New prospects in short wavelength New prospects in short wavelength materials science and spectroscopy materials science and spectroscopy

using various EUV sources using various EUV sources

Nobuhiko. SarukuraNobuhiko. Sarukura

sarukurasarukura--n@ile.osakan@ile.osaka--u.ac.jpu.ac.jpInstitute of Laser Engineering, Osaka UniversityInstitute of Laser Engineering, Osaka University

JapanJapan

Motivation

100 W EUV light source should have some other applications?

Even 1 W EUV would be nice for spectroscopy of wide-gap material

EUV material science

History of LED material

Actual Devices ＩＩＩ－Ｖ compound semiconductors １９７０s

～presentＩＩ－ＶＩ

１９９０s

Nitrides ＩＩＩ－Ｖ compound semiconductors

１９９５～present

Research stage of OxidesZnO １９９５～

Only Fluorides are not explored deeply.

Lots of new complex fluorides

CRC Handbook for laser science and technology

5

Large CaF2 Single CrystalBy CZ method

6

BaLiF3 development status

φ75mm φ100mm φ120mm

Fukuda X’tal Laboratory (FXL) <Transmittance @193nm> Achieved over 97%/cm (internal)

Fukuda X’tal Laboratory (FXL) <Transmittance @193nm> Achieved over 97%/cm (internal)

Tokuyama CF-10 Dept.<Large diameter>Obtained Φ150mm crystal

Tokuyama CF-10 Dept.<Large diameter>Obtained Φ150mm crystal

Remaining issues,- Laser durability- Homogeneity- Reduce SBR

Remaining issues,- Laser durability- Homogeneity- Reduce SBR

Final assessment,- Tokuyama will deliver practicalsamples to lithography customersby 2Q / 2008.

Final assessment,- Tokuyama will deliver practicalsamples to lithography customersby 2Q / 2008.

0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

9 0

1 0 0

1 4 0 1 5 0 1 6 0 1 7 0 1 8 0 1 9 0 2 0 0W a v e le n g th [n m ]

Tran

smitt

ance

[%/c

m]

Absorption coefficient of LiBaF3 and KMgF3compounds in ultraviolet region

121.5126.3

The transmission edges are defined as absorption coefficient of 20 cm-1.

The transmission edges of LiBaF3 and KMgF3 single crystals are 126.3 nm and 121.5 nm, respectively. The measured band gaps of LiBaF3 and KMgF3 are 51 % and 40 % higher than calculated values of 6.51 eV and 7.29 eV.

There is a possibility that complex fluoride optical devises can operate with shorter wavelength than that predicted by ab initio calculation within the LDA.

Perovskite Fluoride Crystals

T. Nishimatsu, et. al., JJAP 41, L 365 (2002)

Some of Perovskite fluoride crystals have direct band gap.

Eg (R)Eg (Γ)

LiSrF3

Direct band gap

Band gap engineering of III-V compound semiconductor

A. Sasaki, et alJJAP, 19, 1695 (1980)

Band gap engineering of III-V compound semiconductor was demonstrated in the 1980s.

Band gap engineering for complex fluoride materials

Control band gap and lattice constant

Let me start with something doable

That will be ZnO and Nd:LaF3

Outline

Hydrothermal method grown ZnO single crystal as fast EUV scintillator for future lithography

Experimental results and DiscussionSummary

Rare-Earth Doped Fluoride Crystals Grown by the Micro – Pulling Down Method as Vacuum Ultraviolet Scintillators

Growth and Characterization ResultsSummary

Collaborators in these works

ZnO Crystal grown by hydrothermal method

Pumped by He-Cd laser at 325 nm

Fluorescence peak 380 nm (3.26 eV)

E. Ohshima, et.al. J. Crystal Growth 260 (2004) 166

Short fluorescence decay time of ~1 ns.Useful emission wavelength (Transparent for glass).Large sized single crystal of up to 3 inch-diameter can be grown.

Hydrothermal method grown ZnO crystal

Sample chambe

r

EUV mirror chamber

EUV generation chamber

EUV laser

Fluorescence

Spectrograph Streak camera

Photograph of Experimental Setup (X-ray laser, JAEA)

3d10

3d94d1Lasing(13.9 nm)3d94p1

A g

Ag19+

(Metal) Heating pulse

(Plasma)Ionization pulse

Solid target (Ag)

x-ray laser

Excitation laser

~ps~ns

3d103d104s24p64d105s1

The 13.9 nm x-ray laser is generated with transient collisional excitation scheme.

Collisional excitation

Rapid radiative decay

Ni-like Ag x-ray laser

Tanaka et.al. Opt. Lett. 28 (2003) 1680.

Streak camera

Spectrograph

Oscillator

BBO LBO 3ω

(351 nm)

Ag targets

EUV

ZnOSample

Visible cut filter

(0.2 μm Zr foil)

Pulsecompressor

Pulse stretcherOptical parametric amplifier

Mo/Si multilayerspherical mirror

Nd:glass amplifiers

Pulsecompressor

1053 nm

(13.9 nm)

Experimental setup of UV excitation

Streak images of ZnO emission

Streak image can be achieved by one shot.Tanaka et.al., A.P.L. 91, 231117 (2007)

The fluorescence behavior is similar in both cases.

ZnO crystal promises to be a feasible scintillation material.

Double exponential decay τA = 1 ns, τB = 3 ns

Comparison of EUV and UV excitations

Tanaka et.al., A.P.L. 91, 231117 (2007)

Band-pass filter (390

nm)

Next step; EUV-visible image converter

Band-pass filter (390

nm)CCD

CCD

ZnO

ZnOZone plate

EUV image

EUV image

This work was in part performed by auspice of MEXT project on mono-energetic quantum beam science with PW lasers. The results were achieved under the Facilities Utilization system of Japan Atomic Energy Agency.

ZnO EUV Scintillator Summary

Demonstrated the excellent properties of ZnO as a scintillation material for the EUV region (13.9 nm)

A few nanoseconds response time shorter than a plasma EUV source

The fluorescence behavior of ZnO is similar in both UV and EUV excitation cases.

Tanaka et.al., A.P.L. 91, 231117 (2007)

Background: Nd3+:LaF3 Emission in the VUV

JOSA B 9, 1148 (1992)

Electron beam pumping

App. Phys. Lett. 46, 14 (1985)

Optical pumping

crucible

melt

growing fiber

Experiment: Growth of Nd3+:La(1-x) Bax F(3-x) and Nd3+:LaF3 by Micro- PD Method

•Crystal growth scheme first established at Tohoku University, Japan in 1994.

• Categorized as a shaped crystal growth method.

• Logical continuation of Czochralski method of crystal pulling from the melt.

• Capable of continuous feeding and multi-crystal growth

A. Yoshikawa, et.,al., Opt. Mater. 30, (2007).@ Tohoku Univ.

Feeding of raw materials

Crystal growth by downward pulling

Nd3+: La(1-x) Bax F(3-x) sample

mm

Diameter: 2 mm

mm

Diameter: 2 mm

Nd3+: LaF3 sample

Experiment: Growth of Nd3+:La(1-x) Bax F(3-x) and Nd3+:LaF3 by Micro- PD Method

Cadatal et.al., J.J.A.P. 46, L985 (2007)

120 160 200 240 2800

25

50

75

100

% T

rans

mitt

ance

Wavelength (nm)

(La1-x, Bax )F3-x (x=0.1)

LaF3

BaF2

(La1-x, Bax )F3-x (x=0.1) more transparent in the VUV region and has a shorter wavelength transmission edge

Transmission Edge [nm]

(La1-x, Bax )F3-x(x=0.1)

164 nm

LaF3 190 nm

BaF2 134 nm

Absorption cross section @ 157nm (x10-20 cm2)

(La1-x, Bax )F3-x(x=0.1)

7.4

LaF3 6.86

Experiment: VUV Transmission of La(1-x) Bax F(3-x) and LaF3 hosts

Cadatal et.al., J.J.A.P. 46, L985 (2007)

sample

VUV Spectrometer and Streak Camera System

Streak camera system

Spectrometer and streak camera system specifications

• Spectral range: 100-600 nm• Spectral Resolution: 1 nm• Temporal resolution 2 ps (synchronized

scan), 50 ps (slow scan)

Cadatal et al. JOSA B Vol. 25, No. 7 B27(2008)

Experiment: Streak Camera Image of Nd3+:LaF3 Fluorescence

157-nm excitation

172-nm fluorescence

First VUV streak camera image

Cadatal et al. JOSA B Vol. 25, No. 7 B27(2008)

Nd3+:La(1-x) Bax F(3-x) and Nd3+:LaF3 Emission Spectral Profiles

150 175 200 225 250

Nd3+:LaF3

Nd3+:(La0.9,Ba0.1)F2.9

157 nm excitation

Fluo

resc

ence

Inte

nsity

(arb

. uni

ts)

Wavelength (nm)

Peak λ

[nm] (a) Nd:LaBaF 175

(b) Nd:LaF 172

FWHM Δ λ [nm](a) Nd:LaBaF 12

(b) Nd:LaF 8

Fluor. cross section σf (x 10-21 cm2] (a) Nd:LaBaF ∼1.73

(b) Nd:LaF ∼1.62

Cadatal et.al., J.J.A.P. 46, L985 (2007)

-10 0 10 20 30 40 50 60

0.01

0.1

1

t = 5nsΔF2 laser

= 8.9(1) nsτNd3+:LaF3

= 6.1(6) nsτNd3+:(La0.9Ba0.1F2.9)

Inte

nsity

(arb

. uni

ts)

T ime (ns)

Nd3+:La(1-x) Bax F(3-x) and Nd3+:LaF3 Emission Spectral Profiles

Cadatal et al. JOSA B Vol. 25, No. 7 B27(2008)

Nd3+:LaF3 Two-photon Fluorescence by THG ( 290nm ) excitation

150 fs, 1 KHz Ti:Sapphire Regenerative Amplifier

λ=870 nm

Third HarmonicGeneratorλ=290 nm

Nd3+:LaF3 Two-photon Fluorescence by THG ( 290nm ) excitation

RareRare--Earth Doped Fluoride Crystal Scintillator Earth Doped Fluoride Crystal Scintillator SummarySummary

Nd3+:(La1-x,Bax)F3-x (x = 0.1) and Nd3+:LaF3 crystals are successfully grown using the micro-Pulling Down method.

Optical properties in the vacuum ultraviolet are investigated

First streak camera image of Nd3+:LaF3 fluorescence using a VUV spectrometer and streak camera combination is presented

This work was partially supported by the Ministry of Education, Culture, Sports, Science, and Technology of Japan, Grant-in-Aid for Young Scientists (A), 19686001, 2007. We thank Prof. Tsuguo Fukuda of IMRAM, Tohoku University, for his useful discussions and suggestions.

Collaborators for these worksCollaborators for these works……

Marilou Cadatal,1-3,＊Yusuke Furukawa,3 Young-Seok Seo,3 Shingo Ono,4 Elmer Estacio,3

Hidetoshi Murakami,3 Yasushi Fujimoto,3 Masahiro Nakatsuka,3 Kentaro Fukuda,5,6 Rayko Simura,6 Toshihisa Suyama,5 Akira Yoshikawa,6 and Fumio Saito6

1 Institute for Molecular Science (IMS), Myodaiji, Okazaki, Aichi 444-8585, Japan2 The Graduate University for Advanced Studies, Hayama, Kanagawa 240-0193, Japan3 Institute of Laser Engineering Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan

4 Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi 466-8555, Japan5 Tokuyama Corporation, Shibuya-ku, Tokyo 150-8383, Japan6 Institute of Multidisciplinary Research for Advanced Materials Tohoku University, 2-1-1 Katahira, Aoboa-ku Sendai, 980-8577, Japan

Yusuke Furukawa,1,* Momoko Tanaka,2 Tomoharu Nakazato1, Toshihiro Tatsumi1, Masaharu Nishikino2, Hiroshi Yamatani2, Keisuke Nagashima2, Toyoaki Kimura2, Hidetoshi Murakami1, Shigeki Saito1, Hiroaki Nishimura1, Kunioki Mima1, Yuji Kagamitani3, Dirk Ehrentaut3, and Tsuguo Fukuda3

1Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan 2Advanced Photon Research Center, Japan Atomic Energy Agency, 8-1 Umemidai, Kizugawa, Kyoto 619-0215, Japan3Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan

ZnO EUV Scintillator

RareRare--Earth Doped Fluoride CrystalsEarth Doped Fluoride Crystals