nishiura, Masaya Ueda,

��JSAPInternationalNo.18(July2008)

Appl. Phys. Express Vol.1, No.1 (2008) 011101

First Operation of AlGaN Channel High Electron Mobility TransistorsTakumaNanjo*,MisaichiTakeuchi1,2,MuneyoshiSuita,YujiAbe,ToshiyukiOishi,YasunoriTokuda,andYoshinobuAoyagi1,2

(ReceivedNovember1,2007;acceptedNovember6,2007;publishedonlineDecember28,2007)

AchannellayersubstitutionofawiderbandgapAlGaNforconven-

tionalGaNinhighelectronmobilitytransistors (HEMTs) isonepossible

methodofenhancingthebreakdownvoltageforhigherpoweropera-

tion.WiderbandgapAlGaN,however,shouldalso increasetheohmic

contactresistance.WeutilizedaSi ion implantationdopingtechnique

toachievesufficiently lowresistivesource/draincontacts,andrealized

thefirstHEMToperationwithanAlGaNchannellayer.Thisresultisvery

promising for the furtherhigherpoweroperationofhigh-frequency

HEMTs.[DOI:10.1143/APEX.1.011101]

AdvancedTechnologyResearchandDevelopmentCenter,MitsubishiElectricCorporation,Amagasaki,Hyogo661-8661,Japan1 NanoscienceDevelopmentandSupportTeam,RIKEN,Wako,Saitama351-0198,Japan2 DepartmentofElectronicsandAppliedPhysics,TokyoInstituteofTechnology,Yokohama

226-8502,Japan* E-mailaddress:[email protected]


Continuous-Wave Operation of Blue Laser Diodes Based on Nonpolar m-Plane Gallium NitrideMasashiKubota,KuniyoshiOkamoto,TaketoshiTanaka,andHiroakiOhta*


Thecontinuous-wave(cw)operationofm-planeInGaN-basedblue

(460nm)laserdiodes(LDs)hasbeenachieved.Thethresholdcurrentand

thecorrespondingthresholdcurrentdensitywere40mAand5.0kA/cm2,

respectively,witha459nmlasingwavelengthundercwoperation.The

electroluminescencepeakwavelengthshift inpulsedmodewasonly

10nm(58meV), fromspontaneousemission(at0.3mA)tostimulated

emission(at32mA),whichisextremelysmallwhencomparedwiththat

ofc-planeblueLDs.Thisisfirstclearexperimentaldemonstrationofthe

advantage in fabricatingnonpolar InGaN-basedLDsbeyondtheblue

region.[DOI:10.1143/APEX.1.011102]

ResearchandDevelopmentHeadquarters,ROHMCo.,Ltd.,Kyoto615-8585,Japan* E-mailaddress:[email protected]


Effects of Traps Formed by Threading Dislocations on Off-State Breakdown Characteristics in GaN Buffer Layer in AlGaN/GaN Heterostructure Field-Effect TransistorsAkihiroHinoki,JunjirohKikawa1,TomoyukiYamada1,TadayoshiTsuchiya1,ShinichiKamiya1,MasahitoKurouchi1,KenichiKosaka,TsutomuAraki,AkiraSuzuki1,2,andYasushiNanishi(ReceivedNovember6,2007;acceptedNovember16,2007;publishedonlineDecember28,2007)

Theoff-statebreakdowncharacteristicsofGaNlayerswithdifferent

thicknessesfrom0.2to2µmgrownbymetalorganicchemicalvapor

depositiononSiCsubstrateswerediscussedusingthespace-charge-

limitedcurrentconductionmechanism.Withdecreasingthicknessofthe

GaNlayer,theoff-statebreakdownvoltageincreased.Thetrapdensity

intheGaNlayerwasestimatedfromthetraps-filled-limitvoltage,which

determinedtheoff-statebreakdownvoltage.Wefoundthatthethus-

estimatedtrapdensity increasedwithdecreasingthicknessoftheGaN

layer.Ahigherdensityofthreadingdislocations inthethinnersamples

wasconfirmedbytransmissionelectronmicroscopyobservations.These

resultssuggestthatthetrapsformedbythethreadingdislocationsinflu-

encetheoff-statebreakdownvoltageoftheGaNlayer.

[DOI:10.1143/APEX.1.011103]

DepartmentofPhotonics,RitsumeikanUniversity,1-1-1Noji-Higashi,Kusatsu,Shiga525-8577,Japan1 R&DAssociationforFutureElectronDevices,1-1-1Noji-Higashi,Kusatsu,Shiga525-8577,

Japan2 ResearchOrganizationofScienceandEngineering,RitsumeikanUniversity,1-1-1Noji-

Higashi,Kusatsu,Shiga525-8577,Japan


Blue Laser Diodes Fabricated on m-Plane GaN SubstratesYuhzohTsuda,MasatakaOhta,PabloO.Vaccaro,ShigetoshiIto,ShuichiHirukawa,YoshinobuKawaguchi,YoshieFujishiro,YoshiyukiTakahira,YoshihiroUeta,TeruyoshiTakakura,andTakayukiYuasa(ReceivedOctober30,2007;revisedDecember11,2007;acceptedDecember15,2007;publishedonlineJanuary11,2008)

Blue laserdiodes (LDs)werefabricatedonm-planeorientedGaN

substratesbyatmospheric-pressuremetalorganicchemicalvapordeposi-

tion.Typicalthresholdcurrentforstimulatedemissionatawavelengthλ

of463nmwas69mA.Blueshiftofthespontaneousemissionpeakwith

increasinginjectioncurrentwasexaminedinLDsfabricatedonm-and

c-planeGaNsubstrates.Blueshiftsforthem-planeLD(λ=463nm)and

thec-planeLD(λ=454nm)withaninjectioncurrentdensity justbelow

thresholdwereabout10and26nm,respectively.Theseresultsconfirm

that theblueshift inquantum-wells fabricatedonm-planeoriented

substrates is smaller thanonc-planeorientedsubstratesdue to the

absenceofpolarization-inducedelectricfields.

[DOI:10.1143/APEX.1.011104]

AdvancedTechnologyResearchLaboratories,SharpCorporation,2613-1Ichinomoto-cho,Tenri,Nara632-8567,Japan

Applied Physics Express

JSAPInternationalNo.18(July2008)��


Vertical GaN-Based Trench Gate Metal Oxide Semiconductor Field-Effect Transistors on GaN Bulk SubstratesHirotakaOtake,KentaroChikamatsu,AtsushiYamaguchi,TatsuyaFujishima,andHiroakiOhta*

(ReceivedNovember5,2007;acceptedNovember12,2007;publishedonlineJanuary11,2008)

Completelyvertical trenchgatemetaloxidesemiconductor field-

effect transistors (MOSFETs)havebeenproducedusinggalliumnitride

(GaN)forthefirst time.TheseMOSFETsexhibitedenhancement-mode

operationwitha thresholdvoltageof3.7Vandanon-resistanceof

9.3mΩ·cm2.Thechannelmobilitywasestimatedtobe131cm2/(V·s)

whenall theresistancesexceptforthatofthechannelareconsidered.

Suchstructures,whichsatisfythekeywords“vertical”,“trenchgate”,

and“MOSFET”,willenableustofabricatepracticalGaN-basedpower

switchingdevices.[DOI:10.1143/APEX.1.011105]

ResearchandDevelopmentHeadquarters,ROHMCo.,Ltd.,Kyoto615-8585,Japan* E-mailaddress:[email protected]


Monolithic Polychromatic Light-Emitting Diodes Based on InGaN Microfacet Quantum Wells toward Tailor-Made Solid-State LightingMitsuruFunato*,TakeshiKondou,KeitaHayashi,ShotaroNishiura,MasayaUeda,YoichiKawakami,YukioNarukawa1,andTakashiMukai1(ReceivedNovember15,2007;acceptedDecember9,2007;publishedonlineJanuary17,2008)

Monolithicpolychromatic light-emittingdiodes (LEDs)basedon

micro-structured InGaN/GaNquantumwellsaredemonstrated.The

microstructureiscreatedthroughregrowthonSiO2maskstripesalong

the[11–00]directionandconsistsof(0001)and{112

–2}facets.TheLEDs

exhibitpolychromaticemission,includingwhite,duetotheadditivecolor

mixtureoffacet-dependentemissioncolors.Alteringthegrowthcondi-

tionsandmaskgeometryeasilycontrols theapparentemissioncolor.

Furthermore,simulationspredicthigh lightextractionefficienciesdue

totheir three-dimensionalstructures.Thoseobservationssuggest that

theproposedphosphor-freeLEDsmayleadtohighlyefficientsolid-state

lighting inwhichthecolorspectraof lightsourcesaresynthesizedto

satisfyspecificrequirementsforilluminations.

[DOI:10.1143/APEX.1.011106]

DepartmentofElectronicScienceandEngineering,KyotoUniversity,Kyoto615-8510,Japan1 NitrideSemiconductorResearchLaboratory,NichiaCorporation,Tokushima774-8601,

Japan* E-mailaddress:[email protected]


Germanium Nitride Interfacial Layer for Chalcogenide Random Access Memory ApplicationsJieShen1,2,*,BoLiu1,**,ZhitangSong1,ChengXu1,2,FengRao1,2,ShuangLiang1,2,SonglinFeng1,andBomyChen3


Thisworkreportsontheperformance improvementofachalco-

geniderandomaccessmemorydevicebyapplyinggermaniumnitrideas

aninterfacial layer.Thedevicewithan8-nm-thickGeNfilmwasfabri-

catedusingstandard0.18µmcomplementarymetaloxidesemiconductor

technology.Theas-depositedGeNis in theamorphousstateandhas

asmoothsurface.Anelectrical testshowedthatthisN-deficient layer

inducesalowerthresholdvoltageduringtheoperation.Itisbelievedthat

thereductionmainlyoriginatedfromtheexcellentinterfacialproperties,

highelectricalresistivity,andlowthermalconductivityofGeN,whichis

wouldbeaprospectiveinterfacialmaterialinCRAMdevices.

[DOI:10.1143/APEX.1.011201]

1 LaboratoryofNanotechnology,ShanghaiInstituteofMicrosystemandInformationTechnology,ChineseAcademyofSciences,Shanghai200050,P.R.China

2 GraduateUniversityofChineseAcademyofSciences,Beijing100039,P.R.China3 SiliconStorageTechnology,Inc.,1171SonoraCourt,Sunnyvale,CA94086,U.S.A.* E-mailaddress:[email protected]**E-mailaddress:[email protected]


Vertical Solar-Blind Deep-Ultraviolet Schottky Photodetectors Based on β-Ga�O� SubstratesTakayoshiOshima*,TakeyaOkuno,NaokiArai1,NorihitoSuzuki1,ShigeoOhira1,andShizuoFujita2


Avertical-typeSchottkyphotodetectorbasedona (100)-oriented

β-Ga2O3substratehasbeenfabricatedwithsimpleprocessesofthermal

annealingandvacuumevaporation.Thephotodetectorexhibitedarecti-

fication ratiohigher than106at±3V,andshoweddeep-ultraviolet-

lightdetectionatreversebias.Thespectralresponseshowedsolar-blind

sensitivitywithhighphotoresponsivitiesof2.6–8.7A/Watwavelengths

of200–260nm.Thesevalueswere35–150timeshigher thanthose

derivedassumingtheinternalquantumefficiencytobeunity.Thisfact

isattributedtothecarriermultiplicationoccurringinthehighlyresistive

surfaceregionthat issubject toahigh internalelectric fieldofabout

1.0MV/cmatthereversebiasof10V.[DOI:10.1143/APEX.1.011202]

DepartmentofElectronicScienceandEngineering,KyotoUniversity,Katsura,Nishikyo-ku,Kyoto615-8510,Japan1 NipponLightMetalCompany,Ltd.,Kambara,Shimizu-ku,Shizuoka421-3291,Japan2 GraduateSchoolofEngineering,KyotoUniversity,Katsura,Nishikyo-ku,Kyoto615-8520,

Japan* E-mailaddress:[email protected]



Current-Driven Domain Wall Motion in CoCrPt Wires with Perpendicular Magnetic AnisotropyHironobuTanigawa,KoutaKondou,TomohiroKoyama,KunihiroNakano,ShinyaKasai,NorikazuOhshima1,ShunsukeFukami1,NobuyukiIshiwata1,andTeruoOno(ReceivedNovember5,2007;acceptedNovember12,2007;publishedonlineJanuary11,2008)

We report thedirectobservationofcurrent-drivendomainwall

(DW)motioninaCoCrPtwirewithperpendicularmagneticanisotropy.

MagneticforcemicroscopyshowedthatasingleDWintroducedinthe

wireisdisplacedbackandforthbypositiveandnegativepulsedcurrent.

This is the firstdemonstrationof thecurrent-drivenDWmotion ina

metallicmagneticwirewithperpendicularmagneticanisotropy in the

absenceofamagneticfield.[DOI:10.1143/APEX.1.011301]

InstituteforChemicalResearch,KyotoUniversity,Uji,Kyoto611-0011,Japan1 DevicePlatformsResearchLaboratories,NECCorporation,1120Shimokuzawa,Sagamihara,

Kanagawa229-1198,Japan


On Effects of Gate Bias on Hole Effective Mass and Mobility in Strained-Ge Channel StructuresKentarouSawano,YugoKunishi,YuuSatoh,KiyohikoToyama1,KeisukeArimoto2,ToruOkamoto1,NoritakaUsami3,KiyokazuNakagawa2,andYasuhiroShiraki(ReceivedNovember6,2007;acceptedNovember25,2007;publishedonlineJanuary11,2008)

Theeffectsofgatebiasonholeeffectivemass(m*)andHallmobility

werestudiedinstrained-Gechannelmodulation-dopedstructures.Shub-

nikov–deHaasoscillationswereanalyzedwithandwithoutthebiasand

asignificantm* increasefrom0.15to0.22m0wasobservedwiththe

increase inthecarrierdensityduetothestrongnonparabolicityofthe

valenceband.This isacleardemonstrationthatmodificationofcarrier

densityviagatingconsiderablyaffectsm*,whichmayhavecriticaleffects

ondeviceproperties.ThegatebiasdependenceofHallmobilitywasalso

investigatedandthedominantscatteringmechanismwasclarified in

varioustemperatureandcarrierdensityregions.

[DOI:10.1143/APEX.1.011401]

ResearchCenterforSiliconNano-Science,AdvancedResearchLaboratories,MusashiInstituteofTechnology,8-15-1Todoroki,Setagaya-ku,Tokyo158-0082,Japan1 DepartmentofPhysics,UniversityofTokyo,7-3-1Hongo,Bunkyo-ku,Tokyo113-0033,

Japan2 CenterforCrystalScienceandTechnology,UniversityofYamanashi,7Miyamae-cho,Kofu

400-0021,Japan3 InstituteforMaterialResearch,TohokuUniversity,2-1-1Katahira,Aoba-ku,Sendai

980-8577,Japan


Piezoelectric Properties of (K,Na)NbO� Films Deposited by RF Magnetron SputteringKenjiShibata,FumihitoOka,AkioOhishi,TomoyoshiMishima,andIsakuKanno1(ReceivedNovember7,2007;acceptedDecember3,2007;publishedonlineJanuary11,2008)

High-piezoelectricity lead-free filmsof (K,Na)NbO3 (KNN)were

successfullydepositedonPt /MgOandPt / Ti / SiO2 /SisubstratesbyRF

magnetronsputtering.TheKNNfilmwasepitaxiallygrownonPt /MgO

withahigh<001>orientation in thepseudo-cubicperovskitestruc-

ture.TheKNNfilmonPt / Ti / SiO2 /Siwaspolycrystallinewithaprefer-

ential<001>orientation inthepseudo-cubicperovskitestructure.The

piezoelectricpropertiesoftheKNNfilmsweredeterminedfromthetip

displacementofKNN/Pt /MgOorKNN/Pt / Ti / SiO2 /Siunimorphcantile-

vers.Thetransversepiezoelectriccoefficientse31*(d31 /s11

E)oftheKNN

filmsonPt /MgOandPt / Ti / SiO2 /Siwerecalculatedtobe-3.6and-5.5C/

m2,respectively,whichareamongst thehighestvalues forKNNfilms

everreported.[DOI:10.1143/APEX.1.011501]

AdvancedElectronicMaterialsResearchDepartment,ResearchandDevelopmentLaboratory,HitachiCable,Ltd.,3550Kidamari,Tsuchiura,Ibaraki300-0026,Japan1 DepartmentofMicroEngineering,KyotoUniversity,Yoshida-honmachi,Sakyo-ku,Kyoto

606-8501,Japan


Valence State of Mn-Doped BiFeO� –BaTiO� Ceramics Probed by Soft X-ray Absorption SpectroscopyTohruHiguchi1,2,WataruSakamoto3,NaoyukiItoh3,TetsuoShimura3,TakeshiHattori2,andToshinobuYogo3

(ReceivedNovember16,2007;acceptedDecember3,2007;publishedonlineJanuary11,2008)

The valence state ofMn-dopedBiFeO3 –BaTiO3 ceramics has

beenprobedbysoftX-rayabsorptionspectroscopy (XAS).Mn-doped

BiFeO3 –BaTiO3hasvalencestatesofFe3+andTi4+,althoughBiFeO3

andMn-dopedBiFeO3havemixedvalence statesofFe2+andFe3+.

TheMn2p-XASpeakofMn-dopedBiFeO3 –BaTiO3 locatesata lower

energysidethanthatofMn-dopedBiFeO3thatcorrespondstotheMn3+

valencestate.ThesefindingsmayindicatethattheFe3+valencestateof

Mn-dopedBiFeO3 –BaTiO3isstabilizedbychargetransferfromtheMn

3dstatetotheFe3dstatethroughtheTi3dstateinBaTiO3.

[DOI:10.1143/APEX.1.011502]

1 AdvancedLightSource,LawrenceBerkeleyNationalLaboratory,1CyclotronRoad,MS7R0222,Berkeley,CA94720,U.S.A.

2 DepartmentofAppliedPhysics,TokyoUniversityofScience,1-3Kagurazaka,Shinjuku,Tokyo162-8601,Japan

3 EcoTopiaScienceInstitute,NagoyaUniversity,Furo-cho,Chikusa-ku,Nagoya464-8603,Japan




Superconductor-based Light Emitting Diode: Demonstration of Role of Cooper Pairs in Radiative Recombination ProcessesYujiroHayashi1,*,KazunoriTanaka2,3,TatsushiAkazaki3,4,MasafumiJo1,HidekazuKumano1,3,andIkuoSuemune1,3


A lightemittingdiodewith superconductingNbelectrodeswas

fabricatedto investigate thecontributionofcooperpairs toradiative

recombination inasemiconductor.Electroluminescenceobservedfrom

theactive layer inwhichelectroncooperpairsandnormalholesare

injectedwasdrasticallyenhancedat the temperature lower thanthe

superconductingtransitiontemperatureoftheNbelectrodes.Thisisthe

firstexperimentalevidencethatcooperpairsenhanceradiativerecombi-

nationsbythesuperradianceeffect.[DOI:10.1143/APEX.1.011701]

1 ResearchInstituteforElectronicScience,HokkaidoUniversity,Sapporo001-0021,Japan2 CentralLaboratory,HamamatsuPhotonics,Hiraguchi,Hamamatsu434-8601,Japan3 CREST,JapanScienceandTechnologyAgency,Kawaguchi,Saitama332-0012,Japan4 NTTBasicResearchLaboratory,Morinosato-Wakamiya,Atsugi,Kanagawa243-0198,Japan* E-mailaddress:[email protected]


Dual Self-Aligned Vertical Multichannel Organic TransistorsHidenoriNaruse,ShigekiNaka,andHiroyukiOkada*


Adual self-alignedverticalmultichannelorganic transistor (DSA-

VMCOT)isproposedanddemonstrated.Thelayoutsoftheshadowgate

and transparent source/drainaresequentiallydeterminedusingdual

back-surfaceexposure.Vertical100-nmchannelandmultichannelstruc-

turesareobtainedusinginterdigitalgateelectrodes.Thisdeviceconcept

ispromisingforuseasabackplanewithhighcurrentdrivingcapability.

[DOI:10.1143/APEX.1.011801]

GraduateSchoolofScienceandEngineering,UniversityofToyama,3190Gofuku,Toyama930-8555,Japan* E-mailaddress:[email protected]


Planar Avalanche Photodiode for Long-Haul Single-Photon Optic Fiber CommunicationsEijiYagyu*,KoheiSugihara,TsuyoshiNishioka1,MitsuruMatsui1,KiichiYoshiara,andYasunoriTokuda(ReceivedNovember2,2007;acceptedNovember20,2007;publishedonlineDecember28,2007)

Wepresentahigh-performanceplanarGaInAs/InPavalanchephoto-

diode(APD)forlong-haulsingle-photonopticfibercommunications,that

is,quantumcryptography.TheAPDsforsingle-photoncommunications

requireahighsingle-photondetectionefficiency(ηdet)relatingtobitrate

andalowratioofdarkcountprobability(Pdc)toηdetlimitingcommuni-

cationdistance.WefabricatedtheAPDwiththecombinationofalong

multiplicationregionlengthandalowcarriersheetdensityonthebasis

ofnumericalanalysis.ThePdc /ηdetmonotonicallydecreasedwithopera-

tiontemperaturelowered,andtheratioreached5.9×10-6withtheηdet

of13%at77K.ThePdcwas7.7×10-7,whichcorrespondstoadark

countrateof0.38kHz.TheusefulAPDandtheeffectivelayerdesignare

reported.[DOI:10.1143/APEX.1.012001]

AdvancedTechnologyR&DCenter,MitsubishiElectricCorporation,Amagasaki,Hyogo661-8661,Japan1 InformationTechnologyR&DCenter,MitsubishiElectricCorporation,Kamakura,Kanagawa



Two-Dimensional Photonic Crystal Composed of Ordered Polymer Nanopillar Arrays with High Aspect Ratios Using Anodic Porous Alumina TemplatesTakashiYanagishita1,*,KazuyukiNishio1,2,andHidekiMasuda1,2


Two-dimensional (2D)photonic crystals composedofordered

polymernanopillararrayswerefabricatedusinganodicporousalumina

templates.Forthepreparationof2Dphotoniccrystalswithhighaspect

ratios,polymerpillararrays, inwhichbothendsofnanopillarswere

supportedbysupportinglayers,wereintroduced.Thediameter,interval

and lengthofnanopillararrayscouldbecontrolledbychanging the

preparationconditionsofanodicporousaluminatemplates.Thereflec-

tionpropertiesoftheorderedpolymernanopillararrayobtainedexhib-

itedastopbandinthespectrum,whichcorrespondstothebandgapin

the2Dphotoniccrystals.[DOI:10.1143/APEX.1.012002]

1 KanagawaAcademyofScienceandTechnology,5-4-30Nishihashimoto,Sagamihara,Kanagawa229-1131,Japan

2 DepartmentofAppliedChemistry,TokyoMetropolitanUniversity,1-1Minamiosawa,Hachioji,Tokyo192-0397,Japan

* E-mailaddress:[email protected]


Tunable Liquid Crystal Laser Using Distributed Feedback Cavity Fabricated by Nanoimprint LithographyRyotaroOzaki,ToshikazuShinpo,KatsumiYoshino1,MasanoriOzaki2,andHiroshiMoritake(ReceivedNovember1,2007;acceptedNovember25,2007;publishedonlineJanuary11,2008)

Electricaltuningoflaserwavelengthisdemonstratedusingaliquid-

crystal /polymergrating fabricatedbynanoimprint lithography.Laser

emissionoccursatawavelengthnear700nm,whichcorrespondstothe

firstorderofa200nmperiodgrating.Withincreasingappliedvoltage,

thelasingspectrumbeginstoshifttoshorterwavelengthsat10V,and

thena10nmshiftisachievedwithanappliedvoltageof30V.Thisisdue

totherefractive indexchangeoftheliquidcrystal inthetrenchofthe

polymergratingbyfield-inducedmolecularreorientation.

[DOI:10.1143/APEX.1.012003]

DepartmentofElectricalandElectronicEngineering,NationalDefenseAcademy,1-10-20Hashirimizu,Yokosuka,Kanagawa239-8686,Japan1 ShimaneInstituteforIndustrialTechnology,1Hokuryo-cho,Matsue690-0816,Japan2 DivisionofElectrical,ElectronicandInformationEngineering,GraduateSchoolof

Engineering,OsakaUniversity,2-1Yamada-Oka,Suita,Osaka565-0871,Japan



Generation of Intense and Monochromatic Terahertz Radiation from Coherent Longitudinal Optical Phonons in GaAs/AlAs Multiple Quantum Wells at Room TemperatureMasaakiNakayama,Shuh-ichiIto,KohjiMizoguchi1,ShingoSaito2,andKiyomiSakai2(ReceivedNovember1,2007;acceptedDecember7,2007;publishedonlineJanuary11,2008)

Wehaveinvestigatedtime-domainsignalsofterahertz(THz)radia-

tion fromcoherent longitudinal-optical (LO)phonons inGaAs/AlAs

multiplequantumwellsatroomtemperature,utilizinganopticalgating

methodwithaphotoconductivedipoleantenna.Ithasbeenfoundthat

an intenseandmonochromaticTHzwavewithafrequencyof8.7THz

isgenerated fromcoherentGaAs-likeLOphononsunder thecondi-

tionthattheenergyspacingbetweenthefundamentalheavy-holeand

light-holeexcitonsistunedtotheLO-phononenergy.Thepump-energy

andpump-powerdependencesof theTHz-radiation intensity indicate

thattheimpulsiveinterferenceoftheheavy-holeandlight-holeexcitons

dominatesthegenerationprocess.[DOI:10.1143/APEX.1.012004]

DepartmentofAppliedPhysics,GraduateSchoolofEngineering,OsakaCityUniversity,Sugimoto,Sumiyoshi-ku,Osaka558-8585,Japan1 DepartmentofPhysicalScience,GraduateSchoolofScience,OsakaPrefectureUniversity,

Gakuen-cho,Naka-ku,Sakai599-8531,Japan2 NationalInstituteofInformationandCommunicationsTechnology,Koganei,Tokyo

184-8795,Japan


Development of Electrooptic Modulator for Advanced Ground-Based Gravitational Wave Telescopes Using Stoichiometric MgO-Doped LiNbO� CrystalsNoriakiOhmae*,KoheiTakeno1,ShigenoriMoriwaki,andNorikatsuMio(ReceivedNovember2,2007;acceptedNovember20,2007;publishedonlineJanuary11,2008)

Wehavedevelopedanelectroopticmodulator (EOM)usingstoi-

chiometricMgO-dopedLiNbO3 (MgO-dopedSLN)crystals,andevalu-

atedthisEOMforthephasecontrolofahigh-powerlaserwhosepower

isover100W.Wesucceededinthephasemodulationofa100Wlaser

withoutadecreaseinphasemodulationindex,duetoanonlinearoptical

effect,whichcanoccurwhenahigh-powerlaserbeamenterstheEOM.

Wealsoestimatedwavefrontdistortionscausedbypassingthroughthe

EOMwithaShack –Hartmannwavefrontsensor,andfoundthat the

additionalwavefrontdistortionwasnegligible.Thus,weconfirmedthat

MgO-dopedSLNcrystalsareasuitablematerialforuseinahigh-power

lasersystem.[DOI:10.1143/APEX.1.012005]

DepartmentofAdvancedMaterialsScience,UniversityofTokyo,5-1-5Kashiwanoha,Kashiwa,Chiba277-8561,Japan1 NationalInstituteofAdvancedIndustrialScienceandTechnology,1-2-1Namiki,Tsukuba,

Ibaraki305-8564,Japan* E-mailaddress:[email protected]


Visible Anisotropic Deformation of Chalcogenide Glass by Illumination of Linearly Polarized LightKeijiTanaka(ReceivedNovember2,2007;acceptedNovember25,2007;publishedonlineJanuary11,2008)

It has been discovered that illumination of linearly-polarized

bandgaplightproducesvisible-scaleanisotropicdeformationsinacova-

lentchalcogenideglassAs2S3.X-raydiffractionandRaman-scattering

measurementsfordeformingAs2S3flakesdetectnomicroscopicstruc-

turalchanges.Measurementsofopticaltorqueindeformingflakesand

comparativeexposureexperimentsforcrystallineAs2S3andamorphous

Sesuggest that theanisotropicdeformationoccurs throughradiation

force,photoinducedbirefringence,andphotoinducedfluidity.

[DOI:10.1143/APEX.1.012006]

DepartmentofAppliedPhysics,GraduateSchoolofEngineering,HokkaidoUniversity,Kita-ku,Sapporo060-8628,Japan


Kerr-Lens Mode-Locked Diode-Pumped Yb:YAG Laser with the Transverse Mode Passively StabilizedSadaoUemura*andKenjiTorizuka(ReceivedNovember5,2007;acceptedNovember27,2007;publishedonlineJanuary11,2008)

WehavedevelopedaKerr-lensmode-lockeddiode-pumpedYb:YAG

laser inwhichthe transversemode ispassivelystabilized.Themode-

lockingschemecanbeusedforvariousdiode-pumpedYb-dopedbulk

lasers.Thepulsedurationisasshortas100fs,which is toourknowl-

edgetheshortestpulseeverproducedfromanYb:YAGlaser.Thecenter

wavelengthandlaseroutputpowerare1051nmand151mW,respec-

tively.[DOI:10.1143/APEX.1.012007]

PhotonicsResearchInstitute,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),Central2,1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan* E-mailaddress:[email protected]


Realization of All-fiber Tunable Filter and High Optical Power Blocker Using Thinned Fiber Bragg Gratings Coated with Carbon NanotubesKienT.Dinh*,Yong-WonSong1,ShinjiYamashita1,andSzeY.Set2


Weproposeandcreateanovelstructureformedwiththinnedfiber

Bragggratingsandcarbonnanotubesutilizingtheiropticalabsorption

characteristics.WeshowthatthereflectionbandofthefiberBragggrat-

ingscanbeshiftedbycontrollingthein-lineopticalpower.Weusethe

structuretorealizetwoapplicationsnamelyanall-fibertunablefilterand

ahigh-optical-powerblocker.[DOI:10.1143/APEX.1.012008]

GraduateSchoolofFrontierSciences,UniversityofTokyo,Tokyo113-8656,Japan1 DepartmentofElectronicsEngineering,UniversityofTokyo,Tokyo113-8656,Japan2 AlnairLaboratoriesCorporation,Tokyo154-0005,Japan* E-mailaddress:[email protected]




Propagation of Terahertz Pulses on Coplanar Strip-lines on Low Permittivity Substrates and a Spectroscopy ApplicationShinjiYanagi,MasayukiOnuma,JiroKitagawa,andYutakaKadoya*


Theauthorshave investigated thepropagationcharacteristicsof

theterahertzelectricalpulsesonthecoplanarstrip-lines(CPSs)madeon

lowpermittivitysubstrates.Bytheuseofacommerciallyavailableplastic

whosepermittivity isabout2.3 in1–3THz, the radiation losscould

bemade low,andthe totalattenuationofabout0.2neper/mmwas

achievedat1THz.Asaresult,thespectrareaching3THzwithadynamic

rangeofabout60dBwererealizedevenafter the1mmpropagation.

UsingtheCPSdevice,aspectroscopyofbiotinpowderisdemonstrated

overafrequencyrangeupto2THz.[DOI:10.1143/APEX.1.012009]

GraduateSchoolofAdvancedSciencesofMatter,HiroshimaUniversity,1-3-1Kagamiyama,Higashihiroshima,Hiroshima739-8530,Japan* E-mailaddress:[email protected]


Tunneling Current–Voltage Characteristics of Graphene Field-Effect TransistorVictorRyzhii1,3,MaximRyzhii1,3,andTaiichiOtsuji2,3


Wedevelopananalyticaldevicemodelforagraphenefield-effect

transistor.Usingthismodel,wecalculateitscurrent–voltagecharacteris-

ticsatsufficientlyhighgatevoltageswhenan–p–n(p–n–p)lateraljunc-

tionisformedinthetransistorchannelandthesource–draincurrentis

associatedwiththeinterbandtunnelingthroughthisjunction.

[DOI:10.1143/APEX.1.013001]

1 ComputerSolidStatePhysicsLaboratory,UniversityofAizu,Aizu-Wakamatsu,Fukushima965-8580,Japan

2 ResearchInstituteforElectricalCommunication,TohokuUniversity,Sendai980-8577,Japan3 CREST,JapanScienceandTechnologyAgency,Tokyo107-0075,Japan


Growth of Single-Walled Carbon Nanotubes from Ceramic Particles by Alcohol Chemical Vapor DepositionHuapingLiu1,*,DaisukeTakagi1,HiroshiOhno1,ShoheiChiashi1,TomohitoChokan1,andYoshikazuHomma1,2,**

(ReceivedOctober27,2007;acceptedDecember10,2007;publishedonlineJanuary11,2008)

Al2O3ceramicnano-particles,whichwere regardedasan inac-

tivecatalyst inthegrowthofcarbonnanotubesinthepast,havebeen

preparedas thecatalyst forsingle-walledcarbonnanotube (SWCNT)

growthusinganalcohol chemical vapordepositionmethod.Dense

SWCNTshavebeensuccessfullysynthesized,indicatingthatAl2O3serves

asanefficientcatalyst.Moreover,itwasfoundthatmanySWCNTswere

alsogrownfrom irregular largeAl2O3particles ranging fromseveral

tensofnanometerstohundredsofnanometers,whichhasneverbeen

observedinthecaseofmetalliccatalystparticles.Theseresultsgivemore

insightsintotheroleofcatalystinSWCNTgrowth.

[DOI:10.1143/APEX.1.014001]

1 DepartmentofPhysics,TokyoUniversityofScience,Shinjuku,Tokyo162-8601,Japan2 CREST,JapanScienceandTechnologyAgency,Chiyoda,Tokyo102-0075,Japan* E-mailaddress:[email protected]**E-mailaddress:[email protected]


Behavior of Catalyst Particle at Tip of Carbon Nanotube during Field EmissionTadashiFujieda*,MakotoOkai,KishioHidaka,HiroakiMatsumoto1,andHiroshiTokumoto2


Acatalystparticleat the tipofamulti-walledcarbonnanotube

(MWNT)duringfieldemissioninsideatransmissionelectronmicroscope

wasobserved in-situ.Theparticlestreamedfromthetip likea liquid

astheemissioncurrentabruptly increasedfrom20to40µA.Thiswas

duetothetemperatureriseatthetipoftheMWNT,resultingfromthe

increasedemissioncurrentanddipolemomentintheparticlecausedby

theelectric field.Maintenanceof thishighemissioncurrent ledtoan

electricaldischarge,whichseverelydamagedtheMWNTelectronemitter.

Underhighemissioncurrents, inparticular,thecatalystparticlecaused

anunstableemission.[DOI:10.1143/APEX.1.014002]

MaterialsResearchLaboratory,Hitachi,Ltd.,Hitachi,Ibaraki319-1292,Japan1 HitachiHigh-TechManufacturingandServiceCorporation,Hitachinaka,Ibaraki312-0033,

Japan2 NanotechnologyResearchCenter,ResearchInstituteforElectronicScience,Hokkaido

University,Sapporo001-0021,Japan* E-mailaddress:[email protected]


Vapor–Liquid–Solid Growth of Small- and Uniform-Diameter Silicon Nanowires at Low Temperature from Si�H�SaeedAkhtar1,KoichiUsami1,YoshishigeTsuchiya1,2,HiroshiMizuta2,3,andShunriOda1,2,*


Wereport350°Casacriticalgrowthtemperatureforovercoming

theaggregationofgold (Au) in thesynthesisofhigh-density silicon

nanowires (SiNWs)withcontrolleddiameters inavapor – liquid–solid

(VLS)mechanismby the low-temperaturedecompositionofSi2H6.

Low-temperaturegrowthisconsideredessentialforpreservingtheinitial

distributionofAudroplets(8±5nm)duringSiNWnucleationwithsmall

(12nm)anduniform(±5nm)diameters.Au–Sieutecticsincreaseinsize

withaggregationathightemperatures,resultinginSiNWswithlargeand

randomdiameters.Thecrystalquality,defectformation,andmorphology

ofthewires,growninthe(111)direction,aresizedependent.

[DOI:10.1143/APEX.1.014003]

1 QuantumNanoelectronicsResearchCenter,TokyoInstituteofTechnology,2-12-1O-okayama,Meguro-ku,Tokyo152-8552,Japan

2 SolutionOrientedResearchforScienceandTechnology,JST,Kawaguchi,Saitama332-0012,Japan

3 SchoolofElectronicsandComputerScience,SouthamptonUniversity,Highfield,SouthamptonSO171BJ,U.K.




Development of �H–SiC Epitaxial Growth Technique Achieving High Growth Rate and Large-Area UniformityMasahikoIto*,LiutaurasStorasta,andHidekazuTsuchida(ReceivedNovember1,2007;acceptedNovember25,2007;publishedonlineJanuary11,2008)

Averticalhot-wallepi-reactorthatmakes itpossibletosimultane-

ouslyachieveahighgrowthrateand large-areauniformityhasbeen

developed.Amaximumgrowthrateof250µm/h isachievedwitha

mirror-likemorphologyat1650°C.Underamodifiedepi-reactorsetup,

athicknessuniformityof1.1%andadopinguniformityof6.7%fora

65-mm-radiusareaareachievedwhilemaintainingahighgrowthrate

of79µm/h.Alowdopingconcentrationof~1×1013cm-3isobtainedfor

a50-mm-radiusarea.The low-temperaturephotoluminescence (LTPL)

spectrumshowsthepredominanceoffreeexcitonpeakswithonlyfew

impurity-relatedpeaksandtheL1peakbelowdetectionlimit.Thedeep

leveltransientspectroscopy(DLTS)measurementforanepilayergrown

at80µm/hshowslowtrapconcentrationsofZ1/2:1.2×1012andEH6/7:

6.3×1011cm-3.A280-µm-thickepilayerwithaRMSroughnessof0.2nm

andacarrierlifetimeof~1µsisobtained.

[DOI:10.1143/APEX.1.015001]

CentralResearchInstituteofElectricPowerIndustry,2-6-1Nagasaka,Yokosuka,Kanagawa240-0196,Japan* E-mailaddress:[email protected]


High Mobility Titanium-Doped In�O� Thin Films Prepared by Sputtering/Post-Annealing TechniqueRyotaHashimoto,YoshiyukiAbe1,andTokioNakada(ReceivedNovember1,2007;acceptedDecember15,2007;publishedonlineJanuary17,2008)

High-electron-mobilityTi-dopedIn2O3(ITiO)thinfilmswereprepared

onsoda-limeglasssubstratesbyrfmagnetronsputteringfollowedbya

post-annealingprocess.Bothcarrierconcentrationandelectronmobility

wereconsiderablyimprovedbyannealinginavacuumat530°C.Ahighest

electronmobilityof105cm2V-1s-1witharesistivityof1.95×10-4 Ωcm

wasobtainedforanannealedITiOthinfilm.TheITiOthinfilmexhibited

anoptical transmissionofapproximately80%atwavelengthsranging

from400to1800nm.Post-annealinginavacuumisoneoftheeffective

methodsforimprovingtheelectricalpropertiesofITiOthinfilmswithout

sacrificingopticaltransmission.[DOI:10.1143/APEX.1.015002]

DepartmentofElectricalEngineeringandElectronics,AoyamaGakuinUniversity,5-10-1Fuchinobe,Sagamihara,Kanagawa229-8558,Japan1 IchikawaResearchLaboratory,SumitomoMetalMiningCo.,Ltd.,Nakakokubun,Ichikawa,

Chiba272-8588,Japan


Highly Sensitive Detection of Carbon Monoxide at Room Temperature Using Platinum-Decorated Single-Walled Carbon NanotubesWinaddaWongwiriyapan,SatoshiInoue,TatsuyaIto1,RyotaroShimazaki1,ToruMaekawa1,KengoSuzuki1,HiroshiIshikawa1,Shin-ichiHonda,KenjiroOura2,andMitsuhiroKatayama*


Wedemonstratedhighlysensitivedetectionofcarbonmonoxide(CO)

downto1ppmatroomtemperatureusingplatinum-decoratedsingle-

walledcarbonnanotubes(Pt-SWNTs).TheobtainedsensitivitytoCOwas

3–4ordershigherthanthevaluesreportedforfunctionalizedSWNTs,

andwasachievedbythecontrolleddepositionofPtnanoparticleson

SWNTs.For1–10ppmofCO, thesensor response linearly increased

withCOconcentration,affordingthequantitativedetectionofCOina

low-concentrationrange.Furthermore,Pt-SWNTsexhibiteddetection

selectivitytoCOagainstH2.Thesensingmechanismwasattributedto

electrondonationtotheSWNTsasaresultofCOoxidationonthePt

catalystsurface.[DOI:10.1143/APEX.1.014004]

DivisionofElectrical,ElectronicandInformationEngineering,GraduateSchoolofEngineering,OsakaUniversity,2-1Yamadaoka,Suita,Osaka565-0871,Japan1 NewCosmosElectricCo.,Ltd.,3-6-25Mitsuya-naka,Yodokawa-ku,Osaka532-0036,

Japan2 ResearchCenterforUltrahighVoltageElectronMicroscopy,OsakaUniversity,7-1

Mihogaoka,Ibaraki,Osaka567-0047,Japan* E-mailaddress:[email protected]


Local Synthesis of Tungsten Oxide Nanowires by Current Heating of Designed Micropatterned WiresKeisukeNagato1,2,*,YusukeKojima1,KeigoKasuya3,HirokiMoritani1,TetsuyaHamaguchi1,andMasayukiNakao1

(ReceivedDecember4,2007;acceptedDecember15,2007;publishedonlineJanuary17,2008)

We locally synthesized tungstenoxidenanowires atpredeter-

minedpositionsbycurrentheatingofdesignedmicropatternedwires.

Thecurrentwireswere fabricated from tungsten thin filmandhad

twodifferentwidthsinthesamewire,andthenarrowersectionswere

heatedmorethanthewidersectionsduetothedifference inelectric

resistance.The temperatureof thenarrowersectionswascontrolled

tobeoptimalfornanowiresynthesisinanO2atmosphereinavacuum

chamber.Wedemonstrated thesynthesisofnanowiresoveranarea

ofapproximately1×1µm2andsuccessfullysynthesizednanowiresona

regular20by20arraywithnarrowsectionswith10µmpitch.

[DOI:10.1143/APEX.1.014005]

1 DepartmentofEngineeringSynthesis,SchoolofEngineering,TheUniversityofTokyo,7-3-1Hongo,Bunkyo-ku,Tokyo113-8656,Japan

2 ResearchFellowoftheJapanSocietyforthePromotionofScience,8Ichibancho,Chiyoda-ku,Tokyo102-8472,Japan

3 CentralResearchLaboratory,Hitachi,Ltd.,1-280Higashi-koigakubo,Kokubunji,Tokyo185-8601,Japan





Photoluminescence from Epitaxial Films of Perovskite-type Alkaline-earth StannatesKazushigeUeda*,TsuyoshiMaeda,KensukeNakayashiki,KatsuhikoGoto,YutakaNakachi,HiroshiTakashima1,KenjiNomura2,KoichiKajihara2,**,andHideoHosono2


Theepitaxial filmsof the recentlydevelopedcalciumandstron-

tiumstannatesphosphorswithperovskiteor itsrelatedstructurewere

fabricatedby thepulsed-laseddepositionmethod.Thefilmswereall

highly transparent in thevisibleregion,andshowed intense lumines-

cenceofseveralcolorsunderultravioletexcitation.Lightscatteringat

thesubstrates'surfacesvariedtheappearanceofphotoluminescence.In

combinationwithepitaxial-film-growthtechnologiesformanyperovskite

functionalmaterials, theobtainedresultsprovideapromiseforfuture

developmentsofmultifunctionaloptoelectronicdevices.

[DOI:10.1143/APEX.1.015003]

KyushuInstituteofTechnology,1-1Sensui,Tobata,Kitakyushu804-8550,Japan1 NationalInstituteofAdvancedIndustrialScienceandTechnology,1-1-1Umezono,Tsukuba,

Ibaraki305-8568,Japan2 ERATO-SORST,JapanScienceandTechnologyAgency(JST),inFrontierCollaborative

ResearchCenter(FCRC),TokyoInstituteofTechnology,4259Nagatsuta,Midori,Yokohama226-8503,Japan

* E-mailaddress:[email protected]**Presentaddress:DepartmentofAppliedChemistry,GraduateSchoolofUrban

EnvironmentalSciences,TokyoMetropolitanUniversity,1-1Minami-Osawa,Hachioji,Tokyo192-0397,Japan.


Exciton-derived Electron Emission from (00�) Diamond p–n Junction Diodes with Negative Electron AffinityDaisukeTakeuchi1,*,ToshiharuMakino1,Sung-GiRi1,NorioTokuda1,HiromitsuKato1,MasahikoOgura1,HideyoOkushi1,2,andSatoshiYamasaki1,3


Electronemissioncurrentwasobserved fromahydrogen-termi-

natedn-layerdiamondsurfaceofforwardbiaseddiamondp–njunction

diodes,whiletherewasnoelectronemissionfromthesamesurfaceafter

oxidization,suggestingthatthephenomenonisrelatedtonegativeelec-

tronaffinity (NEA)ofthehydrogen-terminateddiamondsurface.Since

electronsinthen-layerflowtowardtothep-layerduetoforwardbias,

theycannotdirectlycontributetotheemissioncurrentfromthen-layer

surface. Inviewofourpreviousresult thattheexciton-derivedphoto-

electronemissionwasobservedfromtheNEAdiamondsurfacebytotal

photoelectronyieldspectroscopy,thephenomenoncanbeexplainedas

electronemissionduetoexcitondiffusionattheforwardbias.

[DOI:10.1143/APEX.1.015004]

1 NanotechnologyResearchInstitute,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan

2 SensorMaterialsCenter,NationalInstituteforMaterialsScience(NIMS),1-1Namiki,Tsukuba,Ibaraki305-0044,Japan

3 GraduateSchoolofPureandAppliedScience,UniversityofTsukuba,Tsukuba,Ibaraki305-8577,Japan



Molecular Layer-by-Layer Growth of C�0 Thin Films by Continuous-Wave Infrared Laser DepositionSeiichiroYaginuma1,2,KenjiItaka2,3,MasamitsuHaemori4,MasaoKatayama1,3,KeijiUeno5,TsuyoshiOhnishi6,MikkLippmaa6,YujiMatsumoto1,3,andHideomiKoinuma2,3,4,*


Theobservationofreflectionhighenergyelectrondiffraction(RHEED)

oscillationshasbeenproved tobeakey toopenthenano-worldof

materials, since itdefinitelyverifies that the filmgrowthproceeds in

layer-by-layermodewitheach layer thicknesscontrollableby simply

counting thenumberofoscillations.Thisenabled the fabricationof

nano-engineeredhetero-junctionsanddevicesascommonlypracticed

forconventionalsemiconductorsandmetals.Herewereportonthefirst

observationofclearRHEEDintensityoscillationinthinfilmfabricationof

aπ-conjugatedmolecularsolid.Theobservationhasbeenachievedby

couplinganoveldepositionmethodusingacontinuous-wave infrared

laserforevaporationandahighsensitiveRHEEDdetector,inadditionto

thecombinatorialoptimizationoffilmdepositionparametersthatfacili-

tatedourprecedingfirstsuccess inthe layer-by-layergrowthofoxide

thinfilms.Somedetailsofsystemdesignandexperimentalconditionsare

presentedtodiscussthekeyfactorsforatomicallycontrolledfilmgrowth

ofmolecularsolids.[DOI:10.1143/APEX.1.015005]

1 MaterialsandStructuresLaboratory,TokyoInstituteofTechnology,4259Nagatsuta,Midori-ku,Yokohama226-8503,Japan

2 GraduateSchoolofFrontierSciences,TheUniversityofTokyo,5-1-5Kashiwanoha,Kashiwa,Chiba277-8568,Japan

3 CREST,JapanScienceandTechnologyAgency(JST),4-1-8Honcho,Kawaguchi,Saitama332-0012,Japan

4 NationalInstituteforMaterialsScience,1-2-1Sengen,Tsukuba,Ibaraki305-0047,Japan5 DepartmentofChemistry,SaitamaUniversity,255Shimo-Okubo,Sakura-ku,Saitama

338-8570,Japan6 InstituteforSolidStatePhysics,TheUniversityofTokyo,5-1-5Kashiwanoha,Kashiwa,

Chiba277-8581,Japan* E-mailaddress:[email protected]


Selective-Area Growth of GaN Nanocolumns on Si(��) Substrates Using Nitrided Al Nanopatterns by RF-Plasma-Assisted Molecular-Beam EpitaxyShunsukeIshizawa1,2,KatsumiKishino1,2,*,andAkihikoKikuchi1,2


Theselective-areagrowthofGaNnanocolumnsusingpredeposited

Alnanopatterns(a300-nm-periodtriangular latticeof85-nm-diameter

Alnanodots)onSi(111)substratesbyrf-plasma-assistedmolecular-beam

epitaxy(rf-MBE)wasdemonstrated.GaNnanocolumnsweregrownat

theedgeofeachnitridedAldotafternitridation,formingananotubular

structure in thegrowth temperature range from941to966°C.The

sizefluctuationof thesidewall thickness in thenanotubularstructure

was lessthanthatofthediametersofnanocolumnsgrownontheSi

surfaceoutsidethenitridedAlnanopatterns.Atahighgrowthtempera-

tureof966°C,nanocolumngrowthontheSisurfacewascompletely

suppressed.[DOI:10.1143/APEX.1.015006]

1 DepartmentofElectricalandElectronicsEngineering,SophiaUniversity,Tokyo102-8554,Japan

2 CREST,JapanScienceandTechnologyAgency,Saitama332-0021,Japan* E-mailaddress:[email protected]

�0JSAPInternationalNo.18(July2008)


Improvement of Al-Polar AlN Layer Quality by Three-Stage Flow-Modulation Metalorganic Chemical Vapor DepositionMisaichiTakeuchi1,2,3,*,ShinOoishi2,TakumiOhtsuka2,TomohiroMaegawa2,TakahiroKoyama4,ShigefusaF.Chichibu4,andYoshinobuAoyagi1,2,3

(ReceivedDecember10,2007;acceptedJanuary9,2008;publishedonlineFebruary1,2008)

ImprovementofAl-polarAlN layerqualitywasaccomplishedby

three-stage flow-modulationmetalorganicchemicalvapordeposition

(FM-MOCVD).Inthismethod,theunitoftheFM-MOCVDsequencewas

composedofthreestages;StageIforsimultaneoussourcesupply,Stage

IIfortrimethylaluminumsupply,andStageIIIforammoniasupply,which

werecyclicallyrepeated.TheAlNqualityrevealedbyX-raydiffraction

stronglydependedonthetimeofStageI.Agrowthmodelwasproposed

consideringthesurfacecoverageoftheislandsnucleatedduringStage

I.Excitonfinestructureswereeventuallyobservedby low-temperature

cathodoluminescencereflectingthetremendously improvedcrystalline

quality.[DOI:10.1143/APEX.1.021102]

1 NanoscienceDevelopmentandSupportTeam,RIKEN,2-1Hirosawa,Wako,Saitama351-0198,Japan

2 DepartmentofElectronicsandAppliedPhysics,TokyoInstituteofTechnology,4259Nagatsuta,Midori-ku,Yokohama226-8503,Japan

3 RitsumeikanUniversity,1-1-1Noji-Higashi,Kusatsu,Shiga525-8577,Japan4 CenterforAdvancedNitrideTechnology(CANTech),InstituteofMultidisciplinaryResearch

forAdvancedMaterials(IMRAM),TohokuUniversity,2-1-1Katahira,Aoba,Sendai980-8577,Japan



AlGaN/GaN Heterostructure Field-Effect Transistors on �H-SiC Substrates with Current-Gain Cutoff Frequency of ��0GHzMasatakaHigashiwaki1,*,TakashiMimura1,2,andToshiakiMatsui1(ReceivedDecember26,2007;acceptedDecember28,2007;publishedonlineFebruary1,2008)

We reporton state-of-the-artAlGaN/GaNheterostructure field-

effecttransistor(HFET)technologyinthescopeofmillimeter-waveappli-

cations.60-nm-long-gateHFETshaving4-and6-nm-thickAl0.4Ga0.6N

barrier layersandSiNpassivation layers formedbycatalyticchemical

vapordeposition(Cat-CVD)werefabricatedon4H-SiCsubstrates.Both

structureshadlowsheetresistancesof200–220Ω / sqthatweredueto

notonlyhighmobilitiesof1900–2000cm2/(V·s)butalsohighelectron

densitiesof (1.4–1.7)×1013cm-2,whichwereprovidedbythehigh-Al-

compositionbarrierlayersandtheCat-CVDSiN.Thedeviceswiththe4-

and6-nm-thickbarriershadmaximumdraincurrentdensitiesof1.4and

1.6A/mmandpeakextrinsictransconductancesof448and424mS/mm,

respectively.MaximumfTandfmax reached190and251GHz,respec-

tively.[DOI:10.1143/APEX.1.021103]

1 NationalInstituteofInformationandCommunicationsTechnology,4-2-1Nukui-Kitamachi,Koganei,Tokyo184-8795,Japan

2 FujitsuLaboratoriesLtd.,10-1Morinosato-Wakamiya,Atsugi,Kanagawa243-0197,Japan* Presentaddress:DepartmentofElectricalandComputerEngineering,Universityof

California,SantaBarbara,SantaBarbara,CA93106,U.S.A. E-mailaddress:[email protected]


Thermal Stability of Giant Thermoelectric Seebeck Coefficient for SrTiO�/SrTi0.�Nb0.�O� Superlattices at �00KKyuHyoungLee1,*,YorikoMune2,HiromichiOhta1,2,**,andKunihitoKoumoto1,2


Hereinwe report thecarrier transportpropertiesof [(SrTiO3)x /

(SrTi0.8Nb0.2O3)1]20(x=0–50)superlatticesathightemperatures(T=300–

900K).Significantstructuralchangeswerenotobservedinthesuperlat-

ticesafterannealingat900Kinavacuum.TheSeebeckcoefficientof

the [(SrTiO3)20 / (SrTi0.8Nb0.2O3)1]20 superlattice,whichwas300µV·K-1

at room temperature, gradually increased with temperature and

reached450µV·K-1at900K,whichis~3timeslargerthanthatofbulk

SrTi0.8Nb0.2O3.Theseobservationsprovideclearevidencethatthesuper-

lattice is stableandexhibitsagiantSeebeckcoefficientevenathigh

temperature.[DOI:10.1143/APEX.1.015007]

1 CREST,JapanScienceandTechnologyAgency,4-1-8Honcho,Kawaguchi,Saitama332-0012,Japan

2 GraduateSchoolofEngineering,NagoyaUniversity,Furo-cho,Chikusa,Nagoya464-8603,Japan

* Presentaddress:AdvancedMaterialsLaboratory,SamsungAdvancedInstituteofTechnology,P.O.Box111,Suwon,Korea.

**E-mailaddress:[email protected]


Study on Injection Efficiency in InGaN/GaN Multiple Quantum Wells Blue Light Emitting DiodesLaiWang,JiaxingWang,HongtaoLi,GuangyiXi,YangJiang,WeiZhao,YanjunHan,andYiLuo*


Thedependenceoftheelectricalefficiencyontheinjectioncurrent

wasstudiedindetailinInGaN/GaNmultiplequantumwells(MQWs)blue

lightemittingdiodes.WhentheInGaNquantumwellthicknessincreased

from2to3.5nm,ortheAlcomponent inp-AlGaNchangedfrom0.1

to0.2,itwasfoundthattheelectricalefficiencydecreaseddramatically,

whileathinMg-dopedGaNlayerinsertedbetweenp-AlGaNandMQWs

withoptimizedMgconcentrationcanenhancetheelectricalefficiency

effectively.Analysisshowsthattheinjectionefficiencywasdramatically

affectedbytheinterfacestatesduetothestrongstressattheinterface

betweenp-AlGaNblockinglayerandMQWsactiveregionandthecapa-

bilityofelectronsarrivingattheinterface.

[DOI:10.1143/APEX.1.021101]

StateKeyLaboratoryonIntegratedOptoelectronics/TsinghuaNationalLaboratoryforInformationScienceandTechnology,DepartmentofElectronicEngineering,TsinghuaUniversity,Beijing100084,P.R.China* E-mailaddress:[email protected]




GaN-Based Trench Gate Metal Oxide Semiconductor Field-Effect Transistor Fabricated with Novel Wet EtchingMasahitoKodama*,MasahiroSugimoto1,EikoHayashi,NarumasaSoejima,OsamuIshiguro,MasakazuKanechika,KenjiItoh,HiroyukiUeda,TsutomuUesugi,andTetsuKachi(ReceivedDecember21,2007;acceptedJanuary24,2008;publishedonlineFebruary15,2008)

Anovelmethod for fabricating trench structuresonGaNwas

developed.A smoothnon-polar (11–00)planewasobtainedbywet

etchingusingtetramethylammoniumhydroxide(TMAH)astheetchant.

AU-shape trenchwith the (11–00)planesidewallswas formedwith

dryetchingandtheTMAHwetetching.AU-shapetrenchgatemetal

oxidesemiconductor field-effect transistor (MOSFET)wasalso fabri-

catedusingthenoveletchingtechnology.Thisdevicehastheexcellent

normally-offoperationofdraincurrent–gatevoltagecharacteristicswith

the thresholdvoltageof10V.Thedrainbreakdownvoltageof180V

wasobtained.Theresultsindicatethatthetrenchgatestructurecanbe

appliedtoGaN-basedtransistors.[DOI:10.1143/APEX.1.021104]

ToyotaCentralR&DLaboratories,Inc.,Nagakute-cho,Aichi480-1192,Japan1 ToyotaMotorCorp.,543Kirigahora,Nishihirose-cho,Toyota,Aichi470-0309,Japan* E-mailaddress:[email protected]


Epitaxial Lift-Off of InGaAs/InAlAs Metamorphic High Electron Mobility Heterostructures and Their van der Waals Bonding on AlN Ceramic SubstratesYonkilJeong,MasanoriShindo,MasashiAkabori*,andToshi-kazuSuzuki**


Wehave carried out epitaxial lift-off (ELO) of In0.57Ga0.43As/

In0.56Al0.44Asmetamorphichighelectronmobilityheterostructuresand

theirvanderWaalsbonding (VWB)onAlNceramicsubstrates.Using

ametamorphicheterostructurewithanAlAssacrificial layerandan

InGaAsgradedbuffergrownonGaAs(001), thinfilmHall-bardevices

onAlNceramic substrateswere successfully fabricatedbyELOand

VWB.TheHall-bardevicesexhibitveryhighelectronmobilities,suchas

11000cm2/(Vs)atroomtemperature (RT)and84000cm2/(Vs)at12K.

TheRTmobilityisthehighesteverreportedforELOdevices.Thisisthe

firstreportonELOformetamorphicdevices.

[DOI:10.1143/APEX.1.021201]

CenterforNanoMaterialsandTechnology,JapanAdvancedInstituteofScienceandTechnology(JAIST),1-1Asahidai,Nomi,Ishikawa923-1292,Japan* Presentaddress:InstituteofBio-andNanosystems(IBN-1),ResearchCentreJuelich,52425

Juelich,Germany.**E-mailaddress:[email protected]


Tunnel Magnetoresistance Effect in Magnetic Tunnel Junctions Using a Co�MnSi(��0) ElectrodeMasashiHattori,YuyaSakuraba,MikihikoOogane,YasuoAndo,andTerunobuMiyazaki(ReceivedDecember20,2007;acceptedDecember28,2007;publishedonlineFebruary1,2008)

Magnetic tunnel junctions (MTJs)withhalf-metallic electrodes

areexpected toshowa large tunnelmagnetoresistance (TMR) ratio,

accordingtoJulliere'smodel.ACo2MnSiHeusleralloy is theoretically

expectedtopossessahalf-metallicelectronicstate.Experimentally,at

low temperature,Co2MnSi(100)/Al-oxide/CoFe junctionsexhibiteda

largeTMRratio.WefabricatedMTJswithhigh-quality (110)-oriented

Co2MnSielectrodesand investigatedtheTMReffects.Weobtaineda

TMRratioofabout40%atroomtemperatureand120%at2K,respec-

tively.However,weobserveddegradationoftheenergygapofCo2MnSi

intheminorityspinbandfromtheconductance–voltagecharacteristics.

WeinferthattheinterfaceofCo2MnSi(110)possessesnohalf-metallic

property.[DOI:10.1143/APEX.1.021301]

DepartmentofAppliedPhysics,GraduateSchoolofEngineering,TohokuUniversity,Aoba-ku,Sendai980-8579,Japan


Enhanced Interlayer Coupling and Magnetoresistance Ratio in Fe�Si/FeSi� SuperlatticesKaoruTakeda,TsuyoshiYoshitake*,YoshikiSakamoto,TetsuyaOgawa,DaisukeHara,MasaruItakura,NoriyukiKuwano,ToshinoriKajiwara1,andKunihitoNagayama2

(ReceivedJanuary8,2008;acceptedJanuary18,2008;publishedonlineFebruary8,2008)

[Fe3Si / FeSi2]20superlatticeswerepreparedonSi(111)atanelevated

substratetemperatureof300°C,andthemagnetoresistanceratioand

interlayercouplingstrengthswereenhancedbyapproximately100and

34%,respectively,ascomparedtothoseofsuperlatticesdepositedat

roomtemperature.Whiletheelevatedsubstratetemperaturedegraded

theinterfacesharpness,thecrystallineorientationandthecrystallinityof

theFe3Silayerswereapparentlyenhanced.Thelattersstronglyinfluence

ontheinterlayercouplingandthemagnetoresistanceratio.Thisimplies

thatquantumwellstatesaretightlyformedunderthewell-orderedcrys-

tallineplanes,andthespindiffusion lengthsare improvedduetothe

enhancedcrystallinity.[DOI:10.1143/APEX.1.021302]

DepartmentofAppliedScienceforElectronicsandMaterials,KyushuUniversity,6-1Kasuga,Fukuoka816-8580,Japan1 DepartmentofElectricalEngineering,FukuokaInstituteofTechnology,Higashi-ku,Fukuoka

811-0295,Japan2 DepartmentofAeronautics,KyushuUniversity,Nishi-ku,Fukuoka819-0395,Japan* E-mailaddress:[email protected]



Quantitative Evaluation of Silicon Displacement Induced by Arsenic Implantation Using Silicon Isotope SuperlatticesYasuoShimizu,MasashiUematsu,KoheiM.Itoh*,AkioTakano1,KentarouSawano2,andYasuhiroShiraki2(ReceivedNovember21,2007;acceptedDecember28,2007;publishedonlineJanuary25,2008)

Weestablishedanewmethod forevaluatingquantitatively the

siliconatomicdisplacementasafunctionofthedepthfromthesurface

inducedbyarsenicimplantationintoasiliconwafer.Asimulationbased

onaconvolutionintegralwasdevelopedsuccessfullytoreproducethe

experimentaldepthprofilesofisotopesinthearsenic-implanted28Si / 30Si

isotopesuperlattices, fromwhich theaveragedistanceof thesilicon

displacementsduetothecollisionswith implantedarsenic isobtained.

Weshowthatittakestheaveragedisplacementof~0.5nmtomakethe

structureappearamorphousbytransmissionelectronmicroscopy.

[DOI:10.1143/APEX.1.021401]

DepartmentofAppliedPhysicsandPhysico-Informatics,KeioUniversity,3-14-1Hiyoshi,Kohoku-ku,Yokohama223-8522,Japan1 NTTAdvancedTechnologyCorporation,3-1Morinosato-Wakamiya,Atsugi,Kanagawa

243-0124,Japan2 ResearchCenterforSiliconNano-Science,AdvancedResearchLaboratories,Musashi

InstituteofTechnology,8-15-1Todoroki,Setagaya-ku,Tokyo158-0082,Japan* E-mailaddress:[email protected]


Room-temperature Transport Properties of High Drift Mobility Two-dimensional Electron Gas Confined in a Strained Si Quantum WellMaksymMyronov,KentarouSawano,KoheiM.Itoh1,andYasuhiroShiraki(ReceivedDecember1,2007;acceptedDecember18,2007;publishedonlineJanuary25,2008)

Thedriftmobility,carrierdensityandconductivityofthetwo-dimen-

sionalelectrongas (2DEG)confined in the tensilelystrained15nmSi

quantumwell(QW)ofSiGeheterostructureswereobtainedbymobility

spectrumanalysisatroom-temperature.Thehighest2DEGdriftmobility

of2900cm2V-1s-1withcarrierdensityof1×1011cm-2wereobserved

intheSiQWwith-0.9%tensilestrain.However,theincreaseofstrain

upto-1.08%resulted inthedeclineof2DEGdriftmobilitydownto

2670cm2,V-1s-1andthepronounced increaseofcarrierdensityupto

4.4×1011cm-2.Nevertheless, thepronouncedenhancementof2DEG

conductivitywasobserved.[DOI:10.1143/APEX.1.021402]

AdvancedResearchLaboratories,MusashiInstituteofTechnology,8-15-1Todoroki,Setagaya-ku,Tokyo158-0082,Japan1 DepartmentofAppliedPhysicsandPhysico-Informatics,KeioUniversity,Yokohama

223-8522,Japan


Improved Room-Temperature �.�µm Electroluminescence from p-Si/β-FeSi�/n-Si Double Heterostructures Light-Emitting DiodesMitsushiSuzuno,ShigemitsuMurase,TomoakiKoizumi,andTakashiSuemasu(ReceivedJanuary21,2008;acceptedJanuary27,2008;publishedonlineFebruary15,2008)

Wehaveepitaxiallygrownp-Si /β-FeSi2 /n-Sidoubleheterostructures

light-emittingdiodes (LEDs)onSi(111)substratesbymolecular-beam

epitaxy.The1.6µmelectroluminescence intensitymeasuredat room

temperature(RT)wasimprovedsignificantlyforLEDsconstructedusing

athickβ-FeSi2activelayer(190nm)embeddedinheavily-dopedSip–n

diodesformedonfloating-zoneSi(111)substrates.Theexternalquantum

efficiencywasincreaseduptoapproximately0.02%atRT.

[DOI:10.1143/APEX.1.021403]

InstituteofAppliedPhysics,UniversityofTsukuba,1-1-1Tennohdai,Tsukuba,Ibaraki305-8573,Japan


Un-stability of Sputtered Ge�Sb�Te� Films in Electrical Phase ChangesAkiraSaitoh,ToshiakiDonuma,andKeijiTanaka(ReceivedDecember11,2007;acceptedDecember22,2007;publishedonlineJanuary25,2008)

MicroscopicstructuresofamorphousGe2Sb2Te5 films,electrically

phase-changedusingco-planarelectrodes,havebeenstudiedthrough

electricalandstructuralinvestigations.Microscopeimagesshowastruc-

turedphase-changeregionconsistingofanarrowchannel,bankson

bothsides,androughperipheralregions.Theroom-temperatureresis-

tivity is~10-3Ω·cm,whichhasametallic temperaturedependence.

Micro-Ramanscatteringspectraat thechanneland thebankexhibit

peaksduetocrystallineTeandtellurides.X-raydiffractionpatternsfrom

thefilms,whichcontainmanychannels,presentcrystallinepeaksascrib-

abletocubicGeTeandothercompounds.Theseobservationssuggest

thattheGe2Sb2Te5meltisliabletophase-separateunderelectricalself-

heating.[DOI:10.1143/APEX.1.021501]

DepartmentofAppliedPhysics,GraduateSchoolofEngineering,HokkaidoUniversity,Sapporo060-8628,Japan


Improvement of Superconductive Properties of Mesoscopic Nb Wires by Ti Passivation LayersKoheiOhnishi1,TakashiKimura1,2,andYoshichikaOtani1,2

(ReceivedDecember17,2007;acceptedDecember28,2007;publishedonlineFebruary1,2008)

Wehave investigated superconductivepropertiesofnano-scale

Nbwires fabricatedbyasimple lift-offprocesswithmagnetronsput-

tering.Thesuperconductivepropertiesof theNbwireswereremark-

ablyimprovedbyemployinghighlyplasmaresistantelectron-beamresist

ZEP520AcombinedwithathinTipassivationlayer.Thisoptimizedfabri-

cationprocessyieldeda300-nm-wideNbwirewiththesametransition

temperatureasthatofthereferenceNbfilm.Thereby,ahighlytrans-

parentNb/Cujunctionwassuccessfullyfabricated.

[DOI:10.1143/APEX.1.021701]

1 InstituteforSolidStatePhysics,UniversityofTokyo,5-1-5Kashiwanoha,Kashiwa,Chiba277-8581,Japan

2 FrontierResearchSystem,RIKEN,2-1Hirosawa,Wako,Saitama351-0198,Japan




MgB� Thin Films Fabricated by a Precursor and Post-annealing Method Have a High Jc in High Magnetic FieldsAkiyoshiMatsumoto,YukiKobayashi,Ken-ichiroTakahashi,HiroakiKumakura,andHitoshiKitaguchi(ReceivedDecember26,2007;acceptedJanuary15,2008;publishedonlineFebruary1,2008)

Thecriticalcurrentdensities (Jc)ofMgB2 thin filmsdepositedon

α-Al2O3fabricatedbyaprecursorandpost-annealingprocesshavebeen

investigatedinhighmagneticfieldsofupto30T.Jcvaluesof2.8×105,

3.0×104,and3.7×103A/cm2wereobtainedat4.2Kinexternalmagnetic

fieldsof10,20,and26Trespectively,appliedparalleltothefilmsurface.

ThesevalueswerecomparabletothoseseenforNb3Sninfieldsupto

18T,andsurpassedtheminfieldsover18T.Thesuperconductingtran-

sitiontemperaturewasTconset=29.6KandTc

zero=28.5K.Grainconnec-

tivitywasestimatedtobe38.4%.TheHc2(0)estimatedfromtheresis-

tivitymeasurementswas45T.Transmissionelectronmicroscope(TEM)

observationsof themicrostructuressuggested thatgrains10 –20nm

insizeexistthatshownoepitaxialgrowthrelationshiptothesapphire

substrate.Jcenhancements infieldsupto~26Tareduetothestrong

grainboundarypinningassociatedwiththesmallgrainsandthesmall

sizeofMgOprecipitates.[DOI:10.1143/APEX.1.021702]

NationalInstituteforMaterialsScience,1-2-1Sengen,Tsukuba,Ibaraki305-0047,Japan


Characterization of Depletion Layer using Photoluminescence TechniqueVipulSingh*,AnilK.Thakur,ShyamS.Pandey,WataruTakashima,andKeiichiKaneto(ReceivedNovember19,2007;acceptedDecember18,2007;publishedonlineJanuary25,2008)

Thedepletionlayerformedatthe interfaceofaluminum(Al)with

poly(3-hexylthiophene-2,5-diyl)(P3HT)hasbeenstudied,usingthebias

dependentphotoluminescence (PL) spectra in indiumtinoxide (ITO)/

P3HT/Al sandwichedcells.Aquenching in thePL intensityhasbeen

observedunderthereversebiasconditions,whichhasbeenattributedto

theincreaseinthedepletionlayerwidth.Adirectrelationshipbetween

thedepletionlayerwidthandthePLquenchinghasbeenderivedand

explained.[DOI:10.1143/APEX.1.021801]

GraduateSchoolofLifeSciencesandSystemsEngineering,KyushuInstituteofTechnology,2-4Hibikino,Wakamatsu-ku,Kitakyushu808-0196,Japan* E-mailaddress:[email protected]


Improvement of Hole Mobility in Organic Field-Effect Transistors Based on Octyl-substituted Oligo-p-phenylenevinylene by Thermal Treatment at Smectic Liquid Crystalline PhaseHiroakiNakamura*,MasatoshiSaito,TadashiKusumoto,TakeshiYasuda1,2,andTetsuoTsutsui1(ReceivedDecember7,2007;acceptedDecember15,2007;publishedonlineJanuary25,2008)

Organicfield-effecttransistorsbasedonoctyl-subustitutedoligo-p-

phenylenevinylenehavebeenstudied.Wehavesucceededinimproving

field-effectholemobilitiesbythermaltreatmentatliquidcrystallinephase

characterizedasahighlyorderedsmecticphase.Thefield-effectmobility

ofthedeviceasvacuum-evaporatedwascalculatedtobe6.9×10-3cm2

V-1s-1whereasthemobilitywasenhancedto1.7×10-1cm2V-1s-1after

annealingthedeviceat100°Cfor12h.Fromthesurfacemorphology

ofthefilmsobservedbyusingatomicforcemicroscope,theenhance-

mentisfoundtobeattributedtoreductionofdefectdensityinthefilm

becauseof the thermalmovementof liquid-crystalmolecules. [DOI :

10.1143/APEX.1.021802]

CentralResearchLaboratories,IdemitsuKosanCo.,Ltd.,Sodegaura,Chiba299-0293,Japan1 DepartmentofAppliedScienceforElectronicsandMaterials,GraduateSchoolof

EngineeringSciencesandInstituteforMaterialChemistryandEngineering,KyushuUniversity,Kasuga,Fukuoka816-8580,Japan

2 PRESTO,JapanScienceandTechnologyAgency,Chiyoda-ku,Tokyo102-0075,Japan* E-mailaddress:[email protected]


Complementary Two-input NAND Gates with Low-voltage-operating Organic Transistors on Plastic SubstratesJongHoNa1,*,MasatoshiKitamura2,andYasuhikoArakawa1,2

(ReceivedNovember19,2007;acceptedJanuary9,2008;publishedonlineFebruary1,2008)

Wefabricatedtwo-inputNANDgatescomposedofp-channelpenta-

ceneandn-channelC60transistors.Thelogicdeviceswerepreparedon

flexiblepolymersubstrates throughashadowmaskprocess.Correct

NAND logic functionalitywasdemonstratedatawidevoltagerange

of2–7V.FromvoltagetransfercharacteristicsoftheNANDgates,we

obtainedimpressivesignalgainsupto120andlargenoisemargins in

thegivenvoltagerange.[DOI:10.1143/APEX.1.021803]

1 ResearchCenterforAdvancedScienceandTechnology,UniversityofTokyo,4-6-1Komaba,Meguro-ku,Tokyo153-8904,Japan

2 InstituteforNanoQuantumInformationElectronics,UniversityofTokyo,4-6-1Komaba,Meguro-ku,Tokyo153-8904,Japan




Whitening of Polymer Light-Emitting Diodes by Dispersing Vapor of an Orange Fluorescent Dye into a Blue-Emitting Polymer FilmToshikoMizokuro*,ClaireHeck,NobutakaTanigaki,TakashiHiraga,andNorioTanaka1


Whiteningofpolymer light-emittingdiodes (PLEDs)basedonthe

blue-emittingpoly(9,9-dioctylfluorene) (PDOF) filmswaspossibleby

dispersingvaporofanorangefluorescentdye4-(dicyanomethylene)-

2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) into the filmby

meansofthesolution-freevaportransportationmethod(VTM).Devices

preparedwiththismethodshowedgoodcolorstabilitywithbiasvoltage

increase,whilethoseformedwithconventionalspin-coating,wheredyes

andpolymersweremixedinasolution(solution-mixed),showedcolor

changefromyellowtowhite-yellow.Themaximumluminanceof the

PLEDformedbytheVTMwashigherthanthatformedbyconventional

spin-coatingprocess.[DOI:10.1143/APEX.1.021804]

PhotonicsResearchInstitute,NationalInstituteofAdvancedIndustrialScienceandTechnology,1-8-31Midorigaoka,Ikeda,Osaka563-8577,Japan1 DainichiseikaColorandChemicalsManufacturingCo.,Ltd.,1-9-4Horinouchi,Adachi-ku,

Tokyo123-8555,Japan* E-mailaddress:[email protected]


Highly Efficient Phosphorescent Organic Light-Emitting Diodes Using Alkyl-Substituted Iridium Complexes as a Solution-Processible Host MaterialToshimitsuTsuzuki*andShizuoTokito(ReceivedJanuary11,2008;acceptedJanuary24,2008;publishedonlineFebruary15,2008)

Wefabricatedhighlyefficientorganic light-emittingdiodes(OLEDs)

usingthesolutionprocessible iridiumcomplexeswhichhavelongalkyl

orcycloalkylsubstituentsinanancillaryligandasahostmaterialanda

redphosphorescentiridiumcomplexasanemittingguestbyspincoating

method.TheOLEDsemittedredphosphorescencefromtheguestand

theluminancereachedaround10,000cd/m2.TheefficiencyoftheOLED

improvedafterweaddedanelectrontransportmaterial (ETM)tothe

emittinglayer.TheOLEDusingamixtureofthealkylsubstitutediridium

complexandETMasthehostshowedanexternalquantumefficiencyof

10%.[DOI:10.1143/APEX.1.021805]

ScienceandTechnicalResearchLaboratories,NHK,Setagaya-ku,Tokyo157-8510,Japan* E-mailaddress:[email protected]


Waveguide-Integrated Si Nano-Photodiode with Surface-Plasmon Antenna and its Application to On-chip Optical Clock DistributionJunichiFujikata*,KoichiNose,JunUshida,KenichiNishi,MasaoKinoshita,TakanoriShimizu,ToshihideUeno,DaisukeOkamoto,AkikoGomyo,MasayukiMizuno,TaiTsuchizawa1,ToshifumiWatanabe1,KojiYamada1,SeiichiItabashi1,andKeishiOhashi(ReceivedNovember21,2007;acceptedDecember24,2007;publishedonlineJanuary25,2008)

Wedevelopedawaveguide-integratedSinano-photodiode(PD)with

asurfaceplasmon(SP)antennaforon-chipopticalclockdistribution.The

interfacialperiodicnano-scalemetal – semiconductor –metalSchottky

electrodeswereshowntofunctionasanSPopticalantennaandalsoas

anopticalcouplerbetweenaSiONwaveguideandaverythinSi-absorp-

tionlayer.Furthermore,averyhighspeedresponseof17psaswellas

enhancedphotoresponsivitywasachievedfora10-µmcouplinglength.

Byusingthis technology,wefabricatedaprototypeofa large-scale-

integration(LSI)on-chipopticalclocksystemanddemonstrated5GHzof

opticalclockcircuitoperationconnectedwitha4-branchingH-treestruc-

ture.[DOI:10.1143/APEX.1.022001]

MIRAI-Selete,34Miyukigaoka,Tsukuba,Ibaraki305-8501,Japan1 NTTMicrosystemIntegrationLabs.,3-1Morinosato-Wakamiya,Atsugi,Kanagawa



Semiconductor Waveguide Optical Isolator Incorporating Ferromagnetic Epitaxial MnSb for High Temperature OperationTomohiroAmemiya*,YusukeOgawa1,HiromasaShimizu2,HiroMunekata1,andYoshiakiNakano**


A1.5-µmnonreciprocal-losswaveguideoptical isolatorhaving

improved transverse-magnetic-mode (TM-mode) isolation ratiowas

developed.Thedeviceconsistedofan InGaAlAs/InP semiconductor

opticalamplifierwaveguidecoveredwithaferromagneticepitaxialMnSb

layer.BecauseofthehighCurietemperature(Tc=314°C)andstrong

magneto-optical effectofMnSb, thenonreciprocalpropagationof

11–12dB/mmhasbeenobtainedatleastupto70°C.

[DOI:10.1143/APEX.1.022002]

ResearchCenterforAdvancedScienceandTechnology,TheUniversityofTokyo,4-6-1Komaba,Meguro-ku,Tokyo153-8904,Japan1 ImagingScienceandEngineeringLaboratory,TokyoInstituteofTechnology,4259-G2-13

Nagatsuta,Midori-ku,Yokohama226-8502,Japan2 DepartmentofElectricalandElectronicEngineering,TokyoUniversityofAgricultureand

Technology,2-24-16Nakacho,Koganei,Tokyo184-8588,Japan* E-mailaddress:[email protected]**E-mailaddress:[email protected]




New Precise Fabrication Technology for Lenticular Lens Sheet with Black Stripe Patterns by Using Photo-Sensitive Material with Surface ModifierAtsushiNagasawa*,KatsuyaFujisawa1,andToshiyukiWatanabe2


Wehavedevelopedanewprecise fabrication technologyofa

lenticularlenssheetwithblackstripepatternsforarear-projectiontele-

vision.Theblackstripepatternshavetobeaccuratelyalignedtocylin-

dricallensesonthelenticularlenssheetandbeabletoabsorbambient

light.Ourproposedtechnologyutilizedaphoto-sensitivematerialwitha

surfacemodifierwhichcontrolssurfacefreeenergyforsurfacemodifica-

tion.Usingthismaterial,wecouldobtaintwopatternedareaswhichhad

differentsurfacefreeenergies.Furthermore,fabricationofblackstripe

patternsonthelenticularlenssheetwascarriedoutbyaself-alignment

method.This lenticular lenssheetwithblackstripepatternshadsimilar

opticalpropertiescomparedwithaconventionalone.

[DOI:10.1143/APEX.1.022003]

TechnologyResearchAssociationforAdvancedDisplayMaterials(TRADIM),2-24-16Nakamachi,Koganei,Tokyo184-0012,Japan1 KurarayCo.,Ltd.,41Miyukigaoka,Tsukuba,Ibaraki305-0841,Japan2 DepartmentofOrganicandPolymerMaterialsChemistry,TokyoUniversityofAgriculture

andTechnology,2-24-16Nakamachi,Koganei,Tokyo184-0012,Japan* E-mailaddress:[email protected]


Single-Mode Vertical-Cavity Surface-Emitting Lasers with a Deep-Etched Half-Ring-Shaped Holey StructureHung-PinD.Yang,Fang-ILai1,andJimY.Chi(ReceivedDecember10,2007;acceptedJanuary5,2008;publishedonlineJanuary25,2008)

Asingle-modeoxide-confinedvertical-cavitysurface-emitting laser

(VCSEL)withdeeply-etchedhalf-ring-shapedholeystructurefor fiber-

opticapplications isdemonstrated.Single fundamentalmodecontin-

uous-waveoutputpowerof2.6mWhasbeenachievedinthe850nm

range,witha thresholdcurrentofapproximately1mA.Side-mode

suppressionratio(SMSR)largerthan26dBhasbeenmeasured.Contrary

to thepreviously reported surface reliefmethods, thedeep-etched

(approximately2.2µmindepth)holeystructure inthispaperprovides

anotherapproachtoachievesingle-modeoperationoftheVCSELwitha

largeroxideaperture.[DOI:10.1143/APEX.1.022004]

ElectronicsandOptoelectronicsResearchLaboratories,IndustrialTechnologyResearchInstitute,Chutung31015,Hsinchu,Taiwan31015,R.O.C.1 DepartmentofElectricalEngineering,YuanZeUniversity,Chung-Li,Taiwan32003,R.O.C.


Generation of Periodic Sawtooth Optical Intensity by Phase-Shifting MaskShogoUra*,KenjiKintaka1,HideyukiAwazu,KenzoNishio,YasuhiroAwatsuji,andJunjiNishii2(ReceivedDecember19,2007;acceptedJanuary11,2008;publishedonlineFebruary1,2008)

Anewsimpleinterferenceexposuremethodusingaphase-shifting

maskwasdiscussedon thebasisofFourier synthesis for fabricating

blazedgratings.Phase-shiftingmaskwasdesignedwith244nmexpo-

sure-lightwavelengthtolaunchmultiplediffractionbeamssothatresul-

tant interferencepattern fit to requiredoptical intensityprofile.Fine

surface-reliefpatternonSiO2maskfor3-µm-periodsawtoothoptical-

intensityprofilewasfabricatedbyelectron-beamdirect-writing lithog-

raphywith30nmscanningstepandreliefheightof65nm.Sawtooth-

like intensityprofilewasdemonstratedwith theoreticallypredicted

interferencevisibility.[DOI:10.1143/APEX.1.022005]

DepartmentofElectronics,GraduateSchoolofScienceandTechnology,KyotoInstituteofTechnology,Kyoto606-8585,Japan1 PhotonicsResearchInstitute,NationalInstituteofAdvancedIndustrialScienceand

Technology,Tsukuba,Ibaraki305-8568,Japan2 PhotonicsResearchInstitute,NationalInstituteofAdvancedIndustrialScienceand

Technology,Ikeda,Osaka563-8577,Japan* E-mailaddress:[email protected]


Three-Dimensional Profiling of Refractive Index Distribution inside Transparent Materials by Use of Nonresonant Four-Wave Mixing MicroscopyKeisukeIsobe,TakehitoKawasumi,TakayukiTamaki,ShogoKataoka,YasuyukiOzeki,andKazuyoshiItoh(ReceivedDecember10,2007;acceptedJanuary15,2008;publishedonlineFebruary8,2008)

Wepropose that four-wavemixing (FWM)microscopy canbe

appliedtothree-dimensionalmappingofrefractive index(RI)structure

insidetransparentsamples.Wederiveananalyticalrelationshipbetween

theRIand the intensityof theFWMsignal that isdue tononreso-

nantopticalnonlinearity.Byusingtherelationship,theRIprofilecanbe

directlyandquantitativelyobtainedfromtheintensitydistributionofthe

FWMsignal.WeexperimentallydemonstratetheRIprofilingofaphase

gratingfabricatedinanon-alkaliglass.

[DOI:10.1143/APEX.1.022006]

DepartmentofMaterialandLifeScience,GraduateSchoolofEngineering,OsakaUniversity,2-1Yamadaoka,Suita,Osaka565-0871,Japan



Generation of High Efficiency �µm Laser Pulse from a Periodically Poled �mol% MgO-Doped LiNbO� Optical Parametric OscillatorRaviBhushan*,HidetsuguYoshida,KojiTsubakimoto,HisanoriFujita,MasahiroNakatsuka,NoriakiMiyanaga,YasukazuIzawa,HidekiIshizuki1,andTakunoriTaira1


Wereportonanopticalparametricoscillator(OPO)basedonalarge

apertureperiodicallypoled5mol%MgO-dopedLiNbO3 (PPMgLN).A

highaveragepowerQ-switchedNd:YAGlaseroperatingat1.064µm

producing10nspulsesatarepetitionrateof10Hzwasusedtopump

theOPO. Total outputpulse energyof126mJat2µmwith62 %

slopeefficiencywasachievedatrelatively lowpumppower intensity.

Temperaturetuningbehaviorofthequasi-phasematchedOPOwasalso

observed.[DOI:10.1143/APEX.1.022007]

InstituteofLaserEngineering,OsakaUniversity,2-6Yamada-oka,Suita,Osaka565-0871,Japan1 LaserResearchCenterforMolecularScience,InstituteforMolecularScience,38

Nishigonaka,Myodaiji,Okazaki,Aichi444-8585,Japan* E-mailaddress:[email protected]


Cylindrical Vector Laser Beam Generated by the Use of a Photonic Crystal MirrorYuichiKozawa,ShunichiSato,TakashiSato1,YoshihikoInoue1,YasuoOhtera2,andShojiroKawakami1,3


Aconcentricallypatternedphotoniccrystalmirrorwithpolariza-

tionselectivity fabricatedby theautocloningtechniquewasusedfor

thegenerationofradiallyandazimuthallypolarizedbeamsfromanNd:

YAGlasercavity.Byadoptingthephotoniccrystalmirrorastheoutput

couplerofthecavity,bothradiallyandazimuthallypolarizedbeamswere

obtainedwithsimilaroutputpoweras thatofanunpolarizedbeam

generatedbyaconventional,non-polarization-selectiveoutputcoupler.

[DOI:10.1143/APEX.1.022008]

InstituteofMultidisciplinaryResearchforAdvancedMaterials,TohokuUniversity,2-1-1Katahira,Aoba-ku,Sendai980-8577,Japan1 PhotonicLattice,Inc.,AobaIncubationSquare,AramakiazaAoba,Aoba-ku,Sendai

980-0845,Japan2 BiomedicalEngineeringResearchOrganization,TohokuUniversity,6-6-11Aramakiaza

Aoba,Aoba-ku,Sendai980-8579,Japan3 SendaiFoundationofAppliedInformationTechnology,AobaIncubationSquare,Aramaki

azaAoba,Aoba-ku,Sendai980-0845,Japan


Octave Spanning High Quality Super Continuum Generation Using �0nJ and �0�fs High Energy Ultrashort Soliton PulseNorihikoNishizawa*andMasaruHori1(ReceivedDecember21,2007;acceptedJanuary24,2008;publishedonlineFebruary15,2008)

Octavespanninghighqualitysupercontinuumisgenerated inall

fibresystem.A10nJand104fshighenergyultrashortsolitonpulse is

generatedfrom1psfiberchirpedpulseamplification laserusing large

modeareaphotoniccrystal fibre.Theconversionefficiency from1ps

pulse intoultrashortsolitonpulse is33%.A1.05–2.20µmoverone

octavespanninghighqualitysupercontinuumwith±5dBuniformity is

generatedusingthehighenergysolitonpulseandhighlynonlinearfiber.

[DOI:10.1143/APEX.1.022009]

DivisionofAdvancedScienceandBiotechnology,GraduateSchoolofEngineering,OsakaUniversity,2-1Yamadaoka,Suita,Osaka565-0871,Japan1 DepartmentofElectronicalEngineeringandComputerScience,GraduateSchoolof

Engineering,NagoyaUniversity,Furo-cho,Chikusa-ku,Nagoya464-8603,Japan* E-mailaddress:[email protected]


Nearly Temperature-Independent Saturation Drain Current in a Multi-Mesa-Channel AlGaN/GaN High Electron Mobility TransistorTakahiroTamura*,JunjiKotani,SeiyaKasai,andTamotsuHashizume**


Wefabricatedamulti-mesa-channel (MMC)structureby forming

aperiodictrench justunderagateelectrodetoimprovetheuniformity

ofeffectiveelectricfieldinthechannel inanAlGaN/GaNhighelectron

mobilitytransistor(HEMT).Auniqueperformance,i.e.,anearlytemper-

ature-independentsaturationdraincurrent,wasobservedintheMMC

device inawide temperature range.A two-dimensional (2D)poten-

tialcalculation indicatesthatthemesa-sidegateeffectivelymodulates

thepotential, resulting inafieldsurrounding2Delectrongas.Sucha

surrounding-fieldeffectandarelatively lowersourceaccessresistance

mayberelatedtoauniquecurrentbehaviorintheMMCHEMT.

[DOI:10.1143/APEX.1.023001]

ResearchCenterforIntegratedQuantumElectronicsandGraduateSchoolofInformationScienceandTechnology,HokkaidoUniversity,N13,W8,Kita-ku,Sapporo060-8628,Japan* E-mailaddress:[email protected]**E-mailaddress:[email protected]




Coulomb Blockade Oscillations in Narrow Corrugated Graphite RibbonsHisaoMiyazaki1,2,ShunsukeOdaka1,3,TakashiSato4,ShoTanaka4,HidenoriGoto2,4,AkinobuKanda2,4,KazuhitoTsukagoshi1,2,5,*,YouitiOotuka4,andYoshinobuAoyagi1,2,3


We reportCoulombblockadeoscillations inanatomically thin

graphiteribbonfabricatedbythemicromechanicalcleavagetechnique.

Aperiodiccurrentoscillationsasa functionof thegatevoltage indi-

catetheformationofmultipleCoulombislandsinsidethethingraphite

ribbon.WeconcludethattheCoulombislandsoriginatefrompuddles

ofelectronsandholescausedbytheinhomogeneousinterfacebetween

theribbonandthesubstrate.[DOI:10.1143/APEX.1.024001]

1 RIKEN,Wako,Saitama351-0198,Japan2 CREST,JapanScienceandTechnologyAgency,Kawaguchi,Saitama332-0012,Japan3 InterdisciplinaryGraduateSchoolofScienceandEngineering,TokyoInstituteofTechnology,

Midori-ku,Yokohama226-8502,Japan4 InstituteofPhysicsandTsukubaResearchCenterforInterdisciplinaryMaterialsScience,

UniversityofTsukuba,Tsukuba,Ibaraki305-8571,Japan5 NationalInstituteofAdvancedIndustrialScienceandTechnology,Umezono,Tsukuba,



Performance Estimation of Graphene Field-Effect Transistors Using Semiclassical Monte Carlo SimulationNaokiHarada*,MariOhfuti,andYujiAwano(ReceivedNovember16,2007;acceptedDecember28,2007;publishedonlineFebruary1,2008)

AsemiclassicalMonteCarlo simulationwas run toestimate the

performancesofamonolayerandabilayer (withverticalelectric field

of1V/nmapplied)graphene-channel field-effect transistor (FET).The

vertical fieldproducesabandgapof0.16eVandgivessemiconduc-

tivepropertiesinthebilayergraphene.Electronsinmonolayergraphene

showanotablevelocityovershootofupto7.6×107cm/s.Asub-0.1ps

transittimeisalsoexpectedina65-nmchanneldevice.Theperformance

ofabilayergraphene-channelFET is inferiortoamonolayergraphene

one,butcomparablewiththatofanInPhighelectronmobilitytransistor

(HEMT).Thislowerperformancemaybeattributedtotheelectroneffec-

tivemassproducedbytheverticalfield.[DOI:10.1143/APEX.1.024002]

NanotechnologyResearchCenter,FujitsuLaboratoriesLtd.,Atsugi,Kanagawa243-0197,Japan* E-mailaddress:[email protected]


Electrostatic Imprint Process for GlassHidekiTakagi,Shin-ichiMiyazawa,MasaharuTakahashi,andRyutaroMaeda(ReceivedNovember27,2007;acceptedJanuary5,2008;publishedonlineFebruary1,2008)

Inusual thermal imprintprocess,moldpatternsaretransferredby

applyingmechanicalpressuresatelevatedtemperatures.Wehavedevel-

opedanewimprintprocessforglass,whichutilizeselectrostaticforceas

adrivingforcefordeformation.Inthemethod,highdcvoltageisapplied

betweenamoldandaglassspecimensothat themoldbecomesan

anode.Thismethodenablesglassformingat lowertemperatureswith

smallermechanicalforcecomparedtousualthermalimprintprocess. In

addition,thismethodissuitableforsmallpatterns lessthan1µm.It is

expectedthatthismethodrealizes large-areaandhigh-efficiencynano-

formingprocessforglass.[DOI:10.1143/APEX.1.024003]

AdvancedManufacturingResearchInstitute,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),Tsukuba,Ibaraki305-8564,Japan


Nitrogen–Oxygen Complexes Associated with Shallow Thermal Donors in SiliconHaruhikoOno(ReceivedDecember10,2007;acceptedJanuary27,2008;publishedonlineFebruary15,2008)

A structuralmodel isdescribed for the shallow thermaldonors

(STDs),whichtypicallyconsistofsevenidenticalabsorptionpeaksthat

arecausedbyelectronictransition.IntheSTDfamily,attentionwaspaid

to the247cm-1peak thatappears tostronglydependonthecondi-

tionofboththecrystalgrowthandtheannealing.WeexaminedNO

configurationandthesixkindsofNO+Oiconfiguration.Semi-empirical

molecularorbitalcalculationsfor thesecomplexessuggestedthatnot

onlythecomplexwiththeC2vsymmetrybutalsotheasymmetricNO+Oi

complexescouldsimultaneouslyexistintheSicrystal.Weconcludedthat

the247cm-1peak,whichwashighlyunstableandbehavedoddlyduring

annealing,mightbetheNOcomplexandthattheothersixSTDpeaks

mightcorrespondtothesixkindsofNO+Oicomplexes.

[DOI:10.1143/APEX.1.025001]

KanagawaIndustrialTechnologyCenter,Ebina,Kanagawa243-0435,Japan



Point Spread Function for the Calculation of Acid Distribution in Chemically Amplified Resists for Extreme Ultraviolet LithographyTakahiroKozawa1,2,*,AkinoriSaeki1,2,andSeiichiTagawa1,2,**


Theprocess simulator isakey technology inextremeultraviolet

(EUV)lithography,whichisregardedastheultimateinprojectionlithog-

raphy. The requirement for theaccuracyofprocess simulatorshas

becomeincreasinglystrictwiththeshrinkageoffeaturesize. Inchemi-

callyamplifiedEUVresists,acidgeneratorsdecomposethroughareac-

tionwiththermalizedelectrons(~25meV).Thissensitizationmechanism

ofEUVresists isanalogoustothat inducedbyanelectronbeam(EB).

However,theaciddistributioninEUVresistsisdifferentfromthatinEB

resistsbecauseofthemultispureffect,whichiscausedbythecharged

intermediatesnarrowlydistributedaroundtheabsorptionpointsofEUV

photons. Inthiswork,theauthorsformulateaproposedpointspread

functionfortheEUVlithographyprocessbasedonchemicallyamplified

resists.[DOI:10.1143/APEX.1.027001]

1 TheInstituteofScientificandIndustrialResearch,OsakaUniversity,8-1Mihogaoka,Ibaraki,Osaka567-0047,Japan

2 CREST,JapanScienceandTechnologyAgency,c/oOsakaUniversity,8-1Mihogaoka,Ibaraki,Osaka567-0047,Japan

* E-mailaddress:[email protected]**E-mailaddress:[email protected]


Hyper Rheology Measurement by Emission and Collision of Micro-Fluid ParticlesHideakiKutsunaandKeijiSakai(ReceivedDecember11,2007;acceptedJanuary11,2008;publishedonlineFebruary8,2008)

We introduceasystemtomeasure themechanicalpropertiesof

fluidsunderhighsheardeformationratesofupto106s -1.Thenewly

developedmicro-fluidemissionnozzleremarkablyextendedthevariety

ofliquidsto,forexample,organicsolvents,strongalkalisandacids,and

viscousfluids.Thedynamicbehaviorofafluidafterthehead-oncollision

ofthetwoemittedparticleswasobservedbythestroboscopicmethod.

Thesurfacetensionandviscosityweredeterminedfromtheresonant

frequencyanddecayconstantoftheresonantoscillationbycomparison

withnumericalsimulation.Anapproximatetheorytodescribethelarge-

amplitudeoscillationisalsopresented.[DOI:10.1143/APEX.1.027002]

InstituteofIndustrialScience,UniversityofTokyo,4-6-1Komaba,Meguro-ku,Tokyo153-8505,Japan


Extremely Small Proximity Effect in �0keV Electron Beam Drawing with Thin Calixarene Resist for �0×�0nm� Pitch Dot ArraysSumioHosaka1,3,*,ZulfakriMohamad2,MasumiShira2,HirotakaSano2,YouYin1,AkihiraMiyachi3,andHayatoSone1


Westudiedproximityeffect in30keVelectronbeam(EB)drawing

withcalixareneresistforpatternedmediaandquantumdevices.Using

about15-nm-thickcalixareneresistonSisubstrate inconventionalEB

drawingsystem,theproximityeffecthasbeenstudiedbyformingand

observing20-,25-,30-,and40-nm-pitchresistdotarraysandmeasuring

exposuredosage intensitydistribution (EID) function.Asaresult, the

proximityeffect isnegligiblesmalldue tocomparingwithsomedot

sizesincenter,sideandcornerof2µmsquarewith25×25nm2pitchdot

arrays. Inaddition,theproximityeffectparameterη inEIDfunction is

lessthan0.3.ItisclearthattheEBdrawingandcalixareneresistsystem

isverysuitable for formingultrahighpackeddotarrayspattern.We

demonstrated20×20nm2pitchresistdotarrays(about1.6Tb / in.2)with

adotdiameterofabout14nmandthesamesizeaseverywhereinthe

pattern.[DOI:10.1143/APEX.1.027003]

1 DepartmentofProductionScienceTechnology,GraduateSchoolofEngineering,GunmaUniversity,1-5-1Tenjin,Kiryu,Gunma376-8515,Japan

2 DepartmentofNanoMaterialSystems,GraduateSchoolofEngineering,GunmaUniversity,1-5-1Tenjin,Kiryu,Gunma376-8515,Japan

3 AdvancedTechnologyResearchCenter(ATEC),GunmaUniversity,1-5-1Tenjin,Kiryu,Gunma376-8515,Japan



Dependence of Acid Generation Efficiency on Molecular Structures of Acid Generators upon Exposure to Extreme Ultraviolet RadiationRyoHirose,TakahiroKozawa*,SeiichiTagawa**,ToshiyukiKai1,andTsutomuShimokawa1


Thetrade-offbetweenresolution,sensitivity,andlineedgerough-

ness(LER)isthemostseriousproblemforthedevelopmentofsub-30nm

resistsbasedonchemicalamplification.Becauseof this trade-off, the

increase inacidgenerationefficiency isessentially required forhigh-

resolutionpatterningwithhighsensitivityand lowLER. In thisstudy,

weinvestigatedthedependencesofacidgenerationefficiencyonthe

molecularstructureandconcentrationofacidgeneratorsuponexpo-

suretoextremeultraviolet(EUV)radiation.Theacidgenerationefficiency

(thenumberofacidmoleculesgeneratedbyasingleEUVphoton)was

obtainedwithintheacidgeneratorconcentrationrangeof0–30wt%

forfivetypesofionicandnonionicacidgenerators.

[DOI:10.1143/APEX.1.027004]

TheInstituteofScientificandIndustrialResearch,OsakaUniversity,8-1Mihogaoka,Ibaraki,Osaka567-0047,Japan1 JSRCorp.,100Kawajiri-cho,Yokkaichi,Mie510-8552,Japan* E-mailaddress:[email protected]**E-mailaddress:[email protected]




Longitudinal and Transverse Coupling of the Beam Temperature Caused by the Laser Cooling of ��Mg+

MikioTanabe*,TakehiroIshikawa,MasaoNakao,HikaruSouda,MasahiroIkegami1,ToshiyukiShirai1,HiromuTongu1,andAkiraNoda1

(ReceivedNovember27,2007;acceptedDecember18,2007;publishedonlineFebruary1,2008)

Alaser-coolingexperimentofa40keV24Mg+beamwascarriedout

inthesmall laser-equippedstoragering(S-LSR).Alaserco-propagating

withthebeamandaninductionacceleratorwereutilizedintheexperi-

ment.The lowest longitudinal temperatureachieved in thepresent

experimentwas3.6Kfor3×104 ionsstored inthering. Itwasfound

thatthenumberofstoredionsisrelatedtothetemperatureatthefinal

equilibriumstateofthelasercooling.Thisrelationshowsthatthelongi-

tudinaltemperatureofthelaser-cooledbeamlinearlycoupleswiththe

transverseonethroughintra-beamscattering.

[DOI:10.1143/APEX.1.028001]

DepartmentofPhysics,GraduateSchoolofScience,KyotoUniversity,Kyoto606-8502,Japan1 AdvancedResearchCenterforBeamScience,InstituteforChemicalResearch,Kyoto

University,Gokasho,Uji,Kyoto611-0011,Japan* E-mailaddress:[email protected]


Synthesis and Thermoelectric Properties of Silicon Clathrates Sr�AlxGa��-xSi�0 with the Type-I and Type-VIII StructuresKengoKishimoto*,NaoyaIkeda,KojiAkai1,andTsuyoshiKoyanagi(ReceivedJanuary14,2008;acceptedFebruary21,2008;publishedonlineMarch14,2008)

Nominal composition Sr8AlxGa16-xSi30 (0≤x≤16) samples were

preparedbypowdermetallurgy.Thesampleswithx=0–7exhibitedthe

type-Iclathratestructure (Pm3–n,No.223),while thesampleswithx=

8–13almostexhibitedthetype-VIIIclathratestructure(I4–3m,No.217).

ThesesamplespossessedtheelectricalconductivitiesandSeebeckcoef-

ficients typicalofn-typedegeneratedsemiconductors.Theresultson

theirthermoelectricpropertiesindicatethatthetype-VIIISrAlGaSiclath-

ratewouldbeamoreefficientthermoelectricmaterial thanthetype-I

SrAlGaSi clathrate. Forexample, the type-VIII Sr8Al9Ga7Si30 sample

hadamaximumpowerfactorof11µWcm-1K-2at1000Kandaroom

temperatureHallmobilityof24cm2V-1 s-1,while thoseof the type-I

Sr8Al6Ga10Si30samplewere7µWcm-1K-2and5cm2V-1s-1,respectively.

[DOI:10.1143/APEX.1.031201]

GraduateSchoolofScienceandEngineering,YamaguchiUniversity,Ube,Yamaguchi755-8611,Japan1 MediaandInformationTechnologyCenter,YamaguchiUniversity,Ube,Yamaguchi



Ferroelectric Polarization Reversal by a Magnetic Field in Multiferroic Y-type Hexaferrite Ba�Mg�Fe��O��KoujiTaniguchi,NobuyukiAbe1,ShintaroOhtani1,HiroshiUmetsu1,andTaka-hisaArima(ReceivedJanuary20,2008;acceptedFebruary6,2008;publishedonlineFebruary29,2008)

Coexistenceof the ferroelectricpolarizationand spontaneous

magnetizationhasbeen found inY-typehexaferriteBa2Mg2Fe12O22.

Thereversalofmagnetizationbyasmallmagneticfieldbelow~0.02T

accompaniesanelectricpolarizationreversal throughtheclampingof

ferrimagneticandferroelectricdomainwalls.Thisbehaviorcanbepoten-

tiallyusedasamagneticallyrewritableferroelectricmemoryandanelec-

tricallyrewritablemagneticmemory.[DOI:10.1143/APEX.1.031301]

InstituteofMultidisciplinaryResearchforAdvancedMaterials,TohokuUniversity,Sendai980-8577,Japan1 DepartmentofPhysics,GraduateSchoolofScience,TohokuUniversity,Sendai980-8577,

Japan


Determination of Penetration Depth of Transverse Spin Current in Ferromagnetic Metals by Spin PumpingTomohiroTaniguchi1,2,SatoshiYakata3,HiroshiImamura2,andYasuoAndo3

(ReceivedFebruary7,2008;acceptedFebruary21,2008;publishedonlineMarch14,2008)

Spinpumping innonmagnetic / ferromagneticmetalmultilayers is

studiedboth theoreticallyandexperimentally.Weshowthat the line

widthsoftheferromagneticresonance(FMR)spectrumdependonthe

thicknessoftheferromagneticmetallayers,whichmustnotbeinreso-

nancewiththeoscillatingmagneticfield.Wealsoshowthatthepene-

trationdepthsofthetransversespincurrentinferromagneticmetalscan

bedeterminedbyanalyzingthe linewidthsof theirFMRspectra.The

obtainedpenetrationdepths inNiFe,CoFe,andCoFeBwere3.7,2.5,

and12.0nm,respectively.[DOI:10.1143/APEX.1.031302]

1 InstituteforMaterialsResearch,TohokuUniversity,Sendai980-8577,Japan2 NanotechnologyResearchInstitute(NRI),NationalInstituteofAdvancedIndustrialScience

andTechnology(AIST),1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan3 DepartmentofAppliedPhysics,GraduateSchoolofEngineering,TohokuUniversity,Sendai

980-8579,Japan



Microcrystalline Si�-xGex Solar Cells Exhibiting Enhanced Infrared Response with Reduced Absorber ThicknessTakuyaMatsui1,*,Chia-WenChang1,TomoyukiTakada1,2,MasaoIsomura2,HiroyukiFujiwara1,andMichioKondo1

(ReceivedJanuary25,2008;acceptedFebruary14,2008;publishedonlineMarch7,2008)

Thin filmp – i –n junctionsolarcells incorporatinghydrogenated

microcrystallineSi1-xGex(µc-Si1-xGex:H)absorberilayers(1µm)havebeen

fabricatedbyplasma-enhancedchemicalvapordepositioninthecompo-

sitionrangeof0≤x≤0.35.ByincreasingGecontentfromx=0to0.15–0.2,

short-circuitcurrentdensityincreasesby~5mA/cm2withspectralsensi-

tivitiesextending into the infraredwavelengths (>600nm).However,

solarcellparametersfor largerGecontents(x>0.2)areloweredbythe

increasedchargecarrierrecombinationintheµc-Si1-xGex:H i layer.Asa

result,a6.3%efficientsolarcellisobtainedatx=0.2,exhibitinginfrared

responseevenhigherthanthatofdouble-thicknessµc-Si:Hsolarcells.

Thesolarcell showsexcellentperformancestabilityunderprolonged

lightsoaking.[DOI:10.1143/APEX.1.031501]

1 ResearchCenterforPhotovoltaics,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan

2 DepartmentofElectricalandElectronicEngineering,TokaiUniversity,1117Kitakaname,Hiratsuka,Kanagawa259-1292,Japan



Rare-Earth-Dependent Magnetic Anisotropy in REBa�Cu�OyAtsushiIshihara,ShigeruHorii*,TetsuoUchikoshi1,TohruS.Suzuki1,YoshioSakka2,HirakuOgino,Jun-ichiShimoyama,andKohjiKishio(ReceivedJanuary24,2008;acceptedFebruary17,2008;publishedonlineMarch7,2008)

Wereportmagneticanisotropies(Δχ)dependingonrareearth(RE)

element intheparamagneticREBa2Cu3Oy (RE123)systemasanimpor-

tantfindingofmagneto-scientificgrain-orientation.Thec-axis-oriented

RE123powdersamplesusingstaticor rotatingmagnetic fieldswere

fabricatedatroomtemperaturetoclarifyΔχ.Theireasyaxesofmagneti-

zationweremainlydominatedbysecond-orderStevensfactors,whereas

|Δχ| largelydependedonyandREelements.Especially forheavyRE

elements, |Δχ| reachedtheorderof10-4, indicating thatappropriate

choiceofREdirectly leadstoadrasticreductionofrequiredmagnetic

fieldsforgrain-orientationofRE123.[DOI:10.1143/APEX.1.031701]

DepartmentofAppliedChemistry,UniversityofTokyo,Tokyo113-8656,Japan1 NanoCeramicsCenter,NationalInstituteforMaterialsandScience,Tsukuba,Ibaraki

305-0047,Japan2 WPICenterforMaterialsNanoarchitectonics,NationalInstituteforMaterialsandScience,

Tsukuba,Ibaraki305-0047,Japan* E-mailaddress:[email protected]


Time Resolution Improvement of Superconducting NbN Stripline Detectors for Time-of-Flight Mass SpectrometryKojiSuzuki*,ShigehitoMiki1,ShigetomoShiki,ZhenWang1,andMasatakaOhkubo(ReceivedJanuary25,2008;acceptedFebruary14,2008;publishedonlineMarch7,2008)

Wehaveappliedsuperconductingstriplinedetectors (SSLDs) for

time-of-flightmassspectrometry (TOF-MS)asmoleculedetectors.Two

SSLDs,whichconsistof7-nm-thickniobiumnitride(NbN)striplineswith

differentlinewidthsof200or300nmonaMgOsubstrate,werefabri-

catedto investigate theeffectsofkinetic inductanceontimeresolu-

tion.Wehaveobservedultrafast iondetectionsignalswithrisetimes

of360–640ps,andsuccessfullyobtainedmassspectraforapeptide,

AngiotensinI,andaprotein,bovineserumalbumin(BSA)atanenergy

of17.5keV.Ithasbeenconfirmedthattheresponsetimeisgovernedby

thekineticinductanceofthenano-striplines.

[DOI:10.1143/APEX.1.031702]

ResearchInstituteofInstrumentationFrontier,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan1 NationalInstituteofInformationandCommunicationsTechnology,Kobe651-2492,Japan* E-mailaddress:[email protected]


Effect of c-Axis-Correlated Disorders on the Vortex Diagram of the Pinning StateMasafumiNamba,SatoshiAwaji,KazuoWatanabe,TsutomuNojima1,SatoruOkayasu2,MasashiMiura3,YusukeIchino3,YutakaYoshida3,YoshiakiTakai3,TomoyaHoride4,PaoloMele4,5,andKanameMatsumoto5


Theintroductionofthec-axis-correlateddisorderisapromisingtech-

niqueforthe improvementofthecriticalcurrentdensityJc forB//cof

REBa2Cu3Oy (RE123)filmsandtapes. Inordertounderstandthevortex

pinningmechanismwith thedifferentvarietyof thec-axis-correlated

disorder, theangulardependenceofJcwasmeasured indetail foran

Y123filmwithBaZrO3nano-rods,aSm123filmwithfinenano-particles

andedgedislocationsandanY123filmwithcolumnardefects intro-

ducedbytheheavy-ionirradiationparalleltothec-axis.Wefoundthat

thevortexpinningstateforthevarietyofthec-axis-correlatedpinning

issimilar in lowfieldsbelowthematchingfield,but itshowsdifferent

behaviorsinhighfieldsabovethematchingfield.Itisconsideredthatthe

interstitialvorticesinteractedwiththec-axis-correlateddisordersthrough

thevortexinteractionmayplayanimportantrolefortheappearanceof

thec-axis-correlatedpinningbehavior inahigh-fieldregionabovethe

matchingfield.[DOI:10.1143/APEX.1.031703]

HighFieldLaboratoryforSuperconductingMaterials,InstituteforMaterialsResearch,TohokuUniversity,Sendai980-8577,Japan1 InstituteforMaterialsResearch,TohokuUniversity,Sendai980-8577,Japan2 JapanAtomicEnergyAgency,Tokai-mura,Naka-gun,Ibaraki319-1195,Japan3 NagoyaUniversity,Nagoya464-8603,Japan4 KyotoUniversity,Kyoto606-8501,Japan5 KyushuInstituteofTechnology,Kitakyushu804-8550,Japan




Reduction of Viewing-Angle Dependent Color Shift in a Reflective Type Cholesteric Liquid Crystal Color FilterWon-GunJang*,TaeWonBeom1,HaoCui1,JongRakPark1,SeongJinHwang2,YoungJinLim2,andSeungHeeLee2


Thereflectivetypecolorfilter for the liquidcrystaldisplays (LCDs)

wasproducedusingcholesteric liquidcrystalmonomerswhosephase

ischaracterizedbytheuniqueoptical featuresofselective reflection.

Periodicmicrometerscalehemi-sphericalphotoresist (PR)patternswere

formedonglasssubstratesbythermalreflowmethodafterphotolithog-

raphy.Cholestericcolorfilterfilmsforred,green,andbluelightreflec-

tionswerethenproducedandtheviewingangledependencewasinves-

tigatedandcomparedwiththatofreflectedlightonthenon-patterned

substrates.Computersimulationsusing“LightTools”werealsocarried

out,and itwasconfirmedthatthecolorshiftsweremuchsmalleron

thepatternedsubstratesbybareeyesandCommission Internationale

de'Eclairage(CIE)chromaticitycoordinationanalysisqualitatively.

[DOI:10.1143/APEX.1.032001]

KoreaPhotonicsTechnologyInstitute,Wolchul-dong,Buk-gu,Gwangju500-460,Korea1 DepartmentofPhotonicEngineering,ChosunUniversity,375Seosok-dong,Dong-gu,

Gwangju501-759,Korea2 BK-21PolymerBINFusionResearchTeam,ResearchCenterofIndustrialTechnology,School

ofAdvancedMaterialsEngineering,ChonbukNationalUniversity,Chonju,Chonbuk561-756,Korea



Lowering Threshold by Energy Transfer between Two Dyes in Cholesteric Liquid Crystal Distributed Feedback LasersKojiSonoyama,YoichiTakanishi*,KenIshikawa,andHideoTakezoe(ReceivedDecember7,2007;acceptedFebruary8,2008;publishedonlineFebruary29,2008)

LoweringlasingthresholdbasedontheFörster-typeenergytransfer

processhasbeenstudiedindistributedfeedback(DFB)lasersofcholes-

tericliquidcrystals(CLCs)containingtwodyes.Wefoundthatthelasing

thresholdintheenergytransferprocesswasloweredtolessthanhalfof

thatindirectexcitationprocesses.Thiseffectisattributedtothesuppres-

sionofself-absorptionofadye(acceptor).Thisprovidesamethodfor

loweringthreshold inCLC-DFBlaserscontainingmultipledyesparticu-

larlywithasmallStokesshift.[DOI:10.1143/APEX.1.032002]

DepartmentofOrganicandPolymericMaterials,TokyoInstituteofTechnology,2-12-1-S8-42O-okayama,Meguro-ku,Tokyo152-8552,Japan* Presentaddress:DepartmentofPhysics,KyotoUniversity,Kitashirakawa-oiwake-cho,Sakyo-

ku,Kyoto606-8502,Japan.


Second Harmonic Generation with High Conversion Efficiency and Wide Temperature Tolerance by Multi-Pass SchemeTetsuroMizushima*,HiroyukiFuruya,ShinichiShikii,KoichiKusukame,KiminoriMizuuchi,andKazuhisaYamamoto(ReceivedJanuary21,2008;acceptedFebruary17,2008;publishedonlineMarch7,2008)

Weproposedamulti-passsecondharmonicgenerationschemein

whichcondensedfundamental lightpassedthroughanonlinearcrystal

manytimes.Themulti-passschemewasrealizedbyusingawideperi-

odically-poledMgO:LiNbO3,concavemirrorsandcondensingoptics.The

totalwavelengthconversionefficiencyof themulti-passschemewas

increasedbecausenon-convertedfundamental lightwhichhadpassed

throughthenonlinearcrystalwasre-injectedandcondensed intothe

nonlinearcrystalandconverted.Moreoverthetotal temperaturetoler-

anceofthemultipasseswaswidenedbecausethefundamentalbeam

passeshaddifferentphase-matchingtemperatureandcompensatedfor

missconversionsofotherpasses. In thiswork,continuous-wave5W

greenlight(532nm)with66%conversionefficiencyandwidetempera-

turetolerancewereobtained.[DOI:10.1143/APEX.1.032003]

AVCoreTechnologyDevelopmentCenter,MatsushitaElectricIndustrialCo.,Ltd.,3-1-1Yagumo-naka-machi,Moriguchi,Osaka570-8501,Japan* E-mailaddress:[email protected]


Green Photoluminescence from GaInN Photonic CrystalsHitoshiKitagawa1,2,*,ToshihideSuto1,2,MasayukiFujita1,**,YoshinoriTanaka1,TakashiAsano1,andSusumuNoda1,3,***

(ReceivedDecember21,2007;acceptedFebruary21,2008;publishedonlineMarch14,2008)

Wehave investigatedgreen-emittingGaInN two-dimensional

photoniccrystalswithairholesthatpenetratethroughtheactivelayer.

Atroomtemperature,theobservedphotoluminescence intensityfrom

thephotoniccrystal isapproximatelythreetimesthatofasamplewith

nophotoniccrystalstructure.Thisisduetothelowsurfacerecombina-

tionvelocity(1.4×103cm/s)ofGaInNattheairholeedgesandahigher

degreeoflightextractionbythediffractioneffect.

[DOI:10.1143/APEX.1.032004]

1 DepartmentofElectronicScienceandEngineering,KyotoUniversity,Kyotodaigaku-katsura,Nishikyo-ku,Kyoto615-8510,Japan

2 ProcessTechnologyDVLPMT.CenterALPSElectricCo.,Ltd.,Sendai981-3208,Japan3 PhotonicsandElectronicsScienceandEngineeringCenter,KyotoUniversity,Kyotodaigaku-

katsura,Nishikyo-ku,Kyoto615-8510,Japan* E-mailaddress:[email protected]**E-mailaddress:[email protected]***E-mailaddress:[email protected]



Position-Controlled Si Nanocrystals in a SiO� Thin Film Using a Novel Amorphous Si Ultra-Thin-Film “Nanomask” due to a Bio-Nanoprocess for Low-Energy Ion ImplantationYujiNakama*,ShinjiNagamachi1,JunOhta,andMasahiroNunoshita(ReceivedJanuary22,2008;acceptedFebruary4,2008;publishedonlineFebruary22,2008)

Anano-sizeandpositioncontrollingtechniqueofsilicon-nanocrystal

(Si-NC)assemblies inaSiO2 thin filmhasbeen investigatedbyusing

low-energyionimplantation(0.6keV)throughanovelamorphoussilicon

(a-Si)ultra-thin-film“nanomask”.Thisa-Sinanomaskwasdevelopedon

thebasisofaself-assembledbio-nanoprocesswithproteins“ferritin”.Si

NCsweresynthesizedfromtheexcessSi+ionsimplantedinaSiO2matrix

byannealingwithaNd:YAGpulsed laser.Asaresult,almostordered

Si-NCassemblieswithverysmallanduniformsize(3.0±0.3nm)andinter-

particleseparation(5to6nm)wereobtainedbythetranscriptionofthe

a-Sinanomaskpattern.[DOI:10.1143/APEX.1.034001]

GraduateSchoolofMaterialsScience,NaraInstituteofScienceandTechnology,8916-5Takayama,Ikoma,Nara630-0101,Japan1 IonEngineeringResearchInstituteCorporation,2-8-1Tudayamate,Hirakata,Osaka



Carbon Nanotubes from a Divided Catalyst: the Carbon Transmission MethodTakeshiHikata,KazuhikoHayashi,TomoyukiMizukoshi1,YoshiakiSakurai1,ItsuoIshigami1,TakaakiAoki2,ToshioSeki2,andJiroMatsuo2

(ReceivedJanuary23,2008;acceptedFebruary4,2008;publishedonlineFebruary22,2008)

Wehave fabricatedcarbonnanotubes (CNTs)usingacatalyzed

growthtechniquethatwecall thecarbontransmissionmethod(CTM).

Wecouldcontrolindependentlyfunctionsforcarbonsourcegassupply

andCNTgrowthbyusingafoilbarrier(Ag)penetratedbypureFefibers.

CNTsgrewononeendoftheFefibers, formedfromdiffusedcarbon

thatoriginatesincarbonsourcegasattheotherendofthefibers.Long

CNTswithlengthover100µmwereobtainedontheendoftheFefibers

inthecarbontransmittedside.[DOI:10.1143/APEX.1.034002]

SumitomoElectricIndustries,Ltd.,Osaka554-0024,Japan1 TechnologyResearchInstituteofOsakaPrefecture,Osaka594-1157,Japan2 FacultyofEngineeringQuantumScienceandEngineeringCenter,KyotoUniversity,Kyoto

606-8501,Japan


Optical and Conductive Characteristics of Metallic Single-Wall Carbon Nanotubes with Three Basic Colors; Cyan, Magenta, and YellowKazuhiroYanagi*,YasumitsuMiyata,andHiromichiKataura(ReceivedFebruary1,2008;acceptedFebruary8,2008;publishedonlineFebruary29,2008)

Wepresentprotocols topreparehigh-puritymetallic single-wall

carbonnanotubes(SWCNTs)withthreebasiccolors,cyan,magenta,and

yellow,throughdensitygradientcentrifugations.Additionofdeoxycho-

latesodiumsaltsasaco-surfactantcouldimproveseparationcapability

formetallicSWCNTsincentrifugations.Weappliedtheimprovedsepara-

tionprotocolstotheSWCNTswithdifferentaveragediameters(1.34,1.0,

and0.84nm),andobtainedthemetallicSWCNTswithcyan,magenta,

andyellowcolors.Theiroptical / conductivecharacteristicswererevealed,

andconductivecolorfilmswereformedfromthemetallicSWCNTs.

[DOI:10.1143/APEX.1.034003]

JST/CREST,NanotechnologyResearchInstitute,NationalInstituteofAdvancedIndustrialScienceandTechnologies(AIST),Tsukuba,Ibaraki305-8562,Japan* E-mailaddress:[email protected]


High-Quality Carbon Nanotube Growth at Low Temperature by Pulse-Excited Remote Plasma Chemical Vapor DepositionYuichiYamazaki,NaoshiSakuma,MasayukiKatagiri,MarikoSuzuki,TadashiSakai,ShintaroSato1,MizuhisaNihei1,andYujiAwano1


Carbonnanotube(CNT)growthattemperaturesbelow400°Cby

pulse-excitedremoteplasmachemicalvapordepositionwasdemon-

strated.Reductionofplasmapowerwascarriedoutinordertodecrease

theamountofallparticles, ions,electrons,andradicals. Inaddition,

abiasedplate-typescreeningelectrodewas introducedtoremovalof

chargedparticles, ions,andelectrons.Thenegativebiasbelow50V

wasmosteffectiveforgrowthrate.High-qualityCNTgrowthwiththe

growth rateof98nm/minwas successfullyobtainedat400°C.The

resultssuggestthatbothremovalofchargedparticlesandcontrolofthe

amountofradicalsareimportantforhigh-qualityCNTgrowthattemper-

aturesbelow400°C.[DOI:10.1143/APEX.1.034004]

MIRAI–Selete,1Komukai-Toshiba-cho,Saiwai-ku,Kawasaki212-8582,Japan1 MIRAI–Selete,10-1Morinosato-Wakamiya,Atsugi,Kanagawa243-0197,Japan




Real-Time Observation of Growth of Tungsten Oxide Nanowires with a Scanning Electron MicroscopeKeigoKasuya*,TakeshiOoi**,YusukeKojima,andMasayukiNakao(ReceivedJanuary30,2008;acceptedFebruary14,2008;publishedonlineMarch7,2008)

Weobservedthegrowthprocessof tungstenoxidenanowires in

real-timewithafieldemissionscanningelectronmicroscope(SEM).The

observationwasperformedbyanewin-situobservationsystemdesigned

toperformtwofunctions:heatingoftungstenfilmandlocalsupplyof

O2gas.Thenanowiresgrewafterthenucleationonthesurface.Their

lengthextendedwithtimekeepingthedirectionconstant.Thegrowth

ratedecreasedwithexponential.[DOI:10.1143/APEX.1.034005]

DepartmentofEngineeringSynthesis,TheUniversityofTokyo,7-3-1Hongo,Bunkyo-ku,Tokyo113-8656,Japan* Presentaddress:CentralResearchLaboratory,HitachiLtd.,1-280Higashi-koigakubo,

Kokubunji,Tokyo185-8601,Japan.E-mailaddress:[email protected]**Presentaddress:KomatsuLtd.,1200Manda,Hiratsuka,Kanagawa254-8567,Japan


Adsorption Properties of a Gold-Binding Peptide Assessed by its Attachment to a Recombinant Apoferritin MoleculeKazutakaIshikawa1,KiyohitoYamada1,2,ShinyaKumagai2,Ken-IchiSano3,4,KiyotakaShiba3,4,IchiroYamashita1,2,4,andMimeKobayashi1,4,*


Theadsorptionpropertiesofarecombinantapoferritinproteinfused

toagold-bindingpeptidewerecharacterized.The resultsofquartz

crystalmicrobalancemeasurementsshowedthatthefusionproteinpref-

erentiallyadsorbstogoldsurfaces.Scanningelectronmicroscopyalso

revealedthattheproteinselectivelyadsorbedontoananometer-scale

goldpatternonaSiO2surfacefabricatedbyelectron-beamlithography.

Ourresults indicatethatnanodotsandnanowiressynthesizedusinga

biotemplatecanbeselectivelyplacedontoagoldsurfacebygenetically

modifyingtheoutersurfaceofthebiotemplate.This techniquerepre-

sentsan importantsteptowardbiotemplate-mediatedfabricationofa

nanometer-scaleddevicethatutilizesgoldelectrodes.

[DOI:10.1143/APEX.1.034006]

1 GraduateSchoolofMaterialsScience,NaraInstituteofScienceandTechnology,Ikoma,Nara630-0192,Japan

2 AdvancedTechnologyResearchLaboratories,MatsushitaElectricIndustrialCo.,Ltd.,Hikaridai,Seika,Kyoto619-0237,Japan

3 DepartmentofProteinEngineering,CancerInstitute,JapaneseFoundationforCancerResearch,Koto-ku,Tokyo135-8550,Japan

4 CoreResearchforEvolutionalScienceandTechnology,JapanScienceandTechnologyAgency,Kawaguchi,Saitama332-0012,Japan



Inter-Layer Screening Length to Electric Field in Thin Graphite FilmHisaoMiyazaki1,2,ShunsukeOdaka1,3,TakashiSato4,ShoTanaka4,HidenoriGoto2,4,AkinobuKanda2,4,KazuhitoTsukagoshi1,2,5,*,YouitiOotuka4,andYoshinobuAoyagi1,2,3


Electricconductioninthingraphitefilmwastunedbytwogateelec-

trodestoclarifyhowthegateelectricfieldinduceselectriccarriersinthin

graphite.Thegraphitewassandwichedbetweentwogateelectrodes

arrangedinatopandbottomgateconfiguration.Ascanofthetopgate

voltagegeneratesaresistancepeak inambiploarresponse.Theambi-

polarpeakisshiftedbythebottomgatevoltage,wheretheshiftrate

dependsonthegraphitethickness.Thethickness-dependentpeakshift

wasclarifiedintermsoftheinter-layerscreeninglengthtotheelectric

field inthedouble-gatedgraphitefilm.Thescreeninglengthof1.2nm

wasexperimentallyobtained.[DOI:10.1143/APEX.1.034007]

1 RIKEN,Wako,Saitama351-0198,Japan2 CREST,JapanScienceandTechnologyAgency,Kawaguchi,Saitama332-0012,Japan3 InterdisciplinaryGraduateSchoolofScienceandEngineering,TokyoInstituteofTechnology,

Midori-ku,Yokohama226-8502,Japan4 InstituteofPhysicsandTsukubaResearchCenterforInterdisciplinaryMaterialsScience,

UniversityofTsukuba,Tsukuba,Ibaraki305-8571,Japan5 AdvancedIndustrialScienceandTechnology,Higashi,Tsukuba,Ibaraki305-8568,Japan* E-mailaddress:[email protected]


A Heterojunction Photodiode Operating at Inorganic Nanosheet InterfacesHisakoSato,KentaroOkamoto1,KenjiTamura2,HirohisaYamada2,KazukoSaruwatari,ToshihiroKogure,andAkihikoYamagishi1,2,*

(ReceivedNovember12,2007;acceptedFebruary4,2008;publishedonlineFebruary22,2008)

Aheterojunctionphotodiodewasfabricatedbyformingtwocontact

regionsonaglasssubstrate:onesidewasacastfilmofperovskite-type

niobate[(CH3)3NHSr2Nb3O10]asan-typephotosemiconductorandthe

othersideacastfilmofZn-saponite(Na0.96[Si7.18Al0.64]Zn6.20O20(OH)2)as

ap-typesemiconductorunderoxygenatmosphere.Diode-typecurrent–

voltagecharacteristicswereobtainedunder the illuminationof light

(340nm)andoxygenatmosphere (1atm)at25 –100°C.The interfa-

cialstructurewasstudiedbymeansoffocusedion-beamandtransmis-

sionelectronmicroscopytechniques,confirmingthecontactofthetwo

differentnanosheetsonananometerscale.Theresultsarediscussedon

thebasisofthenanosheetbandstructures.

[DOI:10.1143/APEX.1.035001]

GraduateSchoolofScience,TheUniversityofTokyo,Tokyo113-0013,Japan1 FacultyofScience,OchanomizuUniversity,Tokyo112-8610,Japan2 PhotocatalyticMaterialsCenter,NationalInstituteforMaterialsScience,Tsukuba,Ibaraki




Influence of Substrates on Initial Growth of Diamond-Like Carbon FilmsNobutoYasui1,2,HiroshiInaba1,andNaotoOhtake3

(ReceivedNovember24,2007;acceptedFebruary11,2008;publishedonlineFebruary29,2008)

We investigated the influenceofsubstratematerialsonbonding

structureofdiamond-likecarbon (DLC) films, fabricatedby filtered

cathodicvacuumarc,byusingX-rayphotoelectronspectroscopyand

secondary ionmassspectroscopy.Twokindsofsubstratematerials,Si

andNiFe,wereevaluated.Theresultsshowedthatsp3ratioofDLCfilms

onNiFewaslowerthanthatonSibyapproximately10%,andimplies

that thediffusionofNeandFe intoDLC films inhibits sp3bonding

formation.[DOI:10.1143/APEX.1.035002]

1 ProductionEngineeringResearchLaboratory,Hitachi,Ltd.,Yokohama244-0817,Japan2 DepartmentofMechanicalSciencesandEngineering,TokyoInstituteofTechnology,Tokyo

152-8552,Japan3 GraduateSchoolofEngineering,NagoyaUniversity,Nagoya464-8603,Japan


Near-Surface Defects in Boron-Doped Diamond Schottky Diodes Studied From Capacitance TransientsPierreMuret,JulienPernot,TokuyukiTeraji1,andToshimichiIto2


Transientcapacitancespectroscopyofdeepenergy levels (DLTS) in

thebandgapofboron-dopedhomoepitaxialdiamonddisplaystwotypes

ofdefectwhentemperatureisraisedfrom250to650K.Thefirsttrapis

astronglyattractivecenterforholeswhilethesecondoneisrepulsive,

withrespectiveactivationenergiesof1.57and1.15eV.Concentration

profileisnon-monotonicforthefirsttrapandchangeswhenthediode

undergoesrepetitivetemperaturecycles.Analysisofall thedatashows

thatthedeepcentersfoundinthisstudycomefromstructuraldefects,

eventuallyassociatedwithachargedimpurity.

[DOI:10.1143/APEX.1.035003]

InstitutNéel,CentreNationaldelaRechercheScientifiqueandUniversitéJosephFourierBP166,38042GrenobleCedex9,France1 SensorMaterialsCenter,NationalInstituteforMaterialsScience,1-1Namiki,Tsukuba,

Ibaraki305-0044,Japan2 GraduateSchoolofEngineering,OsakaUniversity,2-1Yamada-oka,Suita,Osaka565-0871,

Japan


Nitrogen Gas Flow Driven Unintentional Incorporation of Al during the Growth of Dilute Nitride Semiconductor by Plasma-Assisted Molecular Beam EpitaxyShudongWu,MasakazuKato,MasayukiUchiyama,KotaroHigashi,FumitaroIshikawa,andMasahikoKondow(ReceivedJanuary30,2008;acceptedFebruary8,2008;publishedonlineFebruary29,2008)

Wereporttheunintentional incorporationofAlduringthegrowth

ofmolecularbeamepitaxyusingRFplasmasource,drivenbyN2gas

flow.TheconcentrationsofN,Al,O,andCwithinGaNAs/GaAs/AlAs

structureareinvestigatedbysecondaryionmassspectrometry.Inspiteof

theclosedshutterofAlcell,weobserveAlincorporationwithaconcen-

trationupto1×1018cm-3 inGaNAs layerandcharacteristically in the

bottomsideGaAs.ItsconcentrationissolelydependentonN2gasflow

rate.Remarkably,theoperationoftheRFplasmahasnoimpactonthat.

CandOshowtheirconcentrationscorrespondingtotheextrinsicAl.The

complexinteractionsbetweenthoseelementspredictapossibleoriginof

materialdeteriorationsanddifficultyfortheprecisedopingcontrol.

[DOI:10.1143/APEX.1.035004]

GraduateSchoolofEngineering,OsakaUniversity,2-1Yamadaoka,Suita,Osaka565-0871,Japan


Difference in Reaction Schemes in Photolysis of Triphenylsulfonium Salts between ��nm and Dry/Wet ��nm ResistsYoshinoriMatsui*,HidekazuSugawara,ShuSeki,TakahiroKozawa,SeiichiTagawa**,andToshiroItani1(ReceivedJanuary11,2008;acceptedFebruary17,2008;publishedonlineMarch7,2008)

Chemicallyamplified (CA) resistsare important in the semicon-

ductorindustrybecauseoftheirhighordersofmagnitudeofsensitivity

enhancement.ThekeycomponentsofCAresistsareapolymerwithan

acidlabilegroupandaphotoacidgenerator(PAG)thatproducesanacid

uponexposuretoradiation.AlthoughthephotolysisofPAGshasbeen

intensivelystudied,thedifferenceinreactionschemesbetween248and

193nmresistshadnotbeenclarified.Inthiswork,wehavefocusedon

thereactionofPh2S•+,which isoneofthemajor intermediates inthe

photolysisoftriphenylsulfoniumtriflate. Itwasrevealedthatthediffer-

enceinreactionschemesbetween248and193nmresistsiscausedby

theionmolecularreactionsofapolymerradicalcationproducedbyelec-

trontransferfromthepolymertoPh2S•+.

[DOI:10.1143/APEX.1.036001]

TheInstituteofScientificandIndustrialResearch,OsakaUniversity,8-1Mihogaoka,Ibaraki,Osaka567-0047,Japan1 SemiconductorLeadingEdgeTechnologies,Inc.,16-1Onogawa,Tsukuba,Ibaraki305-8569,

Japan* Presentaddress:NECElectronicCorporation,1120Shimokuzawa,Sagamihara,Kanagawa

229-1198,Japan.E-mailaddress:[email protected]**E-mailaddress:[email protected]




Correlation Imaging of Magnetic Recorded Patterns and Grain Structures of Perpendicular Magnetic-Recording MediaYoshioTakahashi(ReceivedJanuary7,2008;acceptedFebruary8,2008;publishedonlineFebruary29,2008)

Anobservation technique to imagepolycrystallineandmagnetic

structuresat the samesub-micronareaofperpendicularmagnetic-

recordingmediahasbeendeveloped.Thegranulargrainstructuresand

magneticallyrecordedbitpatternswereimagedbytransmissionelectron

microscopyandmagneticforcemicroscopy,respectively.Thesmallguide

marksfabricatedonadisksamplewithafocusedionbeamapparatus

wereusedforaligningtheimageswitheachother.Byapplyingthistech-

niquetoanalyzethemagneticallyrecordedCoCrPtSiOthinfilmlayersof

aharddiskmedium,thecorrelationbetweenthepositionsoftheclus-

teredgrainsandthepercolationofthemagneticbitpatternscouldbe

discussed.[DOI:10.1143/APEX.1.037001]

CentralResearchLaboratory,Hitachi,Ltd.,Kokubunji,Tokyo185-8601,Japan


New Technique of Manipulating a Protein Crystal Using Adhesive MaterialTomoyaKitatani1,2,ShigeruSugiyama1,2,HiroyoshiMatsumura1,2,3,HiroakiAdachi1,2,3,HiroshiY.Yoshikawa1,2,SyouMaki1,2,SatoshiMurakami2,3,4,TsuyoshiInoue1,2,3,YusukeMori1,2,3,andKazufumiTakano1,2,3,*


WehavedevelopedCrystalCatcher,anewdeviceformanipulating

proteincrystals.CrystalCatcherdirectlycapturesacrystalwithanadhe-

sive.Theeasyandstableremovalofaproteincrystal fromadrophas

beenachievedusingtheCrystalCatcher.Thecrystalpickeduponthe

CrystalCatcher ispositioned in thecryostreamonagoniometerand

flash-cooled.Variousproteincrystalscanbecapturedandmounted

withoutcausingsignificantdamage.Thisnewapproachwill replace

nylonloopsforpickingupproteincrystals.

[DOI:10.1143/APEX.1.037002]

1 GraduateSchoolofEngineering,OsakaUniversity,2-1Yamadaoka,Suita,Osaka565-0871,Japan

2 CREST,JapanScienceandTechnologyAgency,2-1Yamadaoka,Suita,Osaka565-0871,Japan

3 SOSHOInc.,1-6-18Honmachi,Chuo-ku,Osaka541-0053,Japan4 InstituteofScientificandIndustrialResearch,OsakaUniversity,8-1Mihogaoka,Ibaraki,

Osaka567-0047,Japan* E-mailaddress:[email protected]


Enhanced Transfection Efficiency in Laser-Induced Stress Wave-Assisted Gene Transfer at Low Laser Fluence by Increasing Pressure ImpulseShintaTakano,ShunichiSato1,*,MitsuhiroTerakawa,HiroshiAsida1,HideyukiOkano2,andMinoruObara(ReceivedDecember21,2007;acceptedFebruary11,2008;publishedonlineFebruary29,2008)

To improvetransfectionefficiencyingenedeliverybasedonnano-

secondpulsedlaser-inducedstresswaves,weexamineddifferenttypes

oftransparentmaterials,apoly(ethyleneterephthalate)sheet,poly(vinyl

alcohol)gel,andwater,whichwereplacedonalasertargetforplasma

confinement.Wefoundthattheuseofwaterwasmosteffectivefor

maintaininga largepressure impulseduringmultipulse laser irradiation

and,asaresult,hightransfectionefficiencywasdemonstrated inrat

skinin vivoatarelativelylowlaserfluenceof0.7J / cm2.Atthisfluence,

steadylasertransmissionthroughquartzfiberswasconfirmed,allowing

endoscopicapplicationofourgenedeliverytechnique.

[DOI:10.1143/APEX.1.038001]

DepartmentofElectronicsandElectricalEngineering,KeioUniversity,3-14-1Hiyoshi,Kohoku-ku,Yokohama223-8522,Japan1 DivisionofBiomedicalInformationSciences,NationalDefenseMedicalCollegeResearch

Institute,3-2Namiki,Tokorozawa,Saitama359-8513,Japan2 DepartmentofPhysiology,KeioUniversitySchoolofMedicine,35Shinanomachi,Shinjuku-

ku,Tokyo160-8582,Japan* E-mailaddress:[email protected]


Compositional Dependence of Nonpolar m-Plane InxGa�-xN/GaN Light Emitting DiodesHisashiYamada*,KenjiIso,MakotoSaito,HisashiMasui,KenjiFujito1,StevenP.DenBaars,andShujiNakamura(ReceivedFebruary12,2008;acceptedMarch3,2008;publishedonlineMarch21,2008)

Characteristicsofm-plane InGaN/GaNlightemittingdiodes (LEDs)

with various indiumcompositionswere investigated.X-raydiffrac-

tionrevealed that indiumcompositions in the InGaNmultiquantum

wells (MQWs)onm-planesubstratewere2–3timeslowerthanthose

onc-planesubstrate.Theopticalpolarizationratio form-planeLEDs

increasedfrom0.27to0.89withincreasingemissionwavelengthfrom

383to476nmduetocompressivelystrainedInGaNQWs.Theoutput

powerofelectroluminescencedecreasedabove400nmalthoughpolar-

ization-relatedinternalelectricfieldswereeliminated.

[DOI:10.1143/APEX.1.041101]

MaterialsDepartment,UniversityofCalifornia,SantaBarbara,CA93106,U.S.A.1 OptoelectronicsLaboratory,MitsubishiChemicalCo.,Ltd.,1000Higashi-Mamiana,Ushiku,




Hydrogen Sensing Characteristics of a Pd/AlGaN/GaN Schottky DiodeTsung-HanTsai,Huey-IngChen1,Kun-WeiLin,Ching-WenHung,Chia-HaoHsu,Tzu-PinChen,Li-YangChen,Kuei-YiChu,Chung-FuChang,andWen-ChauLiu*

(ReceivedFebruary29,2008;acceptedMarch12,2008;publishedonlineApril11,2008)

In thispaper, the interestinghydrogen sensingpropertiesofa

Pd-gateAlGaN/GaNSchottkydiodeareinvestigated.Asignificantlylow

detectionlimitof850ppbH2/airgascanbeobservedwithincreasingthe

temperatureto423K.Theexperimentalresults indicatethathydrogen

moleculescausegreatinfluencesonthediodebreakdownvoltage.Also,

thediodeexhibitsanultrahighsensingresponseof2.04×105at423K

whenexposuretoa9660ppmH2/airgas.Thetransientresponsetime

andreversibilityofthestudieddevicecanbeimprovedbyincreasingthe

operatingtemperature.[DOI:10.1143/APEX.1.041102]

InstituteofMicroelectronics,DepartmentofElectricalEngineering,NationalCheng-KungUniversity,1UniversityRoad,Tainan,Taiwan70101,R.O.C.1 DepartmentofChemicalEngineering,NationalCheng-KungUniversity,1UniversityRoad,

Tainan,Taiwan70101,R.O.C.* E-mailaddress:[email protected]


Enhanced Conversion Efficiencies of Cu�ZnSnS�-Based Thin Film Solar Cells by Using Preferential Etching TechniqueHironoriKatagiri,KazuoJimbo,SatoruYamada,TsuyoshiKamimura,WinShweMaw,TatsuoFukano1,*,TadashiIto1,andTomoyoshiMotohiro1

(ReceivedNovember12,2007;acceptedMarch7,2008;publishedonlineApril4,2008)

Cu2ZnSnS4 (CZTS) thin film solar cellshavebeen fabricatedby

co-sputteringtechniqueusingthreetargetsofCu,SnS,andZnS.CZTS-

basedthinfilmsolarcellsover6.7%efficiencywereobtainedforthe

firsttimebysoakingtheCZTSlayerontheMocoatedsoda-limeglass

substrateindeionizedwater(DIW)afterformingtheCZTSlayer. Itwas

foundthatDIW-soakinghadtheeffectofpreferentialetching,which

eliminatedselectivelymetaloxideparticlesintheCZTSlayer,byelectron

probeX-raymicroanalysis.[DOI:10.1143/APEX.1.041201]

DepartmentofElectricalandElectronicSystemsEngineering,NagaokaNationalCollegeofTechnology,888Nishikatakai,Nagaoka,Niigata940-8532,Japan1 MaterialsDepartment,ToyotaCentralResearchandDevelopmentLaboratoriesInc.,

Nagakute,Aichi480-1192,Japan* E-mailaddress:[email protected]


Enhancement-Mode ZnO Thin-Film Transistor Grown by Metalorganic Chemical Vapor DepositionJungyolJo*,OgweonSeo1,HyoshikChoi,andByeonggonLee2

(ReceivedJanuary23,2008;acceptedMarch21,2008;publishedonlineApril11,2008)

Wedevelopedamethodtocontrol thresholdvoltageandon/off

ratioofZnOthin-filmtransistor (TFT)grownbymetalorganicchemical

vapordeposition(MOCVD).ZnOusuallyshowsoxygendeficiency,which

showsupasn-typedefectsofzincinterstitialoroxygenvacancy.Inorder

toreduce thesedefects,weallowedsufficientoxidation timeduring

growth. Insteadofone longoxidation step,we repeated thin-layer

growthandoxidation,untildesiredthickness isachieved.Byusingthis

method,wecouldobtainhighqualityZnOTFTbyMOCVD.OurZnOTFT

grownat450°Cshowed15cm2/(Vs)mobilityand107on/offratio,with

+5Vthresholdvoltage,whichenablesenhancementmodeTFTopera-

tion.[DOI:10.1143/APEX.1.041202]

DepartmentofElectricalandComputerEngineering,AjouUniversity,Suwon443-749,Korea1 NanoFabricationTechnologyCenter,SamsungAdvancedInstituteofTechnology,Suwon

440-600,Korea2 CDACo.,Ltd.,Yangjaedong,Seoul137-893,Korea* E-mailaddress:[email protected]


Enhanced Temperature Characteristics of InGaAs/InAlGaAs Multi-Quantum-Well Lasers on Low-In-Content InGaAs Ternary SubstratesTakeshiFujisawa*,MasakazuArai,TakaakiKakitsuka,TakayukiYamanaka,YasuhiroKondo,andHiroshiYasaka(ReceivedFebruary14,2008;acceptedMarch21,2008;publishedonlineApril11,2008)

Temperaturecharacteristicsofmulti-quantum-well lasersonInGaAs

ternary substratesare investigated.Byusing InAlGaAsbarriersand

low-In-content InGaAssubstrates, thecharacteristic temperatureof

thelasercanreachashighas150Kbetween25and85°Cduetothe

enhancementofthematerialgain.Calculatedcharacteristictemperatures

areingoodagreementwiththoseobtainedbyexperiment,showingthe

validityoftheresultspresentedhere.[DOI:10.1143/APEX.1.041203]

PhotonicsLaboratories,NTTCorporation,3-1Morinosato-Wakamiya,Atsugi,Kanagawa243-0198,Japan* E-mailaddress:[email protected]




X-ray Magnetic Circular Dichroism and Photoemission Study of the Diluted Ferromagnetic Semiconductor Zn�-xCrxTeYukiakiIshida1,*,MasakiKobayashi1,Jong-IlHwang1,YukiharuTakeda2,Shin-ichiFujimori2,TetsuoOkane2,KotaTerai2,YujiSaitoh2,YasujiMuramatsu2,AtsushiFujimori1,2,ArataTanaka3,HidekazuSaito4,andKojiAndo4


WehaveperformedX-raymagneticcirculardichroism(XMCD)and

valence-bandphotoemissionstudiesofthedilutedferromagneticsemi-

conductorZn1-xCrxTe.XMCDsignalsduetoferromagnetismandpara-

magnetismand/or superparamagnetismwereobservedat theCr2p

absorptionedge.Comparisonwithatomicmultipletcalculationssuggests

thatthemagneticallyactivecomponentoftheCrionwasdivalentunder

thetetrahedralcrystalfieldwithtetragonaldistortionalongthecrystal-

linea-,b-,andc-axes.Inthevalence-bandspectra,spectralweightnear

theFermi levelwasstronglysuppressed,suggestingtheimportanceof

Jahn–TellereffectandthestrongCoulombinteractionbetweentheCr

3delectrons.[DOI:10.1143/APEX.1.041301]

1 DepartmentofPhysics,UniversityofTokyo,Bunkyo,Tokyo113-0033,Japan2 SynchrotronRadiationResearchCenter,JapanAtomicEnergyAgency,Sayo,Hyogo

679-5148,Japan3 GraduateSchoolofAdvancedSciencesofMatter,HiroshimaUniversity,Higashihiroshima,

Hiroshima739-8530,Japan4 NanoelectronicsResearchInstitute,NationalInstituteofAdvancedIndustrialScienceand

Technology(AIST),TsukubaCentral2,1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan* E-mailaddress:[email protected]


Spin-Transfer Switching and Thermal Stability in an FePt/Au/FePt Nanopillar Prepared by Alternate Monatomic Layer DepositionKayYakushiji*,ShinjiYuasa,TaroNagahama,AkioFukushima,HitoshiKubota,ToshikazuKatayama,andKojiAndo(ReceivedFebruary14,2008;acceptedMarch12,2008;publishedonlineApril4,2008)

Wefabricatedacurrent-perpendicular-to-planegiantmagnetore-

sistance(CPP-GMR)nanopillarwitha1-nm-thickFePtfreelayerhaving

perpendicularanisotropyusingthealternatemonatomiclayerdeposition

method.Nanopillarsconsistingof[Fe(1monolayer (ML))/Pt (1ML)]n (n:

thenumberofthealternationperiod)ferromagnetic layersandanAu

spacer layershowedspin-transfer inducedswitchingatroomtempera-

ture.Anaveragecritical switchingcurrentdensity (Jc0)of1.1×107A/

cm2withalargethermalstabilityparameter(Δ)of60wasobtainedina

nanopillarwithafree-layerthicknessof1.02nm(n=3)andapillardiam-

eterof110nm.Theultrathinfree-layerwithhighperpendicularanisot-

ropyiseffectivetoobtainbothlargeΔandsmallJc.

[DOI:10.1143/APEX.1.041302]

NanoelectronicsResearchInstitute,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan* E-mailaddress:[email protected]


Reduction of Optical Loss in Hydrogenated Amorphous Silicon/Crystalline Silicon Heterojunction Solar Cells by High-Mobility Hydrogen-Doped In�O� Transparent Conductive OxideTakashiKoida*,HiroyukiFujiwara,andMichioKondo(ReceivedFebruary22,2008;acceptedMarch1,2008;publishedonlineMarch21,2008)

Hydrogen-dopedIn2O3(IO:H)filmswithhighelectronmobilityand

improvednear-infraredtransparencyhavebeenappliedasatransparent

conductingoxide (TCO)electrode inhydrogenatedamorphoussilicon

(a-Si:H)/crystallinesiliconheterojunctionsolarcells.Theincorporationof

IO:H,insteadofconventionalSn-dopedIn2O3,improvedtheshort-circuit

currentdensity (Jsc)and the resultingconversionefficiency.Detailed

opticalanalysisofthesolarcellsrevealedthattheimprovementinJsc is

duetothereductionofreflectionlossattheTCO/a-Si:Hinterfaceand

lessopticalabsorptionintheTCOlayer.[DOI:10.1143/APEX.1.041501]

ResearchCenterforPhotovoltaics,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),Central2,1-1-1Umezono,Tsukuba,Ibaraki305-8568,Japan* E-mailaddress:[email protected]


Optically Controlled Bimorph Cantilever of Poly(vinylidene difluoride)YasuhiroMizutani,YukitoshiOtani,andNorihiroUmeda(ReceivedFebruary8,2008;acceptedFebruary29,2008;publishedonlineMarch21,2008)

Opticallydrivenactuatorsareanon-contactmethodfortheremote

applicationoflightenergy.Weproposeanewopticallydrivenactuator

thatemploysbimorphpoly(vinylidenedifluoride)(PVDF)cantilevers.PVDF

isaneffectivepolymerfromwhichtoprepareactuatorssinceithasboth

pyroelectricandpiezoelectricproperties.Wehaveproducedabimorph

cantilever fromaPVDFfilmwitha thinAgelectrodeononeside.A

bendingmodelof thePVDFcantileverhasbeenestablishedand its

bendingcharacteristicshavebeenexperimentallymeasured.Themecha-

nismcanbeexplainedbytaking intoconsiderationthemodeland its

dielectricbreakdown.[DOI:10.1143/APEX.1.041601]

TokyoUniversityofAgricultureandTechnology,Koganei,Tokyo184-8588,Japan


Microstructure Analysis of Solid-State Reaction in Synthesis of BaTiO� Powder Using Transmission Electron MicroscopeKeisukeKobayashi,ToshimasaSuzuki,andYouichiMizuno(ReceivedFebruary13,2008;acceptedFebruary29,2008;publishedonlineMarch21,2008)

Thekineticsandmechanismof thesolid-statereaction inBaTiO3

powder synthesiswere investigatedmicrostructurally.Anequimolar

mixtureofBaCO3andTiO2(rutile)powderscalcinatedat600and800°C

inairwasobservedbyusingtransmissionelectronmicroscopy (TEM).

Duringthereaction, layeredBaTiO3wasformedovertheTiO2particles

withastructurallyandcompositionallysharp interface.Thecrystallo-

graphicorientationrelationshipbetweenTiO2andBaTiO3wasuniversally

observedas[001]TiO2 // [11–0]BTO,(100)TiO2 // (111)BTO.Theperovskitephase

BaTiO3wasformedbyinwarddiffusionofbariumandoxygenionsinto

therutile lattice,maintaininga topotaxial relationshipwith therutile

structure.[DOI:10.1143/APEX.1.041602]

MaterialDevelopmentDepartment,TaiyoYudenCo.,Ltd.,5607-2Nakamuroda,Takasaki,Gunma370-3347,Japan



Annealing Effect of �0K-Class Superconductivity of Ca-Doped B�S�CuO�+δ in Bi-��0� PhaseRyozoYoshizaki1,2,*,TetsuyaNakajima1,MasayoshiTange1,**,andHiroshiIkeda1,2

(ReceivedJanuary15,2008;acceptedMarch1,2008;publishedonlineMarch28,2008)

Annealingeffectonmagneticpropertiesof superconductivity is

investigatedforthecrystalsofBi1.9CaySr1.9-yCuO6+δ(0≤y≤1.8)inBi-2201

phase. It is found thatcarrierdensity is reducedwithCadoping in

Ca-poorregionofy≤0.8. Incontrast, theexcessoxygenδ issaturated

withdopingatabout theoptimalTc inCa-richregionofy>0.8.The

resultsindicatepossibleoxygendeficiencieswithCadoping,whichgives

anewaspecttoamodelfortheappearanceof80K-classsuperconduc-

tivity.[DOI:10.1143/APEX.1.041701]

1 GraduateSchoolofPureandAppliedSciences,UniversityofTsukuba,Tsukuba,Ibaraki305-8571,Japan

2 CryogenicsDivision,ResearchFacilityCenterforScienceandTechnology,UniversityofTsukuba,Tsukuba,Ibaraki305-8571,Japan

* E-mailaddress:[email protected]**Presentaddress:DepartmentofMaterialsScienceandEngineering,FacultyofEngineering,

IwateUniversity,Morioka020-8551,Japan


Grain Size Increase and Field-Effect Mobility Enhancement of Pentacene Thin Films Prepared in a Low-Pressure H� AmbientTakamichiYokoyama*,ChangBumPark,KosukeNagashio,KojiKita,andAkiraToriumi(ReceivedFebruary6,2008;acceptedMarch3,2008;publishedonlineMarch21,2008)

Pentacenefilmsweregrownbythermalevaporationindifferentgas

atmospheresatarelatively lowvacuumofabout3Pa,andtheeffects

of thegasambientontheperformanceof thin filmtransistors (TFTs)

were investigated.TheTFTmobilityoffilmdeposited inH2wastwice

thetypicalvalueof0.3cm2/(V·s)forfilmdepositedinvacuum,whilethe

mobilityvaluesoffilmsdepositedinN2andO2werealmostthesame

asthatofvacuum-depositedfilm.Nosignificantchangesinon/offratio,

thresholdvoltage,orhysteresisbehaviorwereobserved inpentacene

TFTspreparedbyevaporationingasambient.Theimprovedmobilityof

pentacenefilmpreparedinH2canbeexplainedbyanincreaseingrain

sizeofthefirstlayerontheSiO2 /Sisubstrate.

[DOI:10.1143/APEX.1.041801]

DepartmentofMaterialsEngineering,SchoolofEngineering,TheUniversityofTokyo,7-3-1Hongo,Bunkyo,Tokyo113-8656,Japan* E-mailaddress:[email protected]


Photon Correlation in GaAs Self-Assembled Quantum DotsTakashiKuroda1,2,*,MarcoAbbarchi1,3,TakaakiMano1,KenjiWatanabe1,MasakazuYamagiwa1,KeijiKuroda1,KazuakiSakoda1,GiyuuKido1,NobuyukiKoguchi1,CarmineMastrandrea3,LuciaCavigli3,MassimoGurioli3,YoshihiroOgawa4,andFujioMinami4(ReceivedFebruary19,2008;acceptedMarch12,2008;publishedonlineApril4,2008)

Wereportonphotoncoincidencemeasurement inasingleGaAs

self-assembledquantumdot(QD)usingapulsedexcitationlightsource.

Atlowexcitation,whenaneutralexcitonlinewaspresentinthephoto-

luminescence(PL)spectrum,weobservednearlyperfectsinglephoton

emissionfroman isolatedQDat670nmwavelength.Forhigherexci-

tation,multiplePL linesappearedonthespectra,reflectingtheforma-

tionofexcitoncomplexes.Cross-correlationfunctionsbetweenthese

lines showedeitherbunchingorantibunchingbehavior,depending

onwhether therelevantemissionwas fromabiexcitoncascadeora

chargedexcitonrecombination.[DOI:10.1143/APEX.1.042001]

1 NationalInstituteforMaterialsScience,1-1Namiki,Tsukuba,Ibaraki305-0044,Japan2 PRESTO,JapanScienceandTechnologyAgency,4-1-8Honcho,Kawaguchi,Saitama

332-0012,Japan3 EuropeanLaboratoryforNon-LinearSpectroscopy,andDipartimentodiFisica,Universitàdi

Firenze,ViaSansone1,50019,SestoFiorentino,Firenze,Italy4 DepartmentofPhysics,TokyoInstituteofTechnology,O-okayama,Meguro,Tokyo



Terahertz-Wave Generation Using a �-Dimethylamino-N-methyl-�-stilbazolium tosylate Crystal Under Intra-Cavity ConditionsTakayukiShibuya1,2,TakuyaAkiba1,KojiSuizu1,HirohisaUchida3,ChikoOtani2,andKodoKawase1,2


We succeeded ingenerating terahertzwavesusingdifference-

frequencygeneration (DFG) inanorganic4-dimethylamino-N-methyl-

4-stilbazoliumtosylate(DAST)crystalunder intra-cavityconditions.We

constructedadualwavelengthoutputopticalparametricoscillator(OPO)

withtwopotassiumtitaniumoxidephosphate(KTP)crystalsfortheDFG

pumpingsource,andplacedtheDASTcrystal insidetheOPOcavityto

actasanonlinearwavelengthconversionelement.Ourexperimental

measurementsconfirmedthat intra-cavitygenerationwaspossibleand

thattheoutputlevelwasapproximatelythesameasthatofnormalexci-

tationusingtheexternalOPOoutput.[DOI:10.1143/APEX.1.042002]

1 NagoyaUniversity,Furo-cho,Chikusa-ku,Nagoya464-8603,Japan2 RIKEN,Aramaki-Aoba,Aoba-ku,Sendai980-0845,Japan3 DaiichiPureChemicalsCo.,Ltd.,Koyodai,Ryugasaki,Ibaraki301-0852,Japan




Frequency Increase of Resonant Tunneling Diode Oscillators in Sub-THz and THz Range Using Thick Spacer LayersNaomichiKishimoto1,SafumiSuzuki1,AtsushiTeranishi,1andMasahiroAsada1,2,*


Weobtainedfrequencyincreaseofresonanttunnelingdiode(RTD)

oscillatorsusing thick spacer layersat thecollector in sub-terahertz

range.Thisisattributedtoreductionofparasiticcapacitanceduetothe

increaseofspacer layer thickness.Theoscillationfrequency increased

from325to425GHzbythechangeofspacerlayerthicknessfrom5to

45nminreasonableagreementwiththeoreticalcalculation.Frequency

switchingwithbiasdirectionwasalsoobtainedforanRTDhavingan

asymmetric structurewith the thicknessof thecollectorandemitter

spacerlayersof30and5nm,respectively.Theoscillationfrequencywas

394GHzunder forwardbias,whereas336GHzunder reversebias in

whichtheroleoftheemitterandcollectorspacerswasexchanged.

[DOI:10.1143/APEX.1.042003]

1 InterdisciplinaryGraduateSchoolofScienceandEngineering,TokyoInstituteofTechnology,2-12-1-S9-3O-okayama,Meguro-ku,Tokyo152-8552,Japan

2 CREST,JapanScienceandTechnologyAgency,2-12-1-S9-3O-okayama,Meguro-ku,Tokyo152-8552,Japan



Time-Resolved Investigation of Nanosecond Crystal Growth in Rapid-Phase-Change Materials: Correlation with the Recording Speed of Digital Versatile Disc MediaYoshimitsuFukuyama1,NobuhiroYasuda1,JungeunKim1,HarunoMurayama1,YoshihitoTanaka1,2,ShigeruKimura1,KenichiKato1,2,ShinjiKohara1,YutakaMoritomo1,3,ToshiyukiMatsunaga4,RieKojima4,NoboruYamada4,HitoshiTanaka1,2,TakashiOhshima1,2,andMasakiTakata1,2,5,*


Thecrystallizationprocess indigitalversatiledisc(DVD)mediawas

investigatedusingatime-resolvedX-raydiffractionapparatuscoupled

with in situphotoreflectivitymeasurement.Thetimeprofilesofcrys-

tallizationwere foundtobeconsistentwith thechanges inphotore-

flectivity.Thephasechangeswerecharacterizedbythestartandend

time;90±1and273±1ns forGe2Sb2Te5,and85±1and206±1ns for

Ag3.5In3.8Sb75.0Te17.7, respectively. The faster crystallization time in

Ag3.5In3.8Sb75.0Te17.7isascribedtoitscharacteristiccrystallizationprocess;

itsX-raydiffractionprofileshowsasignificantsharpeningduringthe

crystallizationprocess,whereasthepeakwidthofGe2Sb2Te5remained

unchanged.Thepresentfindingssuggestthatcrystalgrowthcontrol is

anotherkeyfordesigningfasterphase-changematerials.

[DOI:10.1143/APEX.1.045001]

1 JapanSynchrotronRadiationResearchInstitute/SPring-8,1-1-1Kouto,Sayo-cho,Sayo-gun,Hyogo679-5198,Japan

2 SPring-8/RIKEN,1-1-1Kouto,Sayo-cho,Sayo-gun,Hyogo679-5148,Japan3 TheGraduateSchoolofPureandAppliedSciences,UniversityofTsukuba,Tennodai,

Tsukuba,Ibaraki305-8571,Japan4 MatsushitaElectricIndustrialCo.,Ltd.,3-1-1Yagumo-Nakamachi,Moriguchi,Osaka

570-8501,Japan5 DepartmentofAdvancedMaterialsScience,SchoolofFrontierSciences,TheUniversityof

Tokyo,5-1-5Kashiwanoha,Kashiwa,Chiba277-8561,Japan* E-mailaddress:[email protected]


Super-High Brightness and High-Spin-Polarization PhotocathodeXiuguangJin,NaotoYamamoto1,YasuhideNakagawa1,AtsushiMano1,TakanoriKato,MasatoshiTanioku,ToruUjihara,YoshikazuTakeda,ShojiOkumi1,MasahiroYamamoto1,TsutomuNakanishi1,TakashiSaka2,HiromichiHorinaka3,ToshihiroKato4,TsuneoYasue5,andTakanoriKoshikawa5


Usinganewlydevelopedtransmission-typephotocathode,anelec-

tronbeamof super-highbrightness [(1.3±0.5)×107A·cm-2·sr-1]was

achieved.Moreover, the spin-polarizationwasashighas90%.We

fabricatedatransmission-typephotocathodebasedonaGaAs–GaAsP

strainedsuperlatticeonaGaPsubstrateinordertoenhancethebright-

nessandpolarizationgreatly. Inthissystem,alaserbeamis introduced

throughthe transparentGaPsubstrate.Thebeam is focusedon the

superlatticeactive layerwitha short focal length lens.Excitedelec-

tronsaregeneratedinasmallareaandextractedfromthesurface.The

shrinkageoftheelectrongenerationarea improvedthebrightness. In

addition,aGaAslayerwasinsertedbetweentheGaPsubstrateandthe

GaAsPbufferlayertocontrolthestrainrelaxationprocessintheGaAsP

buffer layer.Thisdesign for straincontrolwaskey inachievinghigh

polarization(90%)inthetransmission-typephotocathode.

[DOI:10.1143/APEX.1.045002]

GraduateSchoolofEngineering,NagoyaUniversity,Furo-cho,Chikusa-ku,Nagoya464-8603,Japan1 GraduateSchoolofScience,NagoyaUniversity,Furo-cho,Chikusa-ku,Nagoya464-8602,

Japan2 ElectricalandElectronicsEngineering,DaidoInstituteofTechnology,10-3Takiharu-cho,

Minami-ku,Nagoya457-8530,Japan3 GraduateSchoolofEngineering,OsakaPrefectureUniversity,1-1Gakuen-cho,Naka-ku,

Sakai599-8531,Japan4 DaidoSteelCo.,Ltd.,2-30Daido-cho,Minami-ku,Nagoya457-8545,Japan5 FundamentalElectronicsResearchInstitute,AcademicFrontierPromotionCenter,Osaka

Electro-CommunicationUniversity,18-8Hatsu-cho,Neyagawa,Osaka572-8530,Japan


Self-Separation of a Thick AlN Layer from a Sapphire Substrate via Interfacial Voids Formed by the Decomposition of SapphireYoshinaoKumagai1,*,JumpeiTajima1,MasanariIshizuki1,2,ToruNagashima3,HisashiMurakami1,KazuyaTakada3,andAkinoriKoukitu1

(ReceivedMarch4,2008;acceptedMarch21,2008;publishedonlineApril11,2008)

AtechniqueforseparatingathickAlNlayergrownbyhydridevapor

phaseepitaxy(HVPE)ona(0001)sapphiresubstratewasdeveloped.By

heattreatmentat1450°CinagasflowcontainingH2andNH3,many

voidscouldbeformedattheinterfacebetweenathin(100nm)AlNlayer

grownat1065°Candthesapphiresubstratedueto thepreferential

decompositionofsapphire.Duringthecoolingprocessafterthesubse-

quentgrowthofathick(85µm)AlNlayer,thethickAlNlayerseparated

fromthesapphiresubstratewiththeaidof the interfacialvoids.The

freestandingAlNsubstratethusobtainedhadasmooth(0001)surface,

adislocationdensityof1.1×109cm-2,andanoptical transparencyfor

wavelengthsabove208.1nm.[DOI:10.1143/APEX.1.045003]

1 DepartmentofAppliedChemistry,GraduateSchoolofEngineering,TokyoUniversityofAgricultureandTechnology,2-24-16Naka-cho,Koganei,Tokyo184-8588,Japan

2 ResearchandDevelopmentDivision,TokuyamaCorporation,ShibuyaKonnoBldg.,3-3-1Shibuya,Shibuya-ku,Tokyo150-8383,Japan

3 TsukubaResearchLaboratories,TokuyamaCorporation,40Wadai,Tsukuba,Ibaraki300-4247,Japan




Determination of the Twist Angle of GaN Film by High Resolution X-ray DiffractionHongtaoLi,YiLuo*,LaiWang,GuangyiXi,YangJiang,WeiZhao,andYanjunHan(ReceivedMarch5,2008;acceptedMarch21,2008;publishedonlineApril11,2008)

Asanazimuthalscanmethod,ϕ-scanspreformedbyX-raydiffrac-

tionareusuallyusedtodeterminethetwistangleinGaNfilms.However,

bothtwistandtiltcontributetofullwidthathalfmaximum(FWHM)of

ϕ-scancurves.Sofarnomodelhasbeenproposedtodistinguishthe

contributionsoftiltandtwisttoFWHMofthesecurves.Ageometrical

modelispresentedtodistinguishtheircontributions,whichisveryimpor-

tanttopreciselydeterminethedislocationdensitiesinGaN.Basedonthis

model,FWHMofϕ-scanscanbeexpressedasasimpleexplicitfunction

oftheoriginaltwistangleandanadditionaltwistangleinducedbytilt.

Thesetwistanglesarethensimplyandeffectivelydeterminedforvarious

GaNfilmsaccordingtothissimplefunction,andareingoodagreement

withthosededucedfromω-scandatafitting.

[DOI:10.1143/APEX.1.045004]

StateKeyLaboratoryonIntegratedOptoelectronics/TsinghuaNationalLaboratoryforInformationScienceandTechnology,DepartmentofElectronicEngineering,TsinghuaUniversity,Beijing100084,China* E-mailaddress:[email protected]


Gas-Temperature-Dependent Characteristics of Cryo-Dielectric Barrier Discharge Plasma under Atmospheric PressureYuriNoma,JaiHyukChoi,SvenStauss,TakaakiTomai,andKazuoTerashima(ReceivedJanuary21,2008;acceptedMarch7,2008;publishedonlineMarch28,2008)

Inthepresentwork,cryo-dielectricbarrierdischarge(DBD)plasma

wasgeneratedcontinuouslybelowroomtemperaturedownto liquid

nitrogentemperature (296to78K)underatmosphericpressureusing

parallel indium –tin-oxide (ITO)-coatedelectrodes.Gas-temperature-

dependentoptical emission spectroscopy (OES)measurementsand

dischargepatternobservationofcryo-DBDplasmawereperformed. In

thecaseofheliumgas,thedischargemodeofcryo-DBDplasmachanged

fromfilamentarymodetoglowmodeasthegastemperaturedecreased.

Whenintroducingasmallamountofnitrogen inheliumgas, thefila-

mentarydischargemodepersistedupondecreasingthegastemperature,

althoughthedischargepatternchangedfromconcentricrings(296K)to

ahexagon-likepattern(78K).[DOI:10.1143/APEX.1.046001]

DepartmentofAdvancedMaterialsScience,GraduateSchoolofFrontierSciences,TheUniversityofTokyo,5-1-5Kashiwanoha,Kashiwa,Chiba227-8561,Japan


Discharge Characteristics of Microwave and High-Frequency In-Liquid Plasma in WaterShinfukuNomura,HiromichiToyota,ShinobuMukasa,YoshiyukiTakahashi,TsunehiroMaehara,AyatoKawashima1,andHiroshiYamashita(ReceivedJanuary31,2008;acceptedMarch12,2008;publishedonlineApril4,2008)

Theplasmainwater isgeneratedbyapplyinghigh-frequency(HF)

irradiationof27.12MHzormicrowave(MW)radiationof2.45GHzfrom

anelectrode.TheelectrodeisheatedbyjouleheatingbytheHForMW

irradiation,andvaporbubblesaregeneratedsimultaneously.Theplasma

isthenignitedinsidethebubblesontheelectrode.Theglowdischarge

plasmacanbemaintainedinspiteofatmosphericpressureduetothe

coolingeffectoftheliquiditself.Theelectrontemperatureoftheplasma

generatedbythe27.12MHzradiationishigherthanthatgeneratedby

the2.45GHzradiation.[DOI:10.1143/APEX.1.046002]

GraduateSchoolofScienceandEngineering,EhimeUniversity,3Bunkyo-cho,Matsuyama790-8577,Japan1 DepartmentofEnvironmentalScienceforIndustry,EhimeUniversity,3-5-7Tarumi,

Matsuyama790-8566,Japan


Enhancement of Acid Production in Chemically Amplified Resist for Extreme Ultraviolet LithographyHirokiYamamoto,TakahiroKozawa*,SeiichiTagawa**,HirotoYukawa1,MitsuruSato1,andJunichiOnodera1

(ReceivedNovember27,2007;acceptedFebruary29,2008;publishedonlineMarch21,2008)

Thetrade-offamongsensitivity,resolution,andlineedgeroughness

(LER)isthemostseriousproblemfortherealizationofextremeultraviolet

(EUV)lithography.Asolutiontothisproblemistheenhancementofacid

generationefficiencyperunitvolume.InchemicallyamplifiedEUVresists,

nottheacidgeneratorsbutthepolymermainlyabsorbsEUVphotons.

ThesecondaryelectronsgeneratedbyEUVabsorptionsensitizetheacid

generators.Therefore,anincreaseinthepolymerabsorptioncoefficient

isexpectedtoleadtotheenhancementofacidproduction.Theincor-

porationof fluorineatoms isapromisingwayfor the increase in the

absorptioncoefficientofEUVresists.However,fluorinatedcompounds

decreasetheacidgenerationefficiencybyinterferingwiththereaction

ofacidgeneratorswith low-energyelectrons.We investigatedwhich

effectprevails inacidgeneration.Usingaspectroscopicmethod,itwas

confirmedthattheincorporationoffluorineatomsleadstoanincrease

inacidgenerationefficiencyperunitvolume.

[DOI:10.1143/APEX.1.047001]

TheInstituteofScientificandIndustrialResearch,OsakaUniversity,8-1Mihogaoka,Ibaraki,Osaka567-0047,Japan1 TokyoOhkaKogyoCo.,Ltd.,1590Tabata,Samukawa,Koza,Kanagawa253-0114,Japan* E-mailaddress:[email protected]**E-mailaddress:[email protected]




Organic Contaminant Detection of Silicon Wafers Using Negative Secondary Ions Induced by Cluster Ion ImpactsKouichiHirata*,YuichiSaitoh1,AtsuyaChiba1,andKazumasaNarumi2(ReceivedJanuary24,2008;acceptedMarch7,2008;publishedonlineMarch28,2008)

Emission yields of carbon and hydrogenated carbon cluster

secondaryionsCpHq±(p≥1,q≥0)originatingfromorganiccontaminants

onasiliconwaferarecomparedbetweenmonoatomic(0.5-MeV/atom

C1+)andcluster ion (0.5-MeV/atomC8

+) impactsusingtime-of-flight

(TOF)secondaryionmassspectrometry.CpHq-fortheclusterionimpact

exhibitsthehighestemissionyieldperincidentatomamongCpHq±with

thesamepnumber.ThehighestrelativeCpHq-emissionyield for the

clusterionimpactreaches~20and~60timeshigherincomparisonwith

thoseofCpHq-andCpHq

+withthesamepnumberforthe impactof

themonoatomicionwiththesamevelocity,respectively.Combinationof

negativesecondaryionTOFmeasurementswithclusterimpactionization

isapromisingtoolforhighlysensitivedetectionoforganic-contaminants

onsiliconwafers.[DOI:10.1143/APEX.1.047002]

NationalMetrologyInstituteofJapan,NationalInstituteofAdvancedIndustrialScienceandTechnology(AIST),Tsukuba,Ibaraki305-8565,Japan1 DepartmentofAdvancedRadiationTechnology,TakasakiAdvancedRadiationResearch

Institute(TARRI),JapanAtomicEnergyAgency(JAEA),Takasaki,Gumma370-1292,Japan2 AdvancedScienceResearchCenter,JapanAtomicEnergyAgency(JAEA),Takasaki,Gumma



Erratum: “Local Synthesis of Tungsten Oxide Nanowires by Current Heating of Designed Micropatterned Wires”KeisukeNagato1,2,*,YusukeKojima1,KeigoKasuya3,HirokiMoritani1,TetsuyaHamaguchi1,andMasayukiNakao1

(ReceivedJanuary29,2008;acceptedMarch11,2008;publishedonlineMarch28,2008)

[DOI:10.1143/APEX.1.049201]

1 DepartmentofEngineeringSynthesis,SchoolofEngineering,TheUniversityofTokyo,7-3-1Hongo,Bunkyo-ku,Tokyo113-8656,Japan

2 ResearchFellowoftheJapanSocietyforthePromotionofScience,8Ichibancho,Chiyoda-ku,Tokyo102-8472,Japan

3 CentralResearchLaboratory,Hitachi,Ltd.,1-280Higashi-koigakubo,Kokubunji,Tokyo185-8601,Japan
