Nanosyd Annual Report 2008

Nano Center SouthThe Mads Clausen Institute

Alsion 2, 6400 Sønderborg

Denmark

Annual Report 2008

NanoSYD

Preface 3The team 2008 4The partners 6Achievements 8Facilities 12Projects 16Education 34Activities 35Nanoseminars 36Publications 38Presentations 48

Contents

1ANNUAL REPORT 2008

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NanoSYD

Preface

ANNUAL REPORT 2008

Welcome to the second issue of the annual re-port for NanoSYD. NanoSYD is a nanotechnol-ogy centre at the Mads Clausen Institute at the Faculty of Engineering, University of Southern Denmark. It is located at Alsion, an educational and cultural building complex in Sønderborg near the Danish/German border. NanoSYD hosts the SDU clean room as well as optical, and surface science laboratories.

NanoSYDs vision is

to bridge education, research and development in nano- and microtechnologies to develop nano- and microtechnology based innovative photonic and electromechanical devices. NanoSYDs mission is

to benefit the academic and industrial Southern Denmark with access to state-of-the art micro- and nanofabrication facilities including experimental and theoretical nanoscience- and technol-ogy.

18th of December 2008 the clean room at NanoSYD has been inaugurated with an official ceremony and a scientific workshop. The clean room is now ready for being used inside and outside SDU for education, research and processing projects.

Besides this opening, NanoSYD has focused activities in its second year on

- specifying the directions of nanotechnological and microtechnological research and development - finalizing the hook up of clean room equipment - finalizing working condition control of the clean room - setting up new cross-border and industry-academia networks

In its second year, the staff of NanoSYD could fortunately be extended by a number of very competent new co-workers. The presentations in the present report reflect this positive de-velopment, which I hope will continue in 2009.

Horst-Günter RubahnProfessor, Center leader

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NanoSyd team 2008Frank Balzer (1.1. - 31.12.) Dr., Associate Professor

Daniele Barettin (1.1. - 31.12.) PhD student

Kirill Bordo (1.9. - 31.12.) PhD student

Sylwia Dawidziuk (1.10. - 31.12.) Student assistant

Ralf Frese (1.1. - 31.7.) Dipl.Phys., PhD student

(1.8. - 31.12.) Postdoc

Betta Hansen (1.9. - 30.6.) Secretary

Jakob Kjelstrup-Hansen (1.1. - 31.12.) Assistant Professor

Igor Kornev (1.9. - 31.12) Associate Professor

Benny Lassen (1.1. - 31.12) Assistant Professor

Natasha Viegas Lopes Guest researcher

Morten Madsen (1.1. - 31.12) Cand.polyt., PhD student

Christian Maibohm (1.1. - 31.12.) PhD student

Zora Milde (1.7. - 31.12) Secretary (maternity cover)

Martin Nørgaard (1.1. - 31.12.) Cand.scient., ATAP (clean

room)

Giorgia Pellizzari (1.1. - 31.12.) Student assistant (web editor)

Mogens Petersen (1.1. - 31.12.) Engineer, TAP (clean room)

Horst-Günter Rubahn (1.1. - 31.12.) Dr. habil, Professor

Manuela Schiek (1.1. - 14.10.) Dr., Dipl.chem., postdoc

(15.10. - 31.12.) Assistant Professor

Luciana Tavares (1.9. - 31.12.) PhD student

Roana Melina de Oliveira (1.4. - 31.12.) PhD student

Kasper Thilsing-Hansen (1.1.- 31.12.) Chief technician (clean room)

Morten Willatzen (1.1. - 31.12.) Dr., Professor

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ANNUAL REPORT 2008

GUESTS

Vladimir G. Bordo (22.6.-3.8./12.10. - 22.11.) Dr.Sc., visiting scientist

Leszek Jozefowski (7.2.-1.3. /24.11.-19.12.) Dr., visiting scientist

Robert Alberti (14.1. - 12.2.) Consultant

(25.3. - 25.4.)

(25.6. - 28.7.)

(21.8. - 13.9.)

(26.10. - 16.12.)

Tomasz Kawalec (1.1. – 31.8.) Postdoctoral Associate

Jacek Fiutowski (1.2.-29.2.) Guest PhD

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Tomas Tamulevicius (28.1.-11.2. and 1.12. - 6.12.) Guest students

Asta Sileikate (28.1.-11.2. and 1.12. - 6.12.) Guest students

Partners universities and research institutes

NanoSYD

Aalborg University Department of Physics and Nanotechnology Contact persons: Thomas G. Pedersen, Kjeld Pedersen

Federal Agency of Materials Investigations Polymer DepartmentBAM, Berlin Contact person: Heinz Sturm University of Bochum Chemistry Department Contact person:Christof Wöll

Paul Drude Institute, Berlin Nanoaccoustics Contact person: Paolo Santos

Technical University of Denmark Microelectronic Center, COM, MAT Contact persons: Jesper Mørk, Peter Bøggild

University of Applied Sciences, Flensburg FB Technik Contact: Helmut Erdmann

Russian Academy of Sciences General Physics Institute Contact person: Vladimir G. Bordo

Technical University of Graz Institute of Physics Contact person: Rolanf Resel, Franz Kappel

Jagiellonian University, Cracow Faculty of Physics Contact person: Marek Szymonski University of Applied Sciences, Kiel IMST Contact person: Mohammed Es-Souni

Christian Albrechts University Kiel Multicomponent Materials Chair Contact persons: Franz Faupel, Michael Bauer

Kaunas University of Technology Institute of Physical Electronics Contact person: Sigitas Tamulevicius

Linz University Linz Institute for Organic Solar Cells (LIOS) Contact person: Serdar Sariciftci

Lund University Physics Department Contact person: Andreas Wacker

University of Oldenburg Center for Interface Science (CIS) Contact person: Katharina Al-Shamery

Wilfried Laurier University Mathematical Modelling GroupOntario, Canada Contact person: Roderick Melnik

University of Southern Denmark BMB, IFK, SENSE Contact persons: Luis Bagatolli, Per Morgen, John E. Østergaard

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AquaZ, Nordborg, Denamrk

Biomodics, Lyngby, Demanrk

Bioneer A/S, Hørsholm, Demanrk

Danfoss, Nordborg, Denmark

Diramo A/S, Nordborg, Denmark

Ibsen Photonics A/S, Farum, Denmark

Optaglio S.R.O., Czech Republik

PAJ Systemteknik A/S, Sønderborg, Denmark

Stensborg A/S, Roskilde, Denmark

ANNUAL REPORT 2008

University of Milano-Bicocca Institute of Physics Contact person: Gian Paolo Brivio

Wright State University Physics DepartmentOhio, Dayton, USA Contact person: Lok C. Lew Yan Voon

Tyndall Institute, Cork Island Contact person: Eoin O’Reilly

P.N. Lebedev Physical Institute, Moscow Contact person: Alexander Uskov

Universidad de los Anders, Colombia Contact person: Angela Camacho

Universidad National de Mexico Contact person: Rafael Bario

Laser Laboratorium Göttingen Contact Person: Jürgen Ihlemann

Partners companies

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Achievements

NanoSYD

THE CLEAN ROOM OPENING

On December 18 2008, the official opening of NanoSYD's clean room took place at Alsion. About a 100 guests were invited for lectures, international specialities, and exhibitions.

About 100 guests joined in celebrating the official opening of the clean room fa-cilities at Alsion on December 18. While they were arriving, a string quartet marked the beginning of the day with a beautiful intermezzo as a prelude to the event, with 'keynotes' from SDU's vice chancellor Jens Oddershede, Danfoss' CEO Jørgen Mads Clausen, the dean of the Technical Faculty, Per Michael Johansen, Sønderborg's mayor Jan Prokopek Jensen, as well as enthralling lectures about nano- and microtechnology.After lunch, guests could take a guided tour through the clean room and the labo-ratories, or look at the many posters, which were brought along, and the nano exhibi-tion, which shows a variety of products from everyday life equipped with nano-technology. The latter is permanently open to visitors.

The event continued with a minisymposium, and was finalised with a Christmas Concert by South Jut-land Symphony Orchestra.

Both Jyske Vestkysten and Der Nordschleswiger came to cover the opening.

Photo: Aghiad Ghazal

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February: ‘Organic Molecular Nanotechnology’, a paper marked as ‘concept article’ in SMALL, high-

lighted in the online forum ‘Nanowerk Spotlight’.

ANNUAL REPORT 2008

March: NanoSYD becomes part of the European NanoImprint

Factory, ‘Octopus’, an innovation consortium between Nano-

SYD/SDU, MIC/DTU, Micro Electronics Research Center,

Austin, Texas, Teknologisk Institut, G&O Skamatik A/S, NIL

Techonology ApS, Polyteknik A/S, Sense A/S, and Widex A/S,

led by Teknologisk Institut.

March: The book ‘Organic Nanostructures for Next Genera-

tion Devices’ appears in the Springer Series in Materials Sci-

ence , Vol. 101. Editors are Al-Shamery, Katharina; Rubahn,

Horst-Günter; Sitter, Helmut. It is a state-of-the-art update of

science and technology of organic nanofibres.

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NanoSYD

June: On June 3rd, the local committee for the European Structural Fond has decided to support a cross

border network between NanoSYD, University of Applied Sciences, Kiel and University of Applied Sci-

ences, Flensburg with a total amount of roughly 1 Million Euro.

The goal of the network is to establish a new microfluidic platform including advanced optical sensing for

detection of microbial contaminants – a so-called “lab-on-a-chip”. NanoSYD coordinates these activities,

which include basic research, technological development and educational efforts.

December: About 100 guests joined in celebrating the official opening of the clean room facilities at Al-

sion on December 18.

October: The book ‘Basics of Nanotechnology’ by Horst-Günter

Rubahn, appears at Wiley Interscience. It is the English version

of the book ‘Nanophysik und Nanotechnologie’, Teubner, 2004,

which also appeared in Danish as ‘Nanoteknologi’, Gyldendal,

2007.

August: at the Third summer school of the European doctorate in physics and chemistry of advanced

materials, held in Palanga (Lithuania), the poster ‘Templates patterned by Electron Beam Lithography for

integrated nanofiber growth’, by Roana Melina de Oliveira, Jakob Kjelstrup-Hansen, Morten Madsen and

Horst-Günter Rubahn, wins the Young scientist award given in recognition to the best poster presented.

Achievements

10

NanoSYD

THE CLEAN ROOM AT NanoSYD

The clean room at NanoSYD has educational, research, and processing purposes. It is equipped for process-

ing 4 inch silicon wafers. The equipment pool is especially suited for bulk micromachining of mechanical

micro- and nanostructures featuring double-sided lithography and deep silicon etching capabilities. This

enables the fabrication of e.g. beams and membranes. In addition, it allows the fabrication of hot embossing

stamps for e.g. microfluidic applications.

Patterning can be accomplished on a wafer scale by photolithography, and on smaller substrates with electron

beam lithography. Silicon nitride and poly-silicon can be deposited by low-pressure chemical vapor deposi-

tion, and silicon dioxide can be grown by thermal oxidation. Electron beam evaporation, and both DC and

RF sputtering facilitates the deposition of various metals and insulators. Soft materials can be deposited, e.g.

via a Langmuir Blodgett trough. Silicon, silicon dioxide, and silicon nitride can be processed by wet chemical

etching. In addition, a reactive ion etcher enables us for deep silicon etching of high aspect ratio structures.

The characterisation equipment includes scanning electron microscopy, atomic force microscopy, ellipsom-

etry, and various optical microscopy techniques, interference microscopy included. Back-end processing

includes dicing and wire bonding. The complete equipment list can be found on www.sdu.dk/nanosyd/.

Facilities

The Laboratories are comple-mentary to the clean room facilities. They focus on thin film deposition and photonics technology, with special empha-sis on laser materials treatment, spectroscopy, and near field optical technologies.

Surface Science Laboratory

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ANNUAL REPORT 2008

FIELDS OF INTEREST

Nano- and microtechnology devices based on Development of integration strategies based on

• Advanced sensing platforms • Fluidic alignment

• Micro- and nanofluidics • Soft lithography for transfer printing

• Lighting, lasing, sensing, frequency-transform-

ing, waveguiding photonic elements and com-

binations of those Nanolithographies including

e.g. hot embossing

• Nanolithographies including e.g. hot emboss-

ing

• Single element manipulation

• Microelectromechanical systems (MEMS)

• Ultrasonic components (theory)

The Laboratories are comple-mentary to the clean room facilities. They focus on thin film deposition and photonics technology, with special empha-sis on laser materials treatment, spectroscopy, and near field optical technologies.

Surface Science Laboratory

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THE OPTICS AND SURFACE SCIENCE LABORATORIES

The Laboratories are complementary to the clean room facilities. They focus on thin film deposition and photonics technology, with special emphasis on laser materials treatment, spectroscopy, and near field optical technologies.

Surface Science Laboratory (Block A, 3rd floor)

This laboratory hosts ultrahigh and high vacuum thin film deposition apparatus with state-of-the-art surface characterisation equipment. Ultrathin films and nanoaggregates from metals, semiconductors, and dielectrics can be grown, but focus is on the growth of discontinuous organic thin films. The labora-tory also hosts stations for micromanipulation of nanoaggregates, for electrical measurements, and for spectroscopy, as well as an excimer laser materials treatment station. Development of infrared light based sensor is performed in a separated section. A small workshop is associated the laboratory.

NanoSYD

Facilities

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ANNUAL REPORT 2008

Nanooptics Laboratory (Below clean room, basement)

This laboratory is equipped with an ultrafast laser source, a scanning near field optical microscope, spec-trometers, and a laser scanning microscope. Additional laser tables allow one to set up further optical experiments for performing, e.g. goniometric measurements.

Microscopy Laboratory (Block A, 3rd floor)

A combined inverted epifluorescence and atomic force microscope is the main equipment of this labora-tory. A second epifluorescence microscope with accompanying spectrometers allows for high resolution, spectrally resolved optical images of surfaces and surface structures.

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Frank Balzer

Projects

Self-assembly of thiophene/phenylene co-oligomers

For the deposition of organic semiconductors such as para-phenylenes or α-thiophenes on dielectric surfaces the very first steps of the growth are of paramount importance for the overall morphology. On several dielectric surfaces such as KCl, NaCl, KAP, and mica many of them assemble into organic nanowires, their alignment being driven by epitaxy. Often the growth starts with the formation of an epitaxial wetting layer, which not necessarily exhibits the bulk crystal structure. Low energy elec-tron diffraction (LEED) is one of the very few methods to investigate the crystalline structure of such a wetting layer. It is therefore applied thoroughly in the present project.

Vacuum deposition of the blue-green light-emitting thiophene/phenylene co-oligomer 2,5-di-4-bi-phenyl-thiophene (PPTPP) on muscovite mica leads to three types of aggregates, exemplarily shown in the AFM image in Fig. 1: mutually parallel needles from lying molecules of typically 50 nm height, clusters from lying molecules of the same mean height in between, and flat islands from up-right molecules, only a few nanometers tall. The morphology of the films depends both on the overall nominal thickness as well as on the deposition temperature. At room temperature short, mutually parallel needles form, whereas at 370 K well isolated needles grow. The growth direction is either along muscovite [110] or along [1-10], depending on the cleavage face.

Figure 1: (a) AFM image, 20 x 20 µm2, of 7.5 nm PPTPP deposited on muscovite mica, demonstrating the overall morphology. In (b) a cross section through the image is shown, depicting typical heights of the needles (“n”), flat islands (“i”), and clusters (all other peaks). The wetting layer is not visible in this image.

Low energy electron diffraction (LEED) provides information about the crystallinity of the underly-ing wetting layer. From muscovite mica a hexagonal pattern is observed. After deposition of PPTPP additional spots appear, Fig. 2(a), which stem from the wetting layer of lying molecules on the sur-face. All experimentally obtained LEED spots are reproduced in Fig. 2(b), assuming an appropriate superstructure matrix for a hexagonal muscovite surface unit cell. The integer numbers suggest a commensurate overlayer. The lengths of the corresponding PPTPP unit cell axes do not agree with any projection of the bulk unit cell due to the strong interaction of the molecules with the substrate. As for para-hexaphenylene the direction of the short unit cell axis is along the long fiber axis, i.e.

NanoSYD16

Related papers

[1] L. Kankate, F. Balzer, H. Niehus, H.-G. Rubahn, From Clusters to Fibers: Parameters for dis continuous p-6P thin film growth, J. Chem. Phys. 128 (2008) 084709.

[2] F. Balzer, M. Schiek, A. Lützen, H.-G. Rubahn, Self organized growth of organic thiophene- phenylene nanowires on silicate surfaces, submitted for publication (2009).

Low energy electron diffraction (LEED) provides information about the crystallinity of the underly-ing wetting layer. From muscovite mica a hexagonal pattern is observed. After deposition of PPTPP additional spots appear, Fig. 2(a), which stem from the wetting layer of lying molecules on the sur-face. All experimentally obtained LEED spots are reproduced in Fig. 2(b), assuming a superstruc-ture matrix for a hexagonal muscovite surface unit cell. The integer numbers suggest a commensurate overlayer. The lengths of the corresponding PPTPP unit cell axes do not agree with any projection of the bulk unit cell due to the strong interaction of the molecules with the substrate. As for para-hexaphenylene the direction of the short unit cell axis is along the long fiber axis, i.e. along [110] or [1-10].

Figure 2: (a) LEED pattern from PPTPP on muscovite mica, taken at an electron energy of Eel = 62 eV. Superstructure spots exist in addition to the hexagonal spots from the muscovite mica surface. The sample has been tilted so that the specular reflection is visible (short arrow). The long arrow points to one of the faint lines in between the lines of spots. In (b) a reciprocal lattice is presented, in which all the experimentally observed spots are reproduced. Circles represent diffraction spots from the substrate, squares spots from the organic overlayer. The (00) spot is set into the center (short arrow).The overall growth mechanism of the fibers, i.e. the formation of a wetting layer followed by cluster growth from lying molecules and coagulation of these clusters into needles, seems to be quite univer-sal for the muscovite mica substrates. Their growth directions are determined by two driving forces: epitaxy and alignment due to surface electric fields.

Up to now the growth experiments are conducted under rather ill defined conditions, i.e. air-cleaved muscovite and deposition under a poor vacuum of 10-7 mbar. In 2009 the deposition experiments will be repeated under UHV conditions (10-10 mbar) using in situ cleaved substrates to rule out the influence of defects on the substrate surface on the overall growth as well as on the fibers optical properties.

ANNUAL REPORT 2008 17

Leszek Jozefowski & Vladimir G. Bordo

Optical mode launching in nanofibers

Organic nanofibers can be important elements for future nanodevices with a large variety of opti-cal and optoelectronic properties. Their illumination by light can lead to photoluminescence or laser action. The intensity of scattered light as well as the electromagnetic energy that penetrates the nanofiber undergo enhancement when the incident radiation is in resonance with a nanofiber optical mode and the phase-matching condition is fulfilled. The mode structure is also reflected in the excitation polarization ratio. To understand these phenomena and, on the other hand, to predict them, one needs comprehensive information on optical modes which are supported by nanofibers. A thorough knowledge of the mode dispersion of a given nanofiber ensemble is therefore of paramount importance for applications in nanophotonics.

Fig. 1 shows the experimental set-up for observation of far-field light scattering from an array of mutually parallel nanofibers as well as their photoluminescence as a function of the light incidence angle. The photoluminescence intensity measured along the normal to the surface is represented in Fig. 2. Clear peaks in both TE and TM incident light polarizations, both below and above the criti-cal angle, are seen.

In order to describe the optical properties of a nanofiber grown on a substrate we use a model system represented by an infinite isotropic dielectric semicylinder placed on an ideally reflecting surface. The crossings between the dispersion curves of the nanofiber optical modes and the light line of the incident radiation signify the optical mode excitations which are displayed as peaks in the sample optical response. Additional analysis of the mode polarization properties allows one to identify the launched modes.

The obtained results provide detailed information about possible electromagnetic mode propagation in nanosized, needle-shaped aggregates and form also the basis for a new way of optically character-izing the morphology of sub-wavelength sized nanostructures via far field scattering. Further devel-opment of this technique by using a tunable light source should allow one to determine the actual dispersion curves of nanofibers. Due to its generic nature, the method discussed here is not limited to organic nanofibers but can be equally well applied to other kind of light emitting nanoaggregates.

NanoSYD18

Related papers

Figure 1: Experimental set-up. hwp, half-wave plate; p, polarize; ph, pinhole; mo, microscope objective; f, filter; pmt, photo-multiplayer. inset: fluorescence microscopy image of a sample domain.

Figure 2: Photoluminescence intensity mea-sured along the normal to the sample surface as a function of the angle of incidence. The incident wave polarization is indicated in the inset.

The approach described above will be further developed on the basis of the following two possibili-ties. (i) The optical modes of mutually parallel nanofibers deposited on a metal surface can be excited by surface plasmon polaritons propagating along the substrate surface. (ii) If a parallel array of nano-fibers is deposited on a grating those modes can be launched by virtue of incident light diffraction.

[1] J. Fiutowski, V. G. Bordo, L. Jozefowski, M. Madsen, and H.-G. Rubahn. Light scattering from an ordered array of needle-shaped organic nanoaggregates: Evidence for optical mode launching. Appl. Phys. Lett. 92, 073302 (2008).


Tomasz Kawalec & Christian Maibohm

Optical properties of nanocrystals

Optical properties of different kinds of nanocrystals were investigated. The research was focused on sec-ond harmonic generation (SHG) [1] and waveguiding processes [2]. SHG was measured in the regime of near-infrared femtosecond excitation in an inverted epifluorescence microscope. The waveguiding prop-erties were investigated in the far-field in the mentioned microscope and (preliminary) also in the near-field with a scanning near field optical microscope.

Strong SHG was found for PPTPP (2,5-di-biphenylthiophene) nanocrystals, deposited on both mica and KCL substrates. Note that the symmetric structure of bulk crystals prohibits such processes. However, it was excluded in the epifluorescence microscope that the SHG signal originates only from the supporting substrate. Hence, the signal must come from the interface of either nanofiber/air or nanofiber/substrate or it could have been generated via a non-cdntrosymmetric packing of the molecules.

SHG was also found and analysed for BAHP4 crystals (4-(Aminomethyl)-quarterphenylene) transferred from mica to glass.

Typical SHG signals for different ex-citation wavelengths for PPTPP on mica. The SHG peak is up to 100 times greater than the two-photon induced fluorescence.

In the epifluorescence microscope setup waveguiding in PPTPP nanocrystals was directly observed (fig-ure below, image size 100 µm).

NanoSYD20

Related papers

A SNOM-setup was constructed and tested, allowing one to measure the optical near-field of nanocrystals using evanescent wave excitation. The setup is designed to find the optimum conditions for light coupling to nanocrystals. The coupling of light is extremely important for the development of photonic micro-devices as well as for improvement of recently investigated random nano-lasers.

Image of PPTPP nanofibers on KCL substrate taken with a SNOM. On the left-hand side the topography is shown and on the right-hand side the optical near field image upon 633 nm non-evanescent excitation.

The work will be continued regarding both second harmonic generation and waveguiding measurements. In particular, SHG process will be investigated in a scanning laser microscope, which combined with AFM analysis, allows one to find the correlation between the morphology of the nanocrystals and the SHG process. This combination of characterization techniques should shed light on the origin of the efficient SHG process in PPTPP nanocrystals. In the optical near field regime, detailed analysis of coupling of light to nanocrystals is to be investigated.

[1] J. Brewer, M. Schiek, A. Lützen, K. Al-Shamery, and H.-G. Rubahn, Nano Lett. 6, 2656, 2006.

[2] F. Balzer, V.G. Bordo, A.C. Simonsen, and H.-G. Rubahn, Phys. Rev. B 67, 115408, 2003


Jakob Kjelstrup-HansenCharge Transport in Phenylene and Phenylene-Thiophene Nanofibers

An important figure-of-merit for organic semiconducting materials is the charge carrier mobility, which highly influences operational characteristics of a range of devices. For example, in organic light-emitting diodes, the process of generating light requires the transport of holes and electrons to the recombination zone from the anode and cathode, respectively. In solar cells, charge carriers need to be transported to and collected at the electrodes upon dissociation of photon generated electron-hole pairs. This project focuses on the investigation of charge transport in organic nanofibers made from various thiophene-phenylene co-oligomers to find suitable materials for such optoelectronic applications.

The charge transport properties of individual nanofibers made from three different types of molecules: para-hexaphenylene (p6P), 5,5´-di-4-biphenylyl-2,2´-bithiophene (PPTTPP), and 4-4´-di-2,2´-dithienyl-biphenyl (TTPPTT) have been investigated by electrical transport measurements. By fitting the measured data with the Mott-Gurney formula, the charge carrier mobility could be extracted. The Mott-Gurney formalism assumes bulk-limited current in the space-charge limited regime, which causes the extracted mobilities to be lower bounds of the true mobility. For the three types of fibers, we find mobilities in the range between 0.1 cm2 V-1 s-1 and 1 cm2 V-1 s-1. The figure shows a scanning electon microscope image of a TTPPTT nanofiber with two metal electrodes (part a) and the extracted mobilities from the electrical measurements (part b).

NanoSYD22

Related papers

In addition to the experimental measurements, the transport properties have been studied by density functional theory. Based on the Marcus formula, the carrier transfer rate has been found by calculation of the overlap of the molecular orbitals between two neighboring molecules and of the energy associated with the molecular relaxation that accompanies charge transfer. Agreement within an order of magnitude with our experimental results is found.

The charge carrier mobility can also be determined by electrical measurements in a field-effect transistor geometry, which can give more detailed information on the charge transport. This requires the fabrication of a suitable transistor substrate in the cleanroom and the development and test of a nanofiber integration method. The first generation transistor substrates have already been fabricated and measurements are on the way. In addition, contacting the nanofibers in a transistor geometry can provide better injection of both holes and electrons and can thereby make the fabrication of a light-emitting device possible.

[1] Jakob Kjelstrup-Hansen, Joseph E. Norton, Demetrio A. da Silva Filho, Jean-Luc Brédas, and Horst-Günter Rubahn, Charge-Transport Properties of para-Hexaphenlyene Nanofibers, Proceedings of the 8th IEEE International Conference on Nanotechnology, 2008, Arlington, Texas, USA

[2] Jakob Kjelstrup-Hansen, Joseph E. Norton, Demetrio A. da Silva Filho, Jean-Luc Brédas, and Horst-Günter Rubahn, Charge Transport in Phenlyene and Phenylene-Thiophene Nanofibers, submitted.


Morten WillatzenExciton States in Curved Nanowire Structures

Progress in semiconductor nanostructure growth has made it possible to design quantum-wire and quantum-dash structures of almost arbitrary shape and size. It is well-known experimentally and theoretically that spatial confinement strongly affects electronic and optical properties. Confinement effects have led to considerable improvement in, e.g., semiconductor lasers in terms of low threshold current, high modulation bandwidth, high differential gain, and small linewidth enhancement factor.

In 2008, we extended the analysis of curved quantum structures to consider the influence of excitonic couplings. A Hamiltonian matrix problem is formulated by expanding Eigenstates of the full (excitonic) problem into Eigenstates of the corresponding problem where excitonic effects are discarded. A case study of a nanowire of fixed total length and volume has been analyzed, constructed by interconnecting two straight sections via a 90-degree circular-bent section. It is verified that the groundstate excitonic binding energy is strongly affected by the radius-of curvature R of the circular section. In actual fact, the groundstate binding energy increases by 92 meV as R decreases from infinity (equivalent to a straight nanowire) to 1.5 nm.

Our results show that the groundstate binding energy of a 90-degree bent quantum-wire increases by approximately 40 meV as the radius-of-curvature decreases from 20 nm to 2 nm. The value of the binding energy due to quantum-wire bending is thus significant (compared to the exciton binding in a straight wire) and will lead to important changes in, e.g., photoluminescence spectra with varying degree of quantum-wire bending. In fact, the quantum-wire bending leads to spatial confinement of single-particle electron- and hole groundstates at the bent section. This, in turn, leads to an enhanced groundstate exciton binding energy due to the small electron-hole distance (as a consequence of localized electron- and hole groundstates) and the attractive Coulomb interaction.

The present results have been tested vs. Finite Element Method calculations. We find good agreement between results obtained with the differential-geometry and FEM approaches. The computational much faster method proposed in this work is thus convenient for discussing shape effects and electron interactions in quantum structures.

NanoSYD24

Related papers

[1] J. Gravesen, M. Willatzen, and L.C. Lew Yan Voon, “Schrödinger problems for surfaces of revolution - the finite cylinder as a test example,” Journal of Mathematical Physics, 46, 012107 (2005)

[2] J. Gravesen and M. Willatzen, “”Eigenstates of Möbius nanostructures including curvature effects,” Physical Review A 72, 032108 (2005); also published in October 3, 2005 issue of Virtual Journal of Nanoscale Science & Technology

[3] B. Lassen and M. Willatzen, “Geometry-Induced Localization Phenomena in Semiconductor Quantum-Dot Heterostructures,” Physica E, Vol 28/4, 568-575 (2005)

ANNUAL REPORT 2008

We plan to extend the quasi-analytical shape analysis to other problems in nanotructures. Initial studies are presently carried out to address surface plasmon polariton propagation along metal-dielectric interfaces.

25

Benny Lassen

Spurious Solutions in k∙p theoryOne of the main areas of research within the mathematical group is electronic band structure theory for semiconductor nanostructures. The electronic band structure is of interest because it is the basis for predicting properties such as optics and transport. For example, in the QUEST project information about the band structure of quantum dot systems is used to determine the slow down factor for light (the reduction in the speed of light due to the interaction between electromagnetic waves and the nanostructure). There are many different approaches for the determination of the band structure. For the QUEST project multiband k∙p theory is used. This is an empirical approach where the atomistic structure has in a sense been averaged out. However, for some materials this procedure gives rise to non-physical spurious solutions. The mathematical modelling group has been working on the removal of these spurious solutions for some time.

The origin of the spurious solutions that appear in eight band k · p theory for semiconductor nanostructures can be traced back to the root of the approach, which is a perturbation expansion in Fourier space around some k point (usually the α point, i.e., k=0). This entails that the theory is only valid around that point. In Figure 1, we show the conduction and valence bulk dispersion curves along the [111]-direction found using eight band k · p theory and the more accurate atomistic tight-binding approach. We see that the two models are in agreement for small k values, however, for larger values they deviate from each other.

NanoSYD

Plots showing the conduction and valence bands of InAs along the [111]-direction. The solid black lines are tight-binding results and the dashed blue lines are k • p results. a is the lattice constant of InAs.

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Related papers

ANNUAL REPORT 2008

[1] B. Lassen, D. Barettin, and M. Willatzen. To appear in proceedings of the 29th International Conference on the Physics of Semiconductors, 2008

[2] B. Lassen, R.V.N. Melnik and M.Willatzen, Spurious Solutions in the Multiband Effective Mass Theory Applied to Low Dimensional Nanostructures, Comm. in Comp. Phys., Submitted, also available as preprint of the Newton Institute for Mathematical Sciences, NI09006-HOP

This behavior is expected and for the bulk case it is not an issue. However, when we use the eight-band k∙p theory for a heterostructure the large k components will interfere with the solutions we are seeking, so the influence from these components needs to be removed. There are many ways of doing this. Our most recent work focus on the two most common approaches. The plane wave cut-off approach where the problem is solved in Fourier spaces where the large k components can be disregarded and the approach where the material fitting parameters are changed so as to insure that bulk energies for large k components have energies far away from the conduction and valence bands (see [1] for details).

It turns out that the second approach, where the material parameters are changed, is closely connected to whether or not the set of eight coupled partial differential equations making up the model is of elliptical type. This research direction has not been fully investigated yet and it is hoped that this may yield new insights.

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Morten Madsen & Roana Melina de OliveiraMicro- and nano-structured gold surfaces for integrated nanofiber growth

Organic crystalline nanofibers exhibit a wide range of optical properties with potential applications in future submicron-sized opto-electronics and photonics [1, 2]. Para-hexaphenylene (p6P) nanofibers are typically grown by physical vapour deposition of p6P molecules onto a heated muscovite mica substrate in a high vacuum environment, which leads to an array of mutually parallel nanofibers. However, technological applications call for the use of different substrates which allow for further processing. We have been investigating growth of p6P nanofibers on nano- and micro-structured gold surfaces, as a method for achieving in-situ growth of nanofibers on pre-fabricated device substrates. The micro-structures were patterned by photolithography and reactive ion etching in silicon (100). Afterwards a thin gold layer was deposited on the substrate. The nano-structures were made by electron-beam lithography on a gold coated silicon substrate followed by metal deposition and lift-off.

Periodic micro-ridges are fabricated in silicon (100) by optical lithography and subsequent reactive ion etching. After etching, the cleaned silicon samples are coated with 55 nm gold in order to realize a micro-structured gold surface. A nominal thickness of 5 nm p6P is deposited by physical vapour deposition of the molecules on the substrates at different temperatures in a high vacuum environment (10-8 mbar). At low substrate temperatures this results in nanofibers which are grown in all directions on the structured gold surface, both on the micro-ridge and at the bottom of the substrate. However, at high substrate temperatures, there is a preferred orientation of the nanofibers, and they start to grow mutually parallel on the micro-ridges. This is demonstrated in figure 1, which shows scanning electron microscopy and fluorescence microscopy images of nanofibers grown on a 5 µm wide gold coated silicon ridge at a substrate temperature of 388 K and 449 K, respectively. It is seen from the images that the orientation of the grown nanofibers is changed from almost random at 388 K to approximately perpendicular to the micron-sized ridge at 449 K.

We have been investigating this effect at different substrate temperatures both for 5 and 10 µm wide gold coated ridges. Figure 2 shows a plot of the standard deviation of the orientation distribution at five different substrate temperatures. The mean value of the orientation distribution is around 90° which is perpendicular to the long ridge axis.

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It is seen from the figure, that the standard deviation of the orientation distribution decrease with an increased substrate temperature, i.e. there is a preferred orientation for the nanofibers grown at a high substrate temperature. It is also seen, that for growth on 10 µm wide Au coated ridges, a higher substrate temperature is needed to get the same degree of ordering as compared to growth on 5 µm wide ridges. The fact that a high substrate temperature or a narrow ridge is needed for oriented growth to take place can be explained by the assumption that oriented growth starts from an edge of a ridge.

This means, that the diffusing molecules need to reach an edge from which the oriented growth starts and therefore, either a long diffusing length (given by the high substrate temperature) or a short diffusion path (narrow ridge) is needed. These findings make it possible to grow oriented organic nanofibers directly on pre-fabricated substrates by controlling parameters such as dimensions of the micro-structures on the substrate and substrate temperature during the nanofiber growth.

Figure 2

Figure 1: Scanning electron microscopy and fluorescence microscopy images of p6P nanofibers grown on a 5 µm wide gold coated ridge at a substrate temperature of 338 K and 449 K.


Figure 3 is a SEM image of the patterned Ti lines after lift-off and p6P deposition (3 nm, 156oC). The pitch in this sample is 8 µm, and the line width is being increased from the lines at left to the right (200 nm-400 nm). The Ti height is 50 nm. We can see that there are few fibers in between the lines, which means that we have a position control.

NanoSYD

For the fabrication of nanostructures, parallel lines are patterned on 100 nm resist (PMMA A4) by electron-beam lithography. After development, the samples are coated with Ti and submitted to a lift-off process. Plasma cleaning treatment is done and followed by p6P deposition. We want to study the influence of various parameters in our structures on the nanofiber growth, and its influence on the fibers orientation and position. The following parameters were changed in the different samples: line width (70 nm-350 nm), pitch distance (2.5 µm-17.5 µm), p6P thickness (2 nm-5 nm), substrate temperature (125oC-140oC) and Ti line height (15-50 nm). SEM images of the patterned nano-structures were made to analyse the nanofibers growth direction and position. The parameters influence could be estimated and some of our conclusions are:

• Line width: if we have low Ti lines (around 15 nm), the Ti width becomes important, since the fibers only tend to grow from the low lines when the line width is large enough (around 200 nm).

• Pitch distance: If the lines are close, there are almost no fibers in between the lines, and we have good position control. We have observed a better alignment of the fibers when the pitch distance is around 8-10 µm.

• p6P thickness: the fibers length is proportional to the p6P thickness. If the p6P thickness is increased in a substrate with low Ti lines, the fibers are not controlled by the structures, and grow over the lines. Increasing the Ti lines height, the p6P thickness can be increased.

• Deposition temperature: there is a better alignment (the fibers grow perpendicular to the lines) when the temperature is increased. The fibers are also longer when the temperature is increased up to 450 K.

• Ti lines height: the Ti height is influencing the position control of the fibers even at long pitch distances. At high Ti lines (80 nm), all the fibers grow from the lines, independent of the line width, as can be seen in Figure 3.

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Related papers

Experimental results show that oriented growth of nanofibers on micro-structures is not limited to ridges alone. In fact, it is possible to grow nanofibers in microfluidic channels perpendicular oriented to the long axis of the channel, i.e. it is possible to combine in-situ growth of organic nanofibers with microfluidic applications. However, several parameters such as ridge height (or channel depth), p6P thickness and different micro-structure configurations still need to be investigated in order to achieve a further control of the oriented growth of organic nanofibers on micro-structured gold surfaces.

Concerning the fabrication of the nano-structures, more parameters will be changed to achieve the optimized pattern for position and direction growth-control of p6P nanofibers. This optimized pattern will be fabricated using nanoimprint lithography (NIL), since this technique is useful for large scale implementation. In addition, the growth of amino-functionalized nanofibers on the patterned substrate should be investigated- first on the 100 µm by 100 µm substrate patterned by EBL and later on the larger substrates made with NIL.

[1] K. Al-Shamery, H.-G. Rubahn, H. Sitter, Ed´s, “New organic nanostructures for next generation devices”, Springer Series “Material Science”, Berlin (2008)

[2] M. Madsen, G. Kartopu, N. L. Andersen, M. Es-Souni and H.-G. Rubahn, Appl. Phys. A, accepted for publication

[3] M. Madsen, J. Kjelstrup-Hansen and H.-G. Rubahn, Nanotechnology, accepted fot publication

ANNUAL REPORT 2008

Figure 3

31

Manuela SchiekFunctional Nanofibers from customized Organic Semiconductors

General introduction (max 10 lines): Nanofibers, nanowires and nanotubes established their reputation in basic and applied research within the field of nanotechnology. Organic compounds are interesting can-didates because of their structural flexibility and suitability for controlled bottom-up growth. Especially rod-like organic semiconductors such as (functionalized) para-phenylenes, alpha-thiophenes and their cooligomers form mutually well aligned lying nanofibers on an appropriate growth substrate. Controlled growth of upright standing nanofibers is also possible by solution assisted wetting of porous alumina tem-plates. This has so far only been demonstrated for non-carbon based semiconductors. In this project we investigate the possibilities of template assisted growth of upright oriented hydrocarbon semiconductor nanostructures.

A novel organic semiconductor has been implemented for the nanofiber growth. The 2,7-Diphenyl-(9H)-carbazole has been provided by Ivonne Wallmann, University of Bonn (group Arne Lützen), within the scope of a joint PhD-project. Two approaches have been studied for the nanofibers growth: (1) vapour deposition in high vacuum onto a freshly cleaved muscovite mica substrate and (2) solution assisted wet-ting of a porous alumina template.

Figure 1: (a) AFM-image (40 x 40 µm², height scale 180 nm) shows lying nanofibers from 2,7-Diphenyl-(9H)-carbazole (see structural formula top right), whereas (b) shows a SEM-image of upright standing nano-

fibers from the same compound.

In case of vapour deposition onto the mica substrate lying nanofibers are formed, which are built by lying molecules. The nanofibers are mutually aligned, displaying heights and widths of a few hundred nanometers and lengths up to 20 micrometers. Fig. 1 (a) shows an image demonstrating typical carba-zole nanofibers on muscovite mica. It is taken from the Bachelor Thesis of Aghiad Ghazal, University of Southern Denmark, Sønderborg. The nanofibers emit blue, polarized fluorescence light after excitation with UV-light. Their dimensions and mutual alignment are controlled by process parameters like sub-strate temperature and deposition rate. NanoSYD32

Related papers

The SEM-image, Fig. 1 (b), displays upright standing carbazole nanofibers after liberating from the com-mercial alumina growth template. The fiber dimensions are given by the pore sizes, which are here 200 nm in width and 16 micrometer in length. They are grown by a solution assisted wetting process that usually results in the formation of nanotubes instead of nanofibers [1]. These nanofiber samples stem from Kirill Bordo, who recently started his PhD at the University of Southern Denmark, Sønderborg.

For one thing the nanofiber’s remarkable optical properties are due to their high crystallinty, for another thing the growth on ordered substrates is more or less controlled by epitaxy. Therefore knowing the nano-fiber crystal structure as well as the organic semiconductor bulk crystal structure is crucial for understand-ing the nanofiber properties and the growth process, respectively.

Two independent approaches for achieving crystal structures have been realized successfully in coopera-tion projects: (1) Single crystals have been grown by physical vapour deposition from a functionalized p-quaterpheylene, and the crystal structure was determined by x-ray crystallography (Jaroslaw Iwicki, group Lutz Kipp, University of Kiel) [2]. (2) Two-dimensional powders and nanofibers on surfaces from functionalized p-quaterphenylenes have been analyzed with grazing incidence x-ray diffraction (Armin Moser, group Roland Resel, Technical University of Graz) [3].

In order to achieve control over the dimensions of upright standing nanofibers custom-made alumina templates will be used. The nanofiber properties can be adjusted by implementing different, customized organic semiconductors. Crystal structure analysis will be implemented to achieve deeper understanding of growth mechanisms and structure-property-relationships for the nanofibers.

[1] S. Myninhan, D. Iacopino, D. O`Carroll, P. Lovera, G. Redmond, Chem. Mater. 20 (2008) 996 – 1003.

[2] J. Iwicki, C. Näther, M. Schiek, A- Lützen, H.-G. Rubahn, K. Rossnagel, L. Kipp, Crystal structure of 1,4´´´-dimethoxy-4,1´:4´,1´´:4´´,1´´´-quaterphenylene, in preparation 2008.

[3] (a) Armin Moser, Diploma-Thesis: Crystal structure determination from two-dimensional powders - Studies on rodlike conjugated molecules, 2008. (b) A. Moser, O. Werzer, H.-G. Flesch, M. Koini, D.-M. Smilgies, D. Nabok, P. Puschnig, C. Ambrosch-Draxl, M. Schiek, H.-G. Rubahn, R. Resel, Crystal structure determination from two-dimensional powders: a combined experimental and theoretical approach – The example p-cyano-quaterphenylene, Proceedings SXNS 10, Paris July 2008.


Education

Educational Networks

An overwiev of the educational networks NanoSYD is involved in is given in the following figure:

MESO PhD schoolAalborg, Germany

European Doctorate in Physics and Chemistry of Materials

Italy, Spain, Germany, Ireland, Poland, Lithuania

ESGI

Biophotonics network, DOPS Erasmus student exchange

Lithuania, Poland, Germany,Spain, Turkey

Master in

Smart MaterialsFH Kiel

Educational Activities

NanoSYD is involved in nano- and microtechnology education via courses in clean room microfabrica-tion, nanoelectronics, nanostructure characterization and individual study activities. NanoSYD also par-ticipates in Ph.D. education via the Ph.D. school ‘Mesoscopic structures, optics and dynamics’, MESO, and the corresponding courses on interface optics, advanced spectroscopy, surface science, and lasers.

Master in mechatronics, specialization in

nanotechnology FH Flensburg

National International

NanoSYD

www.pcam-network.eu

www.dops.dk

34

www.meso.sdu.dk

Activities

ANNUAL REPORT 2008

11.04. Nanobaserede Sensorer 2 Odense

23.05. Inspirationsdag for naturvidenskabslærere Sønderborg

13.06. On the fantastic properties of nanostructured gold Professor Dr. Katharina Al-Shamery, Sønderborg

14-16.07. 2nd German-Danish meeting on Interface Related Phenomena Sønderborg

10.11. Matchmaking Workshop between SDU and Christian-Albrechts University Kiel Sønderborg

02.12. Nanobaserede Sensorer 3 Sønderborg

18.12. Official Opening of the clean room Sønderborg

18.12 Mini Symposium: Nano at SDU Sønderborg

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Nanoseminars

12.02. Integration and application of nanomaterials and highly miniaturized components Professor Heiko O. Jacobs: Patterning, ECE, University of Minnesota

14.02. Organic Nanowires: New Components for Nanoscale Photonics and Electronics Dr. Gareth Redmond, Tyndall National Institute, Lee Maltings, Prospect Row, Cork, Ireland

06.03. Optical atom manipulation Tomasz Kawalec, Mads Clausen Institute, University of Southern Denmark

27.03. Atomically controlled growth methods of ultra thin films on Si surfaces studied with photoemission techniques, including the use of synchrotron radiation Per Morgen, Department of Physics and Chemistry, University of Southern Denmark

10.04. Sub-wavelength transmission through slits and holes John Weiner, University of Toulouse, Frankrig

24.04. Analysis of gen-modified food Helmut Erdmann, Flensburg University of Applied Sciences, Germany

08.05. Gate controlled tunnelling induced spin-reversal in a carbon nanotube Kondo dot with ferromagnetic contacts Jonas Rahlf Hauptmann, The Niels Bohr Institute and The Nano-Science Center, University of Copenhagen

22.05. The influence of surface corrugations to the epitaxial growth of rod-like conju gated molcules Roland Resel, Institute of Solid State Physics, Graz University of Technology, Austria

19.06. Subwavelength control of surface plasmon fields Romain Quidant, The Institute of Photonic Sciences, Barcelona, Spain

20.06. Nanoscale Chemical Analysis using Near-Field Optical Methods Prof. Renato Zenobi, Department of Chemistry and Applied Biosciences, ETH Zurich, Switzerland

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ANNUAL REPORT 2008

11.09. Three-dimensional Strain Distributions due to Anisotropic Effects in InGaAs Semi- conductor Quantum Dots Daniele Barettin, Mads Clausen Institute, University of Southern Denmark

02.10. Nanoantennas Jonas Beermann, Institute of Sensors, Signals and Electrotechnics (SENSE), University of Southern Denmark, Niels Bohrs Allé 1, DK-5230 Odense M, Denmark

09.10. Integration of self-organized nanostructures into microchip based devices Rainer Adelung

23.10. Enhanced Slow Light Torben Roland Nielsen

06.11. Growth and electronic band structure of organic nano-structures Michael Ramsey, Institute of Physics: Surface and Interface Physics, Karl-Franzens University Graz, Austria

16.12. Organic Monolayers, Networks, Electrochemistry: A Toolbox for the Nanoscale? Manfred Buck, EaStChem School of Chemistry, St Andrews University, North Haugh, St Andrews, KY16 9ST, UK

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Peer-reviewed articles

Organic molecular nanotechnology, SMALL, 4(2008)176; also in NANOWERK, 01.02.2008

M.Schiek, F. Balzer, J. Brewer, K.Al-Shamery and H.-G.Rubahn

Light emitting organic nanoaggregates from function-alised p-quaterphenylenes, Soft matter, 4(2008)277

M.Schiek, F.Balzer, K.Al-Shamery, A. Luetzen, and H.-G. Rubahn

Nanofiber growth on Au-coated porous alumina tem-plates, Appl.Phys.A, accepted (2008)

M.Madsen, G.Kartopu, N.L.Andersen, M.Es-Souni and H.-G.Rubahn

Light scattering from an ordered array of needle-shaped organic nanoaggregates: Evidence for optical mode launching, J.Fiutowski, V.G. Bordo, L. Jozefowski, App.Phys.Lett., 92(2008)073302

M. Madsen and H.-G. Rubahn

From clusters to fibers: parameters for discon-tinuous p-6P thin film growth, J. Chem. Phys., 128(2008)084709

L. Kankate, F. Balzer,H. Niehus and H.-G. Rubahn

Surface Bound Organic Nanowires, J.Vac.Sci.Tec., 26(2008)1619

F. Balzer, M.Schiek, K. Al-Shamery, A Luetzen and H.-G. Rubahn

First order optical nonlinearities for organic nanofibers from functionalized para-phenylenes, Opt. Comm., accepted 281(2008)3892

J. Brewer, M. Schiek, I. Wallmann and H.-G. Rubahn

On the suitability of carbon nanotube forests as non-stick surfaces for nanomanipulation, Soft Matter 4(2008)392

Kjetil Gjerde, R. T. Rajendra Kumar, Karin Nord-strøm Andersen, Jakob Kjelstrup-Hansen, Ken B. K. Teo, William I. Milne, Christer Persson, Kristian Mølhave, Horst-Günther Rubahn, and Peter Bøg-gild

Electronic Properties of Semiconductor Nanowires, J. Nanoscience and Nanotechn, 8, 1-26 (2008)

L. C. Lew Yan Voon, Yong Zhang, B. Lassen, M. Willatzen, Qihua Xiong, and P. C. Eklund

Piezoelectric models for semiconductor quantum dots, to appear in Microelectronics Journal (2008)

B. Lassen, D. Barettin, M. Willatzen, and L. C. Lew Yan Voon

High-Pressure Effect on PbTiO3: An Investigation by Raman and X-Ray Scattering up to 63 GPa, Phys. Rev. Letters 101, 237601 (2008)

P.-E. Janolin, P. Bouvier, J. Kreisel, P. A. Thomas, I. A. Kornev, L. Bellaiche, W. Crichton, M. Hanfland, and B. Dkhil

Publications

NanoSYD38

Phase stability and structural temperature dependence in powdered multiferroic BiFeO3, Phys. Rev. B 78, 134108 (2008)

R. Haumont, Igor A. Kornev, S. Lisenkov, L. Bel-laiche, J. Kreisel, and B. Dkhil

Domains in Ferroelectric Nanostructures from First Principles, Invited review, Book chapter in Advanced Dielectric, Piezoelectric and Ferroelectric Materials - Synthesis, Characterization and Applications, edited by Professor Zuo-Guang Ye, Woodhead Publishing Limited

Igor A. Kornev, B.-K. Lai, I. Naumov, I. Ponoma-reva, H. Fu, and Laurent Bellaiche

Original properties of dipole vortices in zero-dimen-sional ferroelectrics, Invited topical review, J. Phys.: Condens. Matter 20 193201 (2008)

S. Prosandeev, I. Ponomareva, I. Naumov, I. Kornev and L. Bellaiche

Control of vortices by homogeneous fields in asymmetric low-dimensional dipolar systems: A unifying theoreti-cal study of vortices in ferromagnets and ferroelectrics, Physical Review Letters 100, 047201 (2008)Selected for the February 11, 2008 issue of Virtual Journal of Nanoscale Science and Technology

S. Prosandeev, I. Ponomareva, I. Kornev, and L. Bellaiche

Electroxtriction in GaN/AIN heterostructures, Super-lattices and Microstructures, 43, 436 (2008)

M. Willatzen, L. Wang, and L. C. Lew Yan Voon

Modelling of electron states in quantum-wire systems - influence of stochastic effects on the confining potential, Int. J. Mathematics and Mathematical Sciences, 2, 136-142 (2008)

M. Willatzen and M. V. Deryabin

Electronic properties of nanowire superlattices in the presence of strain and magnetic- eld effects, J. Phys. Cond. Matt. 20(34), 345216 (2008)

M. Willatzen and L.C. Lew Yan Voon

Crystal orientation effects on the piezoelectric field of strained zinc-blende quantum-well structures, Phys. Rev. B, 78, 205325 (2008)

L. Duggen, M. Willatzen, and B. Lassen

Surface acoustic wave generation based on GaAs, Tech-nical Acoustics, 19, 1-13 (2008)

D. Bödewadt Carstensen, T. Amby-Christensen, M. Willatzen, and P. V. Santos


ProceedingsBottom-up tailoring of photonic nanofibers, SPIE 6883(2008)

F.Balzer, M.Madsen, R.Frese, M. Schiek, T. Tamu-levicius, S.Tamulevicius and H.-G. Rubahn

Periodic structures modified with silver nanoparticles for novel plasmonic applications, SPIE 6988(2008)

A. Sileikaite, T. Tamulevicius, S. Tamulevicius, M. Andrulevicius, J. Puiso, A. Guobiene, I. Prosycevas, M. Madsen, C. Maibohm and H.-G. Rubahn

Crystal Structure Determination from 2-dimensional Powders - a combined experimental and theoretical ap-proach, EPJ ... (2008)

A. Moser, O. Werzer, H.-G. Flesch, M. Koini, D.-M. Smilgies, D. Nabok, P. Puschnig, M. Schiek, H.-G. Rubahn and R. Resel

Charge-Transport Properties of para-Hexaphenlyene Nanofibers, Proceedings of the 8th IEEE Inter-national Conference on Nanotechnology, 2008, Arlington, Texas, USA (2008)

J. Kjelstrup-Hansen, J.E. Norton, D. A. da Silva Filho, J.-L. Brédas, and H.-G. Rubahn

Plasmonic effects in dynamic tunable metal-dielectric composites, PIERS 2008 Session Title: Scattering by Ordered and Disordered Media: Photonic Applica-tions, July 3-6, Cambridge, USA (2008)

Y. Feng and M. Willatzen

Piezoelectric models for semiconductor quantum dots, W28.00009, Proceedings of the American Physical Society, New Orleans, Louisiana, USA, March 10-14 (2008)

M. Willatzen, B. Lassen, D. Barettin, and L. C. Lew Yan Voon

Cylindrical symmetry and spurious solutions in eight-band k.p theory, Th-PB-004, Proceedings of ICPS 2008, Rio de Janeiro, Brazil July 27 - August 1 (2008)

B. Lassen, D. Barettin, M. Willatzen

Analysis of quantum-dot EIT based on eight-band k.p theory, Th-PB-014, Proceedings of ICPS 2008, Rio de Janeiro, Brazil July 27 - August 1 (2008)

J. Houmark, D. Barettin, B. Lassen, T. Roland Nielsen, J. Mørk, M. Willatzen, and A.-P. Jauho

Exciton states in three-dimensional ring structures - a differential-geometricanalysis, Th-PB-077, Proceed-ings of ICPS 2008, Rio de Janeiro, Brazil July 27 - August 1 (2008)

M. Willatzen and B. Lassen

Nonlinear electromechanical effects in strained GaN-AlN quantum-well heterostructures, Th-PD-032, Proceedings of ICPS 2008, Rio de Janeiro, Brazil July 27 - August 1 (2008)

M. Willatzen, I. Kornev, B. Lassen, and L.C. Lew Yan Voon

NanoSYD40

Testing of a one-dimensional model for Field II calibra-tion, ½ Proceeding of IEEE-UFFC, 4 pages, Bei-jing, November 2-5 (2008)

D. Bæk, J. Arendt Jensen, and M. Willatzen

Three-Dimensional Strain Distributions due to Aniso-tropic Effects in InGaAs Semiconductor Quantum Dots, Talk and abstract presented at the 8th. World Congress on Computational Mechanics (WCCM8) and the 5th. European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2008), Venice, Italy, June 30 - July 4 (2008)

D. Barettin, B. Lassen, M. Willatzen, R.V.N. Mel-nik, and L.C. Lew Yan Voon


BooksNew organic nanostructures for next generation devices, Eds., Springer Series in Materials Science 101, Ber-lin (2008)

K. Al-Shamery, H.-G.Rubahn, H. Sitter

Basics of Nanotechnology, Wiley-VCH (2008) H.-G. Rubahn

Optics and Spectroscopy at Surfaces and Interfaces, Online-Edition, Wiley-VCH (2008)

V.G. Bordo, H.-G. Rubahn

Book articlesOrganic crystalline nanofibers, in ’Design of self-organized morphology in nanostructured materials’, Al-Shamery, Parisi, Ed.s, Springer Series in Materials Science 99(2008)

H.-G. Rubahn

Device-oriented studies on electrical, optical and me-chanical properties of individual organic nanofibers, in ”New organic nanostructures for next generation devices”, K.Al-Shamery, H.-G.Rubahn, H.Sitter, Eds., Springer Series in Materials Science 101, Ber-lin (2008)

J.Kjelstrup-Hansen, P.Boggild, H.H.Henrichsen, J.Brewer and H.-G.Rubahn

Organic nanooptics, in ”New organic nanostructures for next generation devices”, K.Al-Shamery, H.-G.Rubahn, H.Sitter, Eds., Springer Series in Materials Science 101, Berlin (2008)

S.Bozhevolnyi, K.Thilsing-Hansen and H.-G.Rubahn

Device treatment of organic nanofibers: embedding, de-taching and cutting, in ”New organic nanostructures for next generation devices”, K.Al-Shamery, H.-G.Rubahn, H.Sitter, Eds., Springer Series in Materials Science 101, Berlin (2008)

H.Sturm and H.-G.Rubahn

Optical characterization methods of thin films and nanoaggregates, in ”New organic nanostructures for next generation devices”, K.Al-Shamery, H.-G.Rubahn, H.Sitter, Eds., Springer Series in Materials Science 101, Berlin (2008)

H.-G.Rubahn

Domains in Ferroelectric Nanostructures from First Principles, Book chapter in Advanced Dielectric, Piezoelectric and Ferroelectric Materials - Synthesis, Characterization and Applications, edited by Profes-sor Zuo-Guang Ye, Woodhead Publishing Limited (2008)

Igor A. Kornev, B.-K. Lai, I. Naumov, I. Ponoma-reva, H. Fu, and Laurent Bellaiche

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Conference abstractsBottom-up tailoring of photonic nanofibers, SPIE San Jose, Photonics West, MF06 2008

F. Balzer, H.-G. Rubahn

Optical nanosensors based on organic nanofibers - from development to integration, Smart Systems Integra-tion 2008 (2008)

M.Madsen, N.L. Andersen, P.Thomsen and H.-G. Rubahn

On the aspect ratio and packing factor dependence of magnetostatic ineractions in densely-packed Co nanow-ire arrays, DPG Fruehjahrstagung, Berlin (2008)

G. Kartopu, O. Yalcin, A.C.Basaran, M. Madsen, H.-G. Rubahn and M.Es-Souni

Phenyl-thiophene co-oligomer growth on dielectrics, DPG Fruehjahrstagung, Berlin (2008)

F. Balzer, M.Schiek, A.Luetzen and H.-G. Rubahn

Charge-Transport Properties of para-Hexaphenylene Nanofibers, IEEE Nano, Dallas, 14.-18.8. (2008)

J. Kjelstrup-Hansen, H.-G. Rubahn, J.E. Norton, D.A. da Silva Filho and J.-L. Bredas

Imprinted plasmonic surfaces, SPIE Strassbourg 2008 A. Ileikaite, T. Tamulevicius, J. Puio, S. Tamulevi-cius, I. Prosycevas, M. Madsen, C. Maibohm and H.-G. Rubahn

Functionals Nanofibers from Functionalised para-Qua-terphenylenes, ECOSS, Manchester 2008

M. Schiek, I. Wallmann, F. Balzer, T. Kawalec, J. Brewer, A. Luetzen and H.-G. Rubahn

Self assembly of the phenylene-thiophene co-oligomer PPTPP on silicate surfaces: aggregates and wetting lay-ers, ECOSS, Manchester 2008

F. Balzer, M. Schiek, A. Luetzen and H.-G. Rubahn

Growth of oriented organic nanofibers on micro-struc-tured Au surfaces, NTNE, Copenhagen 2008

M. Madsen, R. M. de Oliveira, J. Kjelstrup-Hansen and H.-G. Rubahn

Optical near field studies of waveguiding organic nano-fibers by angular dependent excitation, Palanga 2008

C. Maibohm, T. Kawalec, V.G. Bordo, and H.-G.Rubahn

Determining the crystal structure of organic mol-ecules from 2-dimensional powders, FPi8 Graz 21.-25.7.2008

A. Moser, O. Werzer, H.-G. Flesch, M. Koini, D.-M. Smilgies, D. Nabok, P. Puschnig, M. Schiek, H.-G. Rubahn, R. Resel

Two-photon laser scanning microscopy, 2nd German-Danish meeting on Interface Related Phenomena, Alsion, Sonderborg 2008

C. Maibohm, J. Brewer, and H.-G. Rubahn

Surface structure directed growth of nanomaterials, 2nd German-Danish meeting on Interface Related Phenomena, Alsion, Sonderborg 2008

R. M. de Oliveira, M. Madsen, J. Kjelstrup-Hansen, and H.-G. Rubahn

NanoSYD44

UV-laser induced structure formation for organic materials, 2nd German-Danish meeting on Interface Related Phenomena, Alsion, Sonderborg 2008

R. Frese, M. Madsen, K. Thilsing-Hansen, and H.-G. Rubahn

Light-emitting organic nanoaggregates from functional-ized p-quaterphenylenes and other rod-like molecules with conjugated pi-systems, 2nd German-Danish meeting on Interface Related Phenomena, Alsion, Sonderborg 2008

A. Schäfer, M. Schiek, I. Wallmann, J. Brewer, F. Balzer, A. Lützen, and H.-G. Rubahn

Novel electrode fabrication method for organic nano-fiber light emitting devices, DFS årsmøde, Nyborg, 17.-18.6. 2008

H.H. Henrichsen, J. Kjelstrup-Hansen, H.-G. Rubahn, and P. Bøggild

Templates patterned by electron beam lithography for integrated nanofiber growth, Advanced Materials and Technologies 10, Palanga, 27.-31.8. 2008

R. Oliveira, J. Kjelstrup-Hansen, M. Madsen, and H.-G. Rubahn

Optical near field studies of waveguiding organic nanofibers by angular dependent excitation, Advanced Materials and Technologies 10, Palanga, 27.-31.8. 2008

C. Maibohm, T. Kawalec, V.G. Bordo, and H.-G. Rubahn

Organic nanowires from thiophene-phenylene coo-ligomers, Zing Nanomaterials Conference, Cancun 2008

F. Balzer, M. Schiek, A. Lützen, and H.-G. Rubahn

Functional nanomaterials via molecular nanotechnol-ogy, Zing Nanomaterials Conference, Cancun 2008

F. Balzer, J. Kjelstrup-Hansen, M. Madsen, M. Schiek, K. Thilsing-Hansen, and H.-G. Rubahn

Computational modeling of multifunctional materials, SIAM Conference on Mathematical Aspects of Ma-terials Science (MS08), May 11-14, Philadelphia, PA, USA (2008)

Igor A. Kornev, S. Lisenkov, R. Haumont, B. Dkhil and L. Bellaiche

Finite-temperature properties of multiferroic BiFeO3 from first principles, 2008 Workshop on Funda-mental Physics of Ferroelectrics; Williamsburg, VA, February, 10-13 (2008)

Igor A. Kornev, S. Lisenkov, R. Haumont, B. Dkhil and L. Bellaiche

Finite-temperature properties of multiferroic BiFeO3 from first principles, Extended abstract, 2008 Work-shop Fundamental Physics of Ferroelectrics, Wil-liamsburg, VA, (2008)

Igor A. Kornev, S. Lisenkov, R. Haumont, B. Dkhil, and L. Bellaiche

Properties of Ferroelectric Nanostructures, 2008 APS March Meeting; New Orleans, Louisiana, March 10-14 (2008)

Inna Ponomareva, L. Bellaiche, I. Kornev, B.-K. Lai, I. I. Naumov, R. Resta, and S. Prosandeev


Control of vortices by homogeneous fields in asymmetric ferroelectric and ferromagnetic rings: An unifying theo-retical approach, Presentation at the 2008 Workshop on Fundamental Physics of Ferroelectrics; Williams-burg, Virginia, February, 10-13 (2008)

S. Prosandeev, I. Ponomareva, I. Kornev, and L. Bel-laiche

Properties of ferroelectrics, ferromagnetics, and multi-ferroics from atomistic simulations, Presentation at the 2008 Workshop on Fundamental Physics of Fer-roelectrics; Williamsburg, Virginia, February, 10-13 (2008)

L. Bellaiche, S. Bin-Omran, I. Kornev, S. Lisen-kov, L. Louis, I. Ponomareva, S. Prosandeev, R. Haumont, G. Geneste, B. Dkhil, T. Ostapchuk, J. Hlinka, and J. Petzelt

ThesisManipulation of the Light-Emission of Organic Nano-fibers by Structure FormationHand-in date: June 2, 2008

R. N. Frese

NanoSYD46

Presentations

10.01. Beijing, China, DGF-meeting (Functional nanomaterials via or-ganic molecular nanotechnology)

H.-G. Rubahn

14.01. Xian, China, Northwestern Polytechnical University (Nanotechnol-ogyat MCI)

H.-G. Rubahn

23.01. San Jose, California, USA, Photonics West 2008 (Bottom-up tailor-ing of organic nanofibers)

F. Balzer

28.01. Berlin, Germany, Humboldt University (Fourier optics) F. Balzer

30.01. Oldenburg, Germany, University (Nanofibers for organic solarcells)

H.-G. Rubahn

31.01. Flensburg, Germany, University of Applied Sciences (Nanotech-nologie:Forschung und Entwicklung an der Grenze)

H.-G. Rubahn

04.02. Sønderborg, Denmark, MCI, Alsion, Antibiotics mode (Cleanroom technology at Alsion)

H.-G. Rubahn

07./08.02. Linz, Austria (Organic Solar Cells) F. Balzer

07.02. Linz, Austria, LIOS (Nanofibers for organic solar cells) H.-G. Rubahn

25.02. Sønderborg, Denmark, MCI, Alsion, Dansk industri meeting (Nanotechnology in daily life)

H.-G. Rubahn

27.02. Barcelona, Spain, Photonics Institute (Nanophotonics with active organic nanoaggregates)

H.-G. Rubahn

10.03. Sønderborg, Denmark, MCI, Alsion, visit of sports medicinists (Nano- andmicrotechnologies)

H.-G. Rubahn

02.04. Sønderborg, Denmark, MCI, Meso seminar (Controlled growth of organic nanofibers on micro-structured Au)

M. Madsen

02.04. Sønderborg, Denmark, MCI, Nanoseminar (Raman spectroscopy) C. Maibohm

07.04. Sønderborg, Denmark, MCI, Alsion, visit of Flensburg Lions Club (Nanotechnology)

F. Balzer

NanoSYD48

ANNUAL REPORT 2008

09./10.04. Barcelona, Spain, SSI conference (Optical nanosensors based on organic nanofibers)

M. Madsen, N. L. Andersen, P. Thom-sen, H.-G. Rubahn

10.04. Sønderborg, Denmark, MCI, Alsion (NanoSYD – cleanroom and nanotech initiative)

J. Kjelstrup-Hansen

16.04. Sønderborg, Denmark, MCI, Alsion, M/P landsmode (Micro- and nanotechnologies at SDU)

H.-G. Rubahn

17.04. Sænderborg, Denmark, MCI, Alsion, talk for ITPD-group (Nano-fibers)

C. Maibohm

12./14.05. Siena, Italy, MESO workshop (Template assisted growth of organic nanoaggregates)

M. Madsen

13.05. Siena, Italy, MESO workshop (Nano and nanoproducts at SDU) H.-G. Rubahn

13.05. Siena, Italy, MESO workshop (Micro- and Nanofabrication at Al-sion)

J. Kjelstrup-Hansen

15.05. Siena, Italy, MESO workshop (Organic Nanowires) F. Balzer

16.05. Sønderborg, Denmark, MCI, Alsion, ‘Europa i graenselandet’ (Nanoteknologipaa NanoSYD)

H.-G. Rubahn

26./30.05. Strasbourg, France, E-MRS spring meeting (Controlled growth of organic nanofibers on micro-structured Au surfaces)

M. Madsen, J. Kjelstrup-Hansen, F. Balzer, H.-G. Rubahn

27.05. Strasbourg, France, E-MRS spring meeting (Organic Nanofibers) F. Balzer

10.06. Oakland, CA, USA, University of Berkeley, Nanoseminar (Physics-based models of dynamic response of piezoceramics)

M. Willatzen

11.06. Sænderborg, Denmark, MCI, Alsion, Presentation for medical biology, Odense (Nanotechnology in Sonderborg)

H.-G. Rubahn

24.06. Copenhagen, Denmark, Octopus Meeting (Templates by imprint technology for integrated nanofiber growth)

R. M. de Oliveira

01.07. Venice, Italy, Minisymposium on Mathematical Modeling and Nu-merical Simulation of Coupled Multiphysics Systems in Nano- and Biotechnologies, WCCM8 ECCOMAS 2008 (Three-Dimension-al Strain Distributions due to Anisotropic Effects in InGaAs Semicon-ductor Quantum Dots)

D. Barettin, B. Las-sen, M. Willatzen, R.V.N. Melnik, L. L. Y. Voon

49

14.07. Sønderborg, 2nd German-Danish Meeting on Interface Re-lated Phenomena (Surface structure directed growth of nanoma-terials)

R. M. de Oliveira

18.07. Kiel, Germany, University of Applied Sciences, NiNA work-shop (Nanostrukturierte organische Schichten: Bottom-up vs. top-down Technologien)

H.-G. Rubahn

27.07. Liverpool, UK, University of Liverpool, ECOSS 25 (Self assem-bly of the phenylene-thiophene co-oligomer PPTPP on sheet silicate surfaces: aggregates and wetting layers)

F. Balzer

29.07. Liverpool, UK, University of Liverpool, ECOSS 25 (Functional Nanofibers from Amino-functionalised para-Quaterphenylenes)

M. Schiek

29.07. Rio de Janeiro, Brazil, ICPS 2008 (Nonlinear electromechanical effects in strained GaN/AlN quantum-well heterostructures)

M. Willatzen, I. Ko-rnev, B. Lassen, L. L. Yan Voon

29.07. Rio de Janeiro, Brazil, ICPS 2008 (Cylindrical symmetry and spurious solutions in 8-band kp theory)

D. Barettin

29.07. Rio de Janeiro, Brazil, ICPS 2008 (Analysis of quantum dot eit based on 8-band kp theory

J. Houmark, D. Baret-tin, B. Lassen, T. R. Nielsen, J. Mørk, M. Willatzen, A.-P. Jauho

05.08. Porto Alegre, Brazil, Universidade Federal do Rio Grande do Sul (Templates by electron-beam lithography for integrated nanofi-ber growth)

R. M. de Oliveira

19.08. Arlington, Texas, USA, IEEE 8th International Conference on Nanotechnology (Charge-Transport Properties of para-Hexaphen-ylene Nanofibers)

J. Kjelstrup-Hansen

27./31.08. Palanga, Lithuania, Advanced Materials and Technologies- Third summer school of the European doctorate in physics and chemistry of advanced materials (Templates patterned by Elec-tron Beam Lithography for integrated nanofiber growth)

R. M. de Oliveira, J. Kjelstrup-Hansen, M. Madsen and H.-G. Rubahn

27./31.08. Palanga, Lithuania, Advanced Materials and Technologies- Third summer school of the European doctorate in physics and chemistry of advanced materials (Integration of Nanocomponents in Microsystems)

J. Kjelstrup-Hansen

NanoSYD50

ANNUAL REPORT 2008

05.09. Sønderborg, Denmark, MCI, Alsion Inspirationsdag for natur-videnskabslærere (Verdens mindste rør – Hvordan kan man anvende nanorør?)

J. Kjelstrup-Hansen

23.09. Sønderborg, Denmark, MCI, Alsion, visit of HTF board (K.Bock) and director and sub-director (Nanomarkers: on the way to products)

H.-G. Rubahn

23.09. Copenhagen, Denmark, Nanotech 2008 (Growth of oriented or-ganic nanofibers on micro-structured gold surfaces)

R. M. de Oliveira

24.09. Tønder amtsgymnasium talk for ITPD-group (Nanoteknologi) C. Maibohm

25.09. SDU Odense, Denmark, visit of FTP forretningsudvalg (Nano-SYD: cleanroom and nanotechnology initiative)

H.-G. Rubahn

02.10. Sønderborg, Denmark, MCI, Alsion, Round Table arrangement (NanoSYD – Cleanroom and nanotechnology initiative)

J. Kjelstrup-Hansen

06.10. Cracow, Poland, Jagiellonian University (Organic molecular nano-technology - progress and perspectives)

H.-G. Rubahn

09.10. Sønderborg, Denmark, MCI, Alsion, visit of RAE systems (Nano-SYD - cleanroom and nanotechnology initiative)

H.-G. Rubahn

24.10. Talk at Statsskolen in Sønderborg; title: PhD education C. Maibohm

05.11. Nordborg, Denmark, Danfoss Universe, Danfoss Creative Break (NanoSYD)

J. Kjelstrup-Hansen

10.11. CAU-SDU matchmaking workshop (Nanophotonics and organicthin films)

H.-G. Rubahn

22.11. Bruxelles, Belgium, COST-ATENS meeting (Mathematical Model-ling activities at the Mads Clausen Institute, University of Southern Denmark)

M. Willatzen

01.12. Berlin, Germany, Humboldt-Universität (Doppelbrechung) F. Balzer

02.12. Sønderborg, MCI, Alsion, Nanobased Sensors 3 (Self assembly of PPTPP on mica: aggregates and wetting layers)

F. Balzer

07.12. Cancun,Mexico, Nanomaterials Conference (Organic molecularnanotechnology)

H.-G. Rubahn

51

HOW TO FIND USBy plane:

- Copenhagen and then an internal flight directly to Sønderborg.- Hamburg/Lubeck, then by train to Flensburg and by bus or taxi to Søndeborg.

By train:

- Hamburg, then by train to Flensburg and by bus or taxi to Søndeborg.

NanoSYD52

Documents

Nanosyd Annual Report 2008