PREFACE
This annual report reviews the research activities of the Laboratory of Advanced
Science and Technology for Industry (LASTI) in the academic year of 2018 which is from
April 2018 to March 2019) including research activities using NewSUBARU light sourceat the SPring-8 site and other research activities of the micro and nanoscale are carriedout energetically at the Center for Advanced Science and Technology (CAST) II.
NewSUBARU facility has a 1.0-1.5 GeV electron storage ring, which provides lightbeams from IR to Soft X-ray regions, and the largest synchrotron light facility operated
by the university in Japan.
The researches which are carried out are the light sources for next generation througha machine R and D, and the industrial applications such as EUVL lithography, LIGA
process, material analysis.
The annual report describes mainly that topics of the NewSUBARU research activitiesof this year including 1) the research and development of gamma ray application at BL1
beamline, 2) the next generation lithography by Extreme UltraViolet (EUV) lithography
at BL3, BL9B, BL9C, and BL10 beamlines, 3) Lithographie, Galvanoformung, andAbformung (LIGA) process technology at BL2 and BL11 beamlines, 4) the chemical
analysis using soft X-ray absorption fine structure at (BL5, BL9A, and BL7 beamlines
and soft X-ray emission spectroscopy at BL5 and BL9A beamlines at soft X-ray energy
region.
Most of our research activities are being conducted in collaboration research works
with industries, research institutes, and other universities, inside and outside Japan.
We will continue to respond to the community’s demand by offering new science andnovel technology.

Takeo Watanabe

Director of Laboratory of
Advanced Science andTechnology for Industry,
University of Hyogoii

Staff of NewSUBARU（（In front of Advanced Research Building）

iii

The Organization ofLaboratory of Advanced Science and Technology for Industry
University of Hyogo
The organization
Director

Steering
Committee

Department ofLight and Particle Science and Technology

Department ofLight Application for Advanced Technology

Advanced Photon System
Beam Physics
Nanostructure Science and Technology
Guest Chair

Nano-science and Technology utilizing
Synchrotron Radiation
Nano-Micro System
Bio-Medical Technology (to be established)
Guest Chair

Staff (FY 2018)
Research and faculty staff
WATANABE Takeo, Professor , Director
MIYAMOTO Shuji, Professor
KANDA Kazuhiro, Professor
UTSUMI Yuichi, Professor
SUZUKI Satoru, Professor
NIIBE Masahito, Associate Professor
SHOJI Yoshihiko, Associate Professor
HARUYAMA Yuichi, Associate Professor
YAMAGUCHI Akinobu, Associate Professor
AMANO Sho, Research Associate
HASHIMOTO Satoshi, Research Associate
HARADA Tetsuo, Research Associate
Specially appointed staff
TERANISHI Nobukazu, Professor

Administrative staff
HAYASHI Masahiko, General Manager
ISHIHARA Yasunori, Manager
KAYAHASHI Hidetoshi, Chief
KUWATA Ayami, NewSUBARU
HASEGAWA Miwa, CASTAKAMATSU Sumiyo, CASTSAKASHITA Yukiko, CAST
KONO Kimi, CASTMITOME Naruhito, CASTSENBA Ayako, CAST
KUSUMOTO Kumi, CAST
Coordinator
FUKADA Noboru, NewSUBARUFUKUOKA Takao, CAST
Guest staff
MOCHIZUKI Takayasu, Professor
FUKUSHIMA Sei, Professor
OHKUMA Haruo, Professor
ASANO Yoshihiro, Professor
BAN Hiroshi, Professor
KUDOU Hiroto, Professor
WATANABE Yoshio, Professor
HORIBE Hideo, Professor
HARADA Yoshihisa, Professor
NAMAZU Takahiro, Professor
SUGIYAMA Munehiro, Professor
NAGATA Yutaka, Assistant Professor
IKEMOTO Yuka, Assistant Professor
MORIWAKI Taro, Assistant Professor

Contact address
Advanced Research Building
3-1-2 Kouto, Kamigori-cho, Ako-gun, Hyogo, 678-1205 JAPAN.
T:+81-791-58-0249 F:+81-791-58-0242
NewSUBARU Synchrotron Radiation Facility
1-1-2 Kouto, Kamigori-cho, Ako-gun, Hyogo, 678-1205 JAPAN.
T:+81-791-58-2503 F:+81-791-58-2504
Web URL http://www.lasti.u-hyogo.ac.jp/,
http://www.lasti.u-hyogo.ac.jp/NS/
e-Maillasti@lasti.u-hyogo.ac.jp
Accesshttp://www.lasti.u-hyogo.ac.jp/NS-en/access/CONTENTS
PREFACEORGANIZATION of LASTIPart 1. Current Status of NewSUBARU and Other Light Source
NewSUBARU Storage Ring ……………………………………………………………………………
Satoshi HAshimoto (LASTI/University of Hyogo)

1

NewSUBARU Beamlines ……………………………………………………………………………… 4
Masahito Niibe (LASTI/University of Hyogo)

Part 2. Research Activities
Study of laser Compton gamma-ray in side-pumping using laser-diode-array……………………… 12
Sho Amano (LASTI/Univ. Hyogo)
New challenge of GiPS measurement for bulk alloys using LCS gamma beam at NewSUBARU
BL01………………………………………………………………………………………………………
K. Sugita , S. Miyamoto , M. Terasawa , and F. Hori
1

2

2

14

1

(1Osaka Prefecture Univ., 2LASTI/Univ. Hyogo)
XAFS Measurements with atmospheric pressure measurement system in BL05A…………………
T. Hasegawa1, 2, 3

, S. Fukushima

1, 2, 3, and K. Kanda

16

3(1Synchrotron Analysis L.L.C., 2Kobe Material Testing Laboratory Co., Ltd., 3LASTI/Univ.
Hyogo)
Refractive-index changes in SiO2 Films by Undurator Radiation with a multilayer spectrometer… 18
K. Moriwaki1, S.Tanaka1, and K.Kanda2 (1Kobe Univ., 2 LASTI/Univ. Hyogo)
Polymerization of pentacene-related molecules by soft X-ray irradiation…………………………… 20
Akira Heya1, Ryo Yamasaki2, Naoto Matsuo1, and Kazuhiro Kanda3(1Eng./Univ. Hyogo, 2Tocalo Co., Ltd., 3LASTI/Univ. Hyogo)
Production of a high energy beam via backward Compton scattering of soft X-rays from a short
undulator…………………………………………………………………………………………………

v

22

Norihito Muramatsu1, Masahiro Okabe1, Shinsuke Suzuki2, Schin Daté2, Hajime Shimizu1, Haruo
Ohkuma3, Kazuhiro Kanda4, Shuji Miyamoto4, Tetsuo Harada4, Takeo Watanabe4, Manabu
Miyabe1, and Atsushi Tokiyasu1(1Tohoku Univ., 2JASRI/SPring-8, 3Osaka Univ., 4LASTI/Univ. of Hyogo)
Determination of the valence band and Fermi level of organic-inorganic lead halide perovskite
materials by soft X-ray photoelectron spectroscopy…………………………………………………… 24
Naoyuki Shibayama1,2, Yuichi Haruyama3, and Seigo Ito1
(1Eng./Univ. of Hyogo, 2The Univ. of Tokyo, 3LASTI/Univ. of Hyogo)
Evaluation of La doping effect in Sr2IrO4……………………………………………………………… 26
R. Horie1, S. Tsunoda1, Y. Haruyama2, and J. Akimitsu1(1Okayama Univ., 2LASTI/Univ. of Hyogo)
Quasi-free-standing monolayer hexagonal boron nitride on Ni………………………………………

28

Satoru Suzuki1, Yuichi Haruyama1, Masahito Niibe1, Takashi Tokushima1, Akinobu Yamaguchi1,
Yuichi Utsumi1, Atsushi Ito2, Ryo Kadowaki3, Akane Maruta3, and Tadashi Abukawa3(1LASTI/Univ. of Hyogo, 2Eng./Univ. of Hyogo, 3Tohoku Univ.)
Growth and Decomposition of Hexagonal Boron Nitride in the Diffusion and Precipitation Method
Studied by X-ray Photoelectron Spectroscopy…………………………………………………………

32

Satoru Suzuki and Yuichi Haruyama (LASTI/Univ. of Hyogo)
Analysis of chemical reactions at the Au-thin-film/Si interface by soft x-ray photoelectron
spectroscopy under steam ambient……………………………………………………………………… 36
Tomoki Yamamoto1, Satoshi Toyoda2, Satoru Suzuki1, Hirosuke Sumida3, Susumu Mineoi3,
Kazushi Yokoyama1, Akitaka Yoshigoe4, and Shizuka Nishi4(1LASTI/Univ. of Hyogo, 2Tohoku Univ., 3Mazda, 4JAEA)Soft X-ray absorption and Emission Spectroscopy of Monolayer and Few-layer Graphene Sheet… 38
Masahito Niibe1, Satoru Suzuki1, and Shin-ichi Honda2(1LASTI/University of Hyogo, 2Eng./Univ. of Hyogo)
Photopolymer Technology for Extreme Ultraviolet Lithography……………………………………… 41
Takeo Watanabe and Tetsuo Harada(Center for EUV lithography, LASTI/Univ. of Hyogo)
Diffraction Efficiency Measurement of a Transmission Grating for 10-nm EUV Resist
Evaluation………………………………………………………………………………………………… 47vi

Mana Yoshifuji, Shota Niihara, Tetsuo Harada, and Takeo Watanabe(Center for EUV lithography, LASTI/Univ. of Hyogo)
Deterioration Analyses of CFRP Surface………………………………………………………………

51

Hideo Kobayashi1, Yosuke Azuma1, Shogo Suehiro1, Sohta Hamanaka2, Yuki Tobita2, Takuya
Motokawa2, and Yasuji Muramatsu2(1Sumika Chemical Analysis Service, Ltd., 2Eng./Univ. of Hyogo)
Soft X-ray absorption measurements of self-standing polyethylene thin films using a transmission
method……………………………………………………………………………………………………

53

Yuya Matsumoto and Yasuji Muramatsu (Eng./Univ. Hyogo)
Surface structural analysis of nanodiamond by using soft X-ray absorption spectroscopy and the firstprinciple calculations……………………………………………………………………………………

55

Tatsuki Maeda and Yasuji Muramatsu (Eng./Univ. Hyogo)
Direct detection of PM2.5 collected on insulating membrane filters using a total-electron-yield soft
X-ray absorption spectroscopy…………………………………………………………………………

57

Takuya Motokawa and Yasuji Muramatsu (Eng./Univ. Hyogo)
Soft X-ray spectroscopy of coal tars……………………………………………………………………

59

Kosuke Shirai and Yasuji Muramatsu (Eng./Univ. Hyogo)
Controllability of copper particle synthesized by X-ray radiolysis using synchrotron radiation…
Akinobu Yamaguchi1

61, Ikuo Okada , Ikuya Sakurai , Takao Fukuoka , and Yuichi Utsumi
2

2

1

1

(1LASTI/Univ. Hyogo, 2Nagoya Univ.)
Deposition of Polytetrafluoroethylene Film via Synchrotron Radiation……………………………… 63
Masaya Takeuchi, Akinobu Yamaguchi, and Yuichi Utsumi (LASTI/Univ. Hyogo)
Modification of optical property of a Polytetrafluoroethylene by Synchrotron Radiation…………

66

Masaya Takeuchi, Akinobu Yamaguchi, and Yuichi Utsumi (LASTI/Univ. Hyogo)

List of publications(1) Papers ……………………………………………………………………………………………… 70(2) International meetings …………………………………………………………………………… 75(3) Academic degrees ………………………………………………………………………………… 80

vii

Part 1. Current Status of NewSUBARU
and Other Light Source

Staff of NewSUBARU（In front of NewSUBARU Facility）

NewSUBARU storage ring
Satoshi Hashimoto
LASTI, University of Hyogo

1. Introduction
NewSUBARU synchrotron light facility
has a 1.5 GeV electron storage ring, whichis the largest accelerator among
universities in Japan. The general layoutof the ring is shown in Figure 1. The ringis consisted with 6 DBA cells with an inverse
bending magnet with auxiliary coil. There are 6
straight sections between each cell, and they areused for an injection septum, an accelerating RF
cavity, two undulators and a laser Compton
scattering gamma ray source. Electrons are
injected from the linac of SPring-8 through thebeam transport line (L4BT). The main
parameters are listed in Table I.

GeV user time. Night period or weekend is used
for machine study and user time with the special
mode, such as a single bunch operation and achanging the electron energy, if necessary.
Range of the electron energy is from 0.5 GeV up
to 1.48 GeV with 1 MeV step.
The total machine time in FY2018 was 1922
hours, 78.1% of that of FY2017, excluding thebeam down time. Figure 2 shows the breakdownof operation time of the electron storage ring.
The beam down time includes not only thedown by a failure, but also off-beam periods bya beam abort or others due to the beam
instability. The total down time due to themachine trouble in FY2018 was 39hours, 2.0 %of the total operation time.

Table I Main parameters of the NewSUBARU
storage tingCircumference
118.73 m
Lattice
DBA + inv. Bends
Number of bends
12
Radius of curvature
3.217 mRF frequency
499.955 MHz
Harmonic number
198
Betatron tunes
6.29(H), 2.22 (V)Number of IDs
2
Radiation loss per turn33.4 keV (@1.0GeV)
2. Operation Status
The ring has two operation modes foruser-time, 1.0 GeV top-up mode and 1.5 GeV
current decay mode. The basic operation time is
9:00 - 21:00 of weekdays. Monday is used formachine R&D, Tuesday is for 1.5 GeV user
time, Wednesday and Thursday are for 1.0 GeV
top-up user time, Friday is for 1.0 GeV or 1.5

Fig.2 Operation time of NewSUBARU in
FY2018.

Fig.1 General layout of the NewSUBARU storage ring. Electron beams are injected from the 1.0
GeV linac of SPring-8 to the ring through L4BT beam transport line.

1injection at 1.0 GeV. The energy ramping is
executed according to the pre-defined ramping
parameters. However, the reproducibility of
ramping using these parameters is no so good allyear around due to seasonal small changes ofenvironmental temperatures and a ring
circumference. Beam lifetime reduction orstored beam current decrease often occurred
during ramping.
To solve this problem we have used a few
parameter-sets, which properly depend on theseason. Further, to reduce human error andtuning time, we have advanced the automationof ramping process. The first is automatic
generation of the new data set from the standard
data set that is well tuned. The second is theautomatic generation of steering magnet
parameters. The third is real-time betatron tune
correction during energy ramping mentioned in
the next section.
By combining the above three methods, thestability of the energy ramping can be
drastically improved.

3. Machine Trouble
The typical hardware troubles in FY2018
were as follows.
3-1. Instability of the switching power supply
for auxiliary coil of the inverse bending magnet.
This power supply occasionally oscillated at
low operation current. In addition to changing
the deceleration sequence to keep a sufficientcurrent in auxiliary coil even at low energy
operation, the trouble was settled by turning off
a feedback circuit that induces the oscillation in
the power supply.
3-2. Failure of bump magnet power supply.
One of the four bump magnets was failed
due to the broken of the control power supply.
All four control power supplies were replacedwith new ones. And the stored beam current
was reduced several times at the moment ofbeam injection.
This was due to aged
deterioration of thyratron in a power supply forbump magnet No.4. We replaced with spareparts.

4-3. Betatron tune feedback
Betatron tunes drift and fluctuate due tostored current, energy ramping, filling pattern,
ID gap and so on. These also depend on thesmall change of environmental temperatures in ayear and a day.
To solve this problem, we have beendeveloping the real-time tune measurement andfeedback correction system. Development of
this system was completed in FY2018. Using
this system, the averaged injection efficiency
from the linac to the ring could be increased
from 80 to over 90 %. By keeping tunes tooptimized values, the beam lifetime also could
be kept high. This system was developed on
PXI platform. The use of this system during
the user time will start in October 2019.

3-3. RF related issues.
RF synthesizer generating 500 MHz signal
was failed and replaced with the new one. And
some modules consisting the timing circuit were
replaced with the new ones.
3-4. Interlock alarm of power supplies.
Power supplies for quadruple magnet
families often showed “Heat” alarm at start up
time. The automatic startup sequence was often
stopped due to this alarm. We are planning to
update the quadruple power supplies.
4. Machine StudyIn this section, several topics of the machine
R&D are reported.
4-1. SC3 project
Under the collaboration with RIKEN and
University of Hyogo Graduate School ofMaterial Science, we have started SC3 project,
where the generation of the extremely shortradiation pulse corresponding to only a few
wavelengths will be experimentally proved at
NewSUBARU using tapered undulators, amagnetic chicane and a chirped seed laser. The
new ID is under construction and will be
installed in March 2020.

4-4. Automatic ramping operation for
gamma-ray experiments.
The energy of Compton gamma photon canbe continuously changed by changing the stored
electron beam energy.
In search of thedependency on Gamma-ray energy, users had tostop and restart ramping process manually. It
required lots of operational procedures.
We have solved this problem by developing
the automatic ramping operation of the ring for
the Gamma-ray energy dependency experiments.
Using this system, users can start energy
dependency experiments only by clicking abutton. Once an experiment starts, allprocedures such as ramping, measurement and4-2. Stabilization of energy ramping.
The NewSUBARU ting can be operated withstored energy from 0,5 to 1.5 GeV after an2

correction of electron beam orbit, measurement
and correction of betatron tune and Gamma-ray
measurement in BL01 are automaticallyrepeated. This not only reduce operationalcosts, but also improves the reproducibility andaccuracy of energy scans measurements.
5. New Building for Injector
In March 2019 the new building wascompleted adjacent to the existing L4BT

tunnel. This building would be used as a
klystron gallery for the new 1.0 GeV
injector.

Fig.

The new building for klystron gallery.

Acknowledgements

We are greatly thanks to Prof. Shuji Miyamoto of
LASTI for his all activities in our laboratory. The
stable operation of the ring is largely due to Dr.
Yasuyuki Minagawa, Mr. Kazuyuki Kajimoto and Mr.
Yousuke Hamada of JASRI. We also would like tothanks to all the staff of RIKEN and JASRI for theirco-operation in the operation of our facility and theconstruction of the new building for klystrongallery.

3

4

5

6

7

8

9

10

Part 2. Research Activities

M. Takeuchi in a doctor’s course of a graduate school won
the Best Presentation Award in JCK-MEMS/NEMS 2018"11

Study of laser Compton gamma-ray in side-pumping
using laser-diode-array
Sho Amano
LASTI, University of Hyogo

Abstract

We propose a new scheme with a “side-on-collision” between an electron-beam and laser beams
emitted from high-power laser diode arrays in order to obtain high power laser Compton gammaray. To calculate a gamma-ray flux in NewSUBARU, we measured powers, spectra and spatial
characteristics of a typical GaAlAs laser diode array. Using the measured results and the data ofelectron beam at BL01 in NewSUBARU, we calculated a laser gamma-ray luminocity to be 9
photons/mA/W/sec with the “side-on-collision”. This indicates that a laser cavity to enhance
Compton backscattering is required in this scheme. We conclude that the “side-on-collision” schemewith the cavity is expected to generate gamma-ray flux more than10８photons/sec.

Introduction
Based on a concept that more gamma-ray flux
can be achieved by longer interaction length
between electrons and photons, the laser
Compton gamma-ray in “NewSUBARU” isgenerated at a long straight section of a race-track
shaped electron-storage-ring. At present, a
Nd:YVO4 laser emitting at a wavelength of
1.06mm and a CO2 laser at 10.6mm are usedmainly. When each laser irradiated, obtained
gamma-ray luminosity was 6000 photons/mA/W/sec [1] and 7300 photons/mA/W/sec [2],respectively. At both times, a maximum gammaray flux is achieved to be ~107 photons/sec.
The gamma-ray is now used in various
applications but much more gamma-ray flux is
expected. Then, we considered a novel collision
scheme to obtain it. In generally, a “head-on”
collision scheme as shown in Fig.1, where a laser
beam is incident from an opposite direction
toward a relativistic electron beam and collided it(at a point A or B), is used in laser Compton
gamma-ray sources in many facilities. In thisscheme, however, a number of laser source islimited to be only one, then the laser power ofitself has to be increased keeping a good beam
quality in order to achieve higher gamma-ray
power. But this has a limitation. Therefore, in thisstudy, we considered a “side-on” collision asshown in Fig.2, where laser beams are arranged
along an electron beam side, to make a possibilityof gamma-ray power scale-up rule. There are few
examples of studies of laser Compton source withsuch 90-angle collision to generate femto-sec
gamma-ray short pulse [3] or to diagnose electron
beam bunch [4], but we don't know such study as
ours for purpose to achieve higher power.
In this study, we developed a code to calculate
gamma-ray flux. As the lasers for side-on
collision, we considered GaAlAs laser-diode-array (LDA) and measured its power, spectra andbeam characteristics which are required for the
calculation. Using these measured results, we
simulated a laser Compton gamma-ray
generation at the center point of the long straightsection (A) in “NewSUBARU”, operating withelectron storage energy of 1GeV.

Shield tunnel
e

e

A

B

collimator

Shield
hatch

lens

14m

Laser

BL-1

detector

Fig.1 Head-on-collision at NS-BL01 for laser
Compton gamma-ray generation (present status).

Shield tunneleeLaser Diodecollimator

Shield
hatch

lens

14m

BL-1

detector

Fig.2 Side-on-collision at NS-BL01 for laser
Compton gamma-ray generation (proposal).
Equations
Laser Compton gamma-ray flux n (photons/sec)is expressed by Eq. (1).

n

c1

cos 1

U eU l dV(1)Here, Ue, Ul is a spatial distribution of electron andlaser beam, respectively.
Collison cross-section
can be obtained fromdifferential cross-section of Klein-Nishina formula.

12

rk
2 0 2
x1

d
d

2

1
4
x1

1
x2

2

1
2
x1

x1
x2

1
x2

x2
x1

Using the measured results of the LDA, we simulatedside-on collision at the center point of the long straightsection of “NewSUBARU” with the electron energy of
1GeV. As results, it was found that a gamma-ray canbe obtained, which has a photon energy of 11 MeV anda luminocity of 9 photons/mA/W/sec. This luminocity
value is 3 orders smaller than 7000 photons/mA/W/sec
at the present head-on collision. This difference iscaused by the short interaction length between the laser
and the electron beam. Although the interaction lengthis ~10 m in the head-on collision using the long straightsection of “NewSUBARU”, the interaction length is
only ~1 cm of a horizontal diameter of the laser beamin the side-on collision. In conclusion, much gammaray flux cannot be obtained in side-on collision by laser
single-path.
To overcome the demerit of a short interaction lengthin side-on collision, we propose to use a laser cavity
that lengthen an interaction length. This is anapplication of a confocal multi-path cavity [5], which
was proposed before by an author for head-on collisionexperiments. In a case study, when the cavity causes 30
times collisions, an electron current is 300 mA, an
output power of single LDA is 200W (commercial
available) and a number of LDA is 6, a gamma-ray flux
is calculated to be 10 ８ photons/sec that is on orderhigher than a present achieved value in“NewSUBARU”. And the gamma-ray flux can beincreased in proportion to a number of LDA and the
gamma-ray power scale-up rule can be established in
the side-on collision scherm.

(2)

Here,

k2

k1 1
1 k1 Ecos 2 k1 cos
2 k1

x1
x2

cos 1

2 k2

2

1

cos 1

1

cos 2

1

E

(3)

(4)

k1, k2 is a laser and a gamma-ray energy andis a collision and a scattering angle, respectively. r0
is a classical electron radius and is a rest electronenergy. 1 = at a head-on collision and 1 = /2 ata side-on collision. And for backscattering, ２ = 0.
For a calculation of a gamma-ray flux from Eq.(1),
we have to know Ue, Ul . The Ue at the collision pointin “NewSUBARU” has been already known [2] anda unknown value of Ul was measured.

Results & Discussion
We considered to use a compact high-power laser
source of a linear GaAlAs laser-diode-array, which
has an emitting area of 1cm × 1 m. Its output powerand spectral wavelength peak was measured to be
cw20W and 804 nm, respectively. Figure 3 showsemission spatial patterns measured with pin-holescanning method. Fitting both the horizontal andvertical patterns to be gaussian curves, spatial
propagations characteristics were obtained. From theresults, beam wests (horizontal: 6.8 mm, vertical
0.48 m) and M2 factors (horizontal: 1.54, vertical
1.1) of the LDA were obtained and we could
determine Ul.

Acknowledgments
This work was supported by the special study
foundation of University of Hyogo in 2017 (Leading
study A individual).
References[1] K. Horikawa et al., Nucl. Instr. and Meth. A 618,
2010, pp.209-215.
[2] S. Amano et al., Nucl. Instr. and Meth. A 602,
2009, pp.337-341.
[3] Y. Taira et al., Nucl. Instr. and Meth. A 637,
2011, pp.S116-S119.
[4] W. P. Leemans et al., Phys. rev. lett. 77, 1996,
pp.4182 -4185.
[5] S. Amano et al., Jpn. J. App. Phys. 40, 2001,
pp.654-6

500
θv 30
θH 10

400

Power (mW)

V
300
200
H
100

-20000-10000

0

0

10000

20000

Distance from center (µm)

Fig.3 Spatial patterns of the LDA.

13

New challenge of GiPS measurement for bulk alloys using
LCS gamma beam at NewSUBARU BL01
K. SugitaA, S. MiyamotoB, M. TerasawaB, F. HoriA
A: Osaka Prefecture University, B: LASTI, University of Hyogo

Abstract
We have tried a new positron annihilation method by directly implantation the 16.9 MeV Laser
Compton scattering gamma beam into the bulk amorphous alloy. This method is called Gamma-ray
induced Positron annihilation Spectroscopy (GiPS). GiPS can nondestructively measure the bulk
material in the atmosphere. Although the confirmation by the X-ray diffraction of the sample after
annealing was the formation of crystals, the result of GiPS suggests that the crystal and amorphousstat are mixed in the annealing sample. The high energetic GiPS may give us new information aboutbulk materials in addition to the conventional positron annihilation method.
Introduction
Positron annihilation spectroscopy (PAS) is
used as defects research for various materials
such as metallic alloys and semiconductors. In
general, positron searches open space typedefects such as vacancy, void and open volume ina material with non-destructive. Radioisotope(RI) is usually used as a positron source andsometimes used pair-created positrons fromgamma photon. Recently, a new PAS method is
proposed, that is positron production by direct
implantation of a high energetic gamma ray intoa sample and annihilation gamma rays emitted
continuously. In this method, positron source is
not used but high energetic gamma photon
induced positron in a sample is effectively used
for positron annihilation. So far, GiPS hasdeveloped and succeeded at some facilities [1-3].
In this study, we have tried to perform GiPS for
estimation of open volume change in the bulk
amorphous alloys using MeV ordered Laser
Compton scattering (LCS) gamma ray at
NewSUBARU BL01 as a demonstration.

Fig1. Bulk amorphous alloy (left) and crystalized
one by annealing of the amorphous alloy (right).
GiPS setup
Figure 2 shows an illustration of GiPS setup
on the BL01 at NewSUBARU. This apparatus
has consisted of the sample, HP-Ge detector
shielded by Pb block and signal measurement
circuit of an amplifier (ORTEC 671) and amultichannel analyzer (Techno AP). Pb blocks
surrounding the HP-Ge detector has 3 cm
diameter hole faced to a sample as a window ofpassing the positron annihilation gamma. LCS
gamma ray is generated from laser photon andrelativistic electron in a storage ring. The energyof LCS gamma ray can be controlled by the
wavelength of laser light and kinetic energy of anelectron. In this measurement, using awavelength of 1064 nm Nd:YVO4 laser andenergy of 982 MeV circling electron in thestorage ring, 16.9 MeV gamma ray is produced
and implanted it into directly. The implanted
gamma ray is high enough to pass through the
few mm thickness sample.

SampleBulk amorphous alloy of Zr55 Cu30 Ni10 Al5
and crystalized one by annealing were preparedfor positron annihilation measurement as shownin figure 1. The size of these samples is adiameter of 3 cm and a height of 4 cm cylinder
shape. These samples were measured by X-ray
diffraction, positron annihilation Doppler
broadening. For these samples, different open
volume exists in have already reported bymeasuring by using 8 MeV positron beam which
is produced by Hori et al. at the facility [4].

14

Reference[1] M. Butterling et al., Nucl. Inst. and Meth. in
Phys. Research B 269(2011)2623-2629.
[2] Y. Taira et al., Rev. Sci. Instrum. 84,053305(2013).
[3] K. Sugita et al., LASTI Annual Report
vol.19(2017) pp23-24.
[4] F. Hori et al., Jour. of Phys. Conf. Series674(2016)012025.

Fig2. Schematic illustration of the GIPS
measurement system constructed at BL01 in
NewSUBARU.
Measurement
We have measured positron annihilation
Doppler broadening spectra for bulk amorphousand crystal alloy samples by GiPS as mentioned
above. Figure 4 shows the positron annihilation
Doppler spectra in bulk amorphous and crystal
alloys. In this figure, the solid line and the brokenlines are the amorphous alloy and the crystal
alloy, respectively. The peak value of amorphousalloy is slightly higher than that of crystal alloy.
These profiles are analyzed for S-parameter
which is defined as annihilation ratio of thecenter part of the spectra. S-parameter is definedas MCA channel number from 1346 to 1350. Sparameter of the amorphous alloy is larger thanthat of crystal alloy as shown in table 1. This
result shows that the amorphous alloy has avacancy type of open space. This open space inthis alloy corresponds to the free volume inamorphous reported by other positron
measurements [4].

Fig3. Positron annihilation Doppler profiles in
the amorphous alloy and crystallized one.
Table 1. S parameter of the sample.
Sampleamorphous
crystal

S parameter
0.486
0.480

15

XAFS Measurements with atmospheric pressure
measurement system in BL05A
T. Hasegawa1, 2, 3, S. Fukushima1, 2, 3 and K. Kanda3Synchrotron Analysis L.L.C., 2Kobe Material Testing Laboratory Co., Ltd., 3LASTI, University of Hyogo

1

Abstract

BL05A is a double crystal monochromator (DCM) beamline of NewSUBARU for X-ray
absorption fine structure (XAFS) spectroscopy in the soft X-ray region. This beamline isavailable for atmospheric pressure measurements under He gas in a sample chamber withberyllium window. We tried to apply a liquid cell to measure the spectra of real samples andevaluated practical analysis with the cell. The diesel engine oils before and after the carrunning were used as real samples. Consequently, this cell enabled us to measure the spectra forthe chemical states of elements in the oils.

Introduction
X-ray absorption fine structure （ XAFS ）spectroscopy has been applied to analyze thelocal structure and the electronic states of
elements. XAFS measurement is a powerful tool
for analyzing the characterization of materials,
because it can investigate the local structure near
specific atoms. XAFS measurements for the soft
X-ray are most frequently performed undervacuum conditions. Because the energy range ofthis X-ray is harder to pass through the air, but it
can travel in a vacuum efficiently. For thatreason, it is difficult to be adapted formeasurements of liquid sample and wet sample.
But transmission rate of this X-ray become
dramatically better under He gas compared withthe air. Therefore, XAFS measurements underatmospheric pressure in He gas are normally
performed for these samples. We have equipped
BL05A of NewSUBARU with a sample chamber
for atmospheric pressure measurement system
to respond needs for industrial users. In addition,
we succeeded in XAFS measurements of thestandard aqueous solution by making the sealed
cell for containing the liquid. In the next stage ofthe measurements, we tried to apply the liquidcell to the real samples and analyze the elements
including in them. In this paper, we report on the
preliminary research of the liquid samples forpractical analysis of XAFS under atmosphericpressure.

4150 eV. XAFS measurements can be performedin these energy range at the Na-, Mg-, Al-, Si-, P-,
S-, Cl-, K- and Ca-K edges. BL05A is available
for atmospheric pressure measurements underHe gas. A beryllium window with thickness 45
m is used to separate a high vacuum in thebeamline from a He atmosphere in the sample
chamber (Fig.1). This window is brazed
high-vacuum gate valve with the front of thechamber. We have succeeded to make thepolyethylene cell for liquid sample andperformed XAFS measurements of various
aqueous solutions in user analyses. We tried toapply the liquid cell to measure the spectra of thereal samples through the use of diesel engine oils.
The engine oils before and after the car runningwere prepared for the experiments, 0 km and56,260 km running, respectively.

Experiments
BL05A of NewSUBARU, a branch line of
BL05, is a double crystal monochromator(DCM) beamline for XAFS spectroscopy [1, 2,
3]. BL05A is applied five different crystals tocovers the X-ray energy range from 950 eV to

Fig.1 A sample chamber for atmosphericpressure measurement system.

16

These oil samples were injected into thepolyethylene sheet sealed with a heat sealer byusing a plastic syringe and mounted to a holder
with double-sided conductive tape. X-ray
fluorescence (XRF) and XAFS analysis wereattempted to evaluate practical analysis with thecell in BL05A.

[ 104]

a
b
c

1

S

Count（counts）

0.8

Results
The results of XRF spectra of the engine oils
before and after the car running and thepolyethylene sheet used in the cell measured in
atmospheric pressure with He gas are shown in
Fig.2. XRF is measured using SII Vortex silicon
drift detector with 3100 eV incident beam. The
measurement live time for each sample was set
at 100 seconds. XRF spectra is indicated thatseveral elements are present in the oils. Si was
detected both in the oils and in the polyethylene
sheet. On the other hand, P and S detected in theoils weren’t virtually absent in the polyethylene
sheet. The results of S-K edge XANES spectra of
the engine oils before and after the car runningand reference samples measured in atmosphericpressure with He gas are shown in Fig.3. The
spectra of these samples were measured with thepartial fluorescence yield mode by InSb (111)crystal. The oxidation state of organic andinorganic S species is commonly known as theoxidation numbers between -2 and +6. The
spectra show that there are multiple oxidation
states of sulfur in the oils that is higher than theoxidation number in S8. In addition, the peak at
2481.7 eV for S6+ in sulfates of engine oil after
the car running is increased compared to before
one. In this preliminary research, we succeeded
to obtain the spectra for the chemical states ofsulfur in oils and confirmed that this cell isapplicable to practical analysis of XAFS underatmospheric pressure.

0.6

0.4

Si P

0.2

0

1000

2000

Cl
3000

Photon energy（eV）

Fig.2 XRF spectra of the engine oils, (a) 0 km,(b) 56,260 km running and (c) polyethylene
sheet used in the cell.

Intensity（a.u.）

beforeReferences[1] T. Hasegawa et al., Advances in X-ray Chem.
Anal. Jpn., 41, pp.99-106 (2010) [in Japanese].
[2] K. Kanda et al., J. Phys.: Conf. Ser., 425,
132005/1-4 (2013).
[3] T. Hasegawa et al., LASTI Annual Report,
vol.17, pp.16-17 (2015).

after

S8

K2SO 4
2460

2480

2500

Photon energy（eV）

Fig.3 S-K edge XANES spectra of the engine
oils before and after the car running andreference powder samples.

17

Refractive-index changes in SiO2 Films
by Undurator Radiation with a multilayer spectrometer
K. Moriwaki1, S. Tanaka1, and K. Kanda2
Graduate School of Eng., Kobe University, 2LASTI, University of Hyogo

1

Abstract

Undurator radiation (UR) with a multilayer spectrometer by the NewSUBARU (BL7A) is used
for SiO2 modification that can be applied to photonic devices. The measured refractive indices do
not show sharp peaks by varying the UR peak-energy, although it has a slight increase in the lower
peak-energy range. Optical absorbance is measured after the UR radiation, because defects
generated in the SiO2 films may be the main cause of the refractive index changes. Correlation
between the optical absorbance increases and the refractive-index increase is found, while it is aslightly dispersive relation. An island-like morphology is found on the surface for UR irradiatedsamples without spectrometer that suggests nonuniform surface reduction.

Introduction
Synchrotron radiation (SR) and undurator
radiation (UR) can be used especially forradiation-induced material modifications in SiO2
material for optical devices like opticalwaveguides1,2). UR is a very useful tool for thematerial modifications, because it can select a
useful wavelength, and has very high intensity.
By using a multilayer spectrometer, UR becomes
more useful for the device applications, because
the most suitable wavelength without higher
order ones cab be used. The former experiments
revealed various refractive index changes by the
UR radiation with and without a spectrometer1,2).
In this report, refractive-index modification
effects are mainly investigated further, especiallyfor irradiating peak energy dependences and for
depth profiles by etching the samples

that suggest the nonuniform modification layer.
Figure 1 shows surface morphology map of 2x2
m2 area, and a surface profile on the horizontal
line shown in the map. It may mean that the
reduction layer with Si-Si bonds is not uniform
and has islands on the surface. It will be
determined by measuring surface map of Si andO elements in the future.

Fig.1 Surface morphology map (left) of
2x2 m2 area for a sample irradiated by UR
without the spectrometer, and a surface
profile (right) on the horizontal line shownin the map.

Experiments and Results
Thermally grown SiO2 films (0.5 m thickness)on Si substrates and fused quartz substrates wereused for the UR radiation (BL-7A) with andwithout the spectrometer. UR with peak energy
ranging from 80 to 390 eV is used with thespectrometer including the 3rd and the 5th order
peaks. Irradiated samples were characterized byrefractive-index measurements using a reflection
spectrophotometry,
opticalabsorption
spectroscopy and atomic force microscopy(AFM).
Very high refractive index changes after theirradiation by UR without the spectrometer were
found in the sample surface that were mainly by
the surface reduction layer having Si-Si bonds1).
By using UR radiation with the spectrometer, SiSi bonds were not found, so that the refractive
index rises were not as high as those without the
spectrometer1). For those samples with the Si-Si
bonds on the surface, AFM is used to find thesurface morphology. Figure 1 shows the results

Figure 2 shows refractive index changes for anirradiated SiO2 film as a function of the UR peakenergy. The results in Fig. 2 shows relatively flat
dependence on the peak energy, although it has aslight increase in the lower energy range. In thosemeasurements, the refractive index values can be
determined precisely2) (1x10-3 or less) utilizing
the accurate value of thermally grown SiO2-films
thickness (500 nm). The reason of the slightincrease in the lower energy range is not clear yet.
Defects in SiO2 films after UR radiation would
be the main origin for the refractive index
changes. Those defects can be measured by
optical absorption measurements. By measuring
optical absorbance for irradiated quartz
substrates, a correlation between it and the18

1.475

Beforeetchingetching
BeforeRefractiveindex
index
Refractive

1.470

1.465

After
After etchingetching

1.460

1.455

Reference

500

400

300

200

100

Film thickness(nm)Thickness (nm)Fig.4 Refractive index changes in SiO2
films after UR radiation with thespectrometer at a peak energy of 120 eV anda dose of 500 mA h before and afteretching.

0.06

0.08

0.05

0.06

0.04

AbsorbanceAbsorbanceAbsorbanceIntensity(arb.unit)

Fig.2 Refractive index changes at=633nm for SiO2 films after irradiation
by UR with the spectrometer as a functionof peak energy at a dose of 500 mA h.

0.03
0.02

0.04

etching
etching

0.02
0.00

0.01
0.00

Before etching
380nm etching
730nm etching
990nm etching
1460nm etching

-0.02

1.460

1.465

1.470

1.475

1.480

Refractive index

Refractive index

200

250

300

wavelength(nm)
Wavelength
(nm)

350

Fig.5 Optical absorbance for samples
irradiated by UR with the spectrometer (ata peak energy of 120 eV and a dose of 500
mA h) before and after etching 4 times.

Fig.3 Correlation between absorbance andrefractive-index changes for samples after
irradiation by UR with the spectrometer.
Absorbance peaks at a wavelength of 210
nm are used.

refractive index changes by measuring opticalabsorbance before and after etching the quartz
substrates 4 times. Further investigation isnecessary for an application to optical devices

refractive index changes is found as shown in Fig.
3. Although the measured points in Fig. 3 are
distributed around a linear line and are not sosimple, the correlation is clear. It is not clear
whether specific defects cause the refractive
index changes or not.
For optical device applications, depth profile of
the refractive index changes in the irradiatedsamples is extremely important. Figure 4 showsa measured depth profile where refractive indices
are shown for samples before and after etching 3
times. The refractive indices are measured in Fig.
4 after etching the sample by 60 nm, 260nm and
330 nm respectively. The refractive index
decrease is sharp even after the 60nm etching. It
means that the refractive-index change region is
not so deep so that an application to opticaldevices is not so easy, because it usually needs
m-deep changes for the application. Figure 5
shows results that also indicates the shallow

Conclusions
SiO2 films were irradiated by UR with andwithout the spectrometer, and characterized
mainly by their refractive index changes. The
refractive index changes were precisely analyzed
at less than 1x10-3. Refractive index changes as afunction of photon peak energy showed relatively
flat dependence without sharp resonant peaks.
For a mechanism to increase the refractive index,
further investigations are necessary. The authors
thank R.Fujiwara for his help in the experiments.
References[1] K.Moriwaki et al., LASTI Annual Report
vol.18 (2016)43.
[2] K.Moriwaki et al., LASTI Annual Report
vol.19 (2017)33.

19

Polymerization of pentacene-related molecules by soft
X-ray irradiation
Akira Heya1, Ryo Yamasaki2, Naoto Matsuo1, Kazuhiro Kanda3
1

Graduate School of Engineering, University of Hyogo, 2 Tocalo Co., Ltd., 3 LASTI, University of Hyogo

Abstract

We have tried to fabricate graphene nanoribbons (GNRs) from pentacene molecules by soft X-ray irradiation.
The nanocarbon film consisting of pentacene (Pn) and 6,13-dihydropentace (DHP) was prepared by hot meshdeposition (HMD). The nanocarbon film consisting of Pn and DHP was changed by soft X-ray irradiation. The
combination of HMD and soft X-ray irradiation is expected as a novel method for GNR fabrication.

Introduction
The nanographene molecules are attractive
two-dimensional materials consisting of carbon
atoms arranged in a hexagonal lattice. The
graphene nanoribbons (GNRs) have band gaps that
depend on the ribbon width. Therefore, GNRs are
expected to be used in next-generation
semiconductor devices as part of logical elements,
transistors, spin transistors, and gas sensors.
Several fabrication methods for GNR,
including the patterning of graphene sheets bylithography, unzipping carbon nanotubes, andbottom-up processing using a precursor with ahexagonal lattice have been investigated.
We have also investigated the fabrication
method of GNRs using pentacene (Pn), H2 gas andW mesh. This method is named hot meshdeposition (HMD) [1]. The 6,13-dihydropentacene(DHP) was generated from Pn by HMD. In
addition, we discovered that the threshold
temperature for crystallization of inorganic
semiconductor materials (Si, Ge and SiGe films)
was reduced by irradiation of soft X-ray with highphoton flux density generated from synchrotron
facility NewSUBARU [2]. Therefore, thecombination of HMD and soft X-ray irradiation is
expected as novel method for GNR fabrication
method.
In this study, we have tried to fabricate GNRs
from pentacene by using HMD and soft X-ray
irradiation.

elsewhere [1]. The deposition of nanocarbon film
was performed using a pentacene source. A
WNi(3%) mesh was set between the pentacene
source in a Mo boat and a quartz substrate 20×20mm2 in size. The flow rate of H2 and gas pressure
were 400 sccm and 30 Pa, respectively. The
distance between the mesh and the quartz substrate
was fixed at 100 mm. A pentacene source (30 mg)
in a Mo boat was placed in a 26-mm diameter
quartz tube. To vaporize the pentacene molecules,
the Mo boat was heated to 315 C using a coilheater. The deposition time was fixed at 300 s. The
WNi(3%) mesh temperature (Tmesh) was 1450 C.
The irradiation of soft X-rays was carried out
at BL07A of NewSUBARU. The light source of
BL07A was a 2.28 m undulator. The storage-ringenergy was 1 GeV. The beam size measured with afluorescent plate on the sample surface was 7.5 ×
7.5 mm2. The photon energies was 300 eV. The
storage-ring current and dose were 300 mA and
400 mA h, respectively.
The property of nanocarbon film was measured
by laser desorption/ionization mass spectrometry(LDI-MS). The change in molecular structure bysoft X-ray irradiation was evaluated by UV-Vis
absorption spectroscopy and Raman scattering
measurement.
Results and discussion
The LDI-MS spectra of the nanocarbon film
prepared by HMD are shown in Figs. 1(a) and (b).
The intensities from Pn and DHP were notsignificantly different. The Pn molecules likely
came into contact with the heated Ni surface, andsome became DHP at a Tmesh of 1450 C.
Conversely, the pentacene molecules that come incontact with the heated bare W surface did notdecompose. From the Fig. 1(b), pentacene
monomers and pentacene multimers (PMs) weregenerated under the present deposition conditions.
Although the ratio of multimers to monomers was
low as 11%, a nanocarbon film consistingExperimental
A W mesh (10×55 mm2) with a wire diameterof 0.1 mm and 30 holes/inch was used. Ni particles
were supported on the W mesh surface with anatmospheric plasma spray. A mixture of Ar and H2
was used as the plasma generation gas. The plasma
power was 38.5 kW. The Ni was supported on both
faces of the W mesh with supported Ni area ratios
of 3% were prepared.
The HMD apparatus is already shown in

20

primarily of PMs was obtained from the pentacene
source on the quartz substrate without a metal
catalyst. The ratio of Pn : DHP: PMs wasestimated to be approximately 0.5 : 0.4 : 0.1 fromLDI-MS spectrum.
The UV-Vis spectra are shown in Fig. 2. The
amorphous carbon (a-C) film prepared by reactive
heating is also shown as a reference. The peak due
to conjugated double bond was not observed in a-C
film. On the other hand, the absorption peaks due
to conjugated double bonds were observed in the
UV region of both of before and after soft X-ray
irradiation. The absorption peak changed from a
sharp peat at 272 nm to a broad peak over visible
region. The sample color was changed from lightbrown to black as shown in Fig. 2.
The Raman spectra of the nanocarbon film
prepared by HMD before and after soft X-ray
irradiation are shown in Fig. 3. The peaks due to
Pn at 1179 and 1373 cm-1 were not observed
before soft X-ray irradiation. It indicates that themolecular orientation of Pn was disordered byexistence of DHP and PMs. The Raman spectra
drastically changed and the broad peaks attributed
to G and D bands were confirmed after soft X-ray
irradiation. The polymerization reaction could
occur by soft X-ray irradiation. It was consideredthat the decomposition reaction also occurred bysoft X-ray irradiation simultaneously because thepeak due to D band was observed.

Fig. 1. LDI-MS spectra of the nanocarbon
film prepared using the WNi(3%) mesh. (a)Mass numbers from 276 to 284. (b) Mass
numbers from 0 to 1600.

Conclusions
The nanocarbon film with the ratio of Pn :DHP : PMs of 0.5 : 0.4 : 0.1 was obtained by HMD.
Under the present soft X-ray irradiation condition,
the polymerization and decomposition (C and H
desorption) occurred by soft X-ray irradiation
simultaneously. To fabricate the GNRs, it isconsidered that the control of not only molecularorientation and distribution but also optimizationof soft X-ray irradiation are required.

Fig. 2. UV-Vis spectra of the nanocarbon
films prepared by HMD before and after soft
X-ray irradiation. The a-C film is also shown
as a reference. The optical images are also
inserted.

References[1] A. Heya, R. Yamasaki, and N. Matsuo, Thin
Solid Films 675 (2019) 143.
[2] A. Heya, K. Kanda, K. Toko, T. Sadoh, S.
Amano, N. Matsuo, S. Miyamoto, M. Miyao, T.
Mochizuki, Thin Solid Films 534 (2013) 334.

Fig. 3 Raman spectra of the nanocarbon
films prepared by HMD before and after soft
X-ray irradiation.

21

Production of a high energy beam via backward
Compton scattering of soft X-rays from a short undulator
Norihito Muramatsu1, Masahiro Okabe1, Shinsuke Suzuki2, Schin Daté2, Hajime Shimizu1, Haruo Ohkuma3,
Kazuhiro Kanda4, Shuji Miyamoto4, Tetsuo Harada4, Takeo Watanabe4, Manabu Miyabe1, Atsushi Tokiyasu1
1
ELPH, Tohoku University, 2 JASRI/SPring-8, 3 RCNP, Osaka University, 4 LASTI, University of Hyogo

Abstract

A high energy beam up to 0.6 GeV can be produced via backward Compton scattering of 92 eV
X-rays from 1 GeV electrons at NewSUBARU. The soft X-rays will be obtained from the short
undulator at BL07 with the backward reflection using a Mo/Si multi-layer mirror. For this purpose,
a cylindrical mirror base to focus X-rays at the straight section has been prepared. In addition, we
have carried out the installation of vacuum chambers and the development of several detectors for
X-rays and a beam.

Introduction
A laser light is usually injected into theelectron storage ring for the production ofa high energy
beam via backward
Compton scattering. In our project, soft
X-rays of about 92 eV are being injected
instead in order to obtain much higher
energybeam for new generation
experiments of hadron physics. In case of
the 1 GeV operation at NewSUBARU, theenergy spectrum of such abeam iscalculated as shown in Fig.1, where theCompton edge is extended to 585 MeV
compared with 51 MeV by the injection of
355 nm ultraviolet laser.
For the demonstration experiment of
X-ray Compton backscattering, we plan touse a short undulator (total length: 2.28 m,
period length: 7.6 cm) at BL07 as an X-ray
source, and then reflect the radiated
X-rays backwardly into the original
straight section. A Mo/Si multi-layer

mirror will be installed at BL07A for thisreflection. A schematic view of ourexperimental setup is shown in Fig.2.

Figure 1 Energy spectrum of a beam via
backward Compton scattering of 92 eV X-rays
from 1 GeV electrons.

Figure 2 Experimental setup of X-ray Compton scattering at NewSUBARU BL07A.

22

Summary of achievements
In FY2018, we achieved the following
preparation works:(1) The experimental setup was designed
in detail. Accordingly, two vacuum
chambers were newly installed at
BL07A. One chamber will be used to
set the multi-layer mirror on highprecision stages with cooling water
circulation. The other will be used forthe monitor of radiated and reflected
X-rays. A wire scanning detector was
installed to measure their profiles withan increase of micro current.
(2) A base plate for the Mo/Si multi-layer
mirror was developed with a low
thermal expansion glass ceramic(Zerodur). The reflection surface wasformed in a cylindrical shape with acurvature radius of 16.7 m, as a resultof the ray trace simulation by
SHADOW.
(3) For the energy measurement of abeam produced by backward Compton
scattering, a high resolution electromagnetic calorimeter was made byassembling 9 PbWO4 (PWO) crystals,
the individual sizes of which are
20 20 200 mm3. A
beam profile
monitor was also prepared by crossing
1 mm2 scintillating fibers in the area of
50 50 mm2.
Development of an X-ray mirror baseBecause the switching mirror of BL07
possesses a spherical surface, the X-rays
at our reflection mirror chamber are
parallel in the horizontal direction but
divergent for the vertical component. Thisfeature was confirmed by the SHADOW
simulation, as shown in Fig.3. In order tofocus the reflected X-rays at the straightsection of BL07, we need a cylindricalmirror with a curvature radius of 16.7 m,
which corresponds to the distance between
the mirror and the Compton scattering
point. A good focusing behavior was also
confirmed by SHADOW.
Based on this study, we developed acylindrical X-ray mirror base by using a
5 mm-thick and 80 80 mm2 Zerodur plate.
First of all, very thin SUS wires were
sandwiched by two Zerodur plates. In thenext step, the Zerodur plates were bended
by applying a weight of a few tens kg at
the edges, as shown in Fig.4. The
adjustment of their curvature radius wasdone by changing the wire radius and theapplied weight. The bended state was kept
by putting epoxy adhesive between the twoplates, and the outside surfaces weremechanically polished to flat planes with aroughness of several nm. The epoxy
adhesive was removed by heat to release
the bending force. The desired cylindricalmirror surfaces were finally achieved at
outsides. The produced curvature wasconfirmed by measuring a variation of
depth on the mirror surface and counting
the number of Newton fringes with a flat
plate under a Na lamp. The Zerodur plates
have been cut in 50 50 mm2, and they are
ready for the multi-layer coating of Mo/Si.

Figure 3 SHADOW simulation result of the
X-ray positions and slopes at the reflection
mirror chamber in the horizontal (x / x’) andvertical (y / y’) directions.

Figure 4 Method to produce two bended
Zerodur plates with the application of weight.

Acknowledgments
This research was supported in part by
Grant-in-Aid for Challenging Research(Pioneering) No. 18H05325.

References[1] http://www.rcnp.osaka-u.ac.jp/~mura/kaitaku/23

Determination of the valence band and Fermi level oforganic-inorganic lead halide perovskite materials by soft
X-ray photoelectron spectroscopy
1

Naoyuki Shibayama1,2, Yuichi Haruyama1,3, Seigo Ito1
Graduate School of Engineering, University of Hyogo, 2Graduate School of Arts and Sciences,
The University of Tokyo, 3LASTI, University of Hyogo
Abstract

An understanding of the electronic structure of perovskite materials used in solar cells is essential
for their performance improvement. Synchrotron photoelectron spectroscopy was used toexperimentally delineate and energy position of the valence band structure and the Fermi level ofthe perovskite. The valence band of the perovskite was measured using photoelectron spectroscopy
with ultraviolet photoelectron spectroscopy (He 1α line: 21.22 eV) and soft X-rays photon energy(SX-PES: photon energy of 100 eV) and these results were compared. This work is important for
the engineering and optimization of solar cells and their semiconductor properties.

DMSO were prepared by adding separate
materials of PbI2 and MAI with a molar ratio of
1:1. The FTO glass substrates (TEC-15, NSGPilkington) were cleaned ultrasonically withdetergent, distilled water, and ethanol
respectively, and treated with O3 for 15 min toeliminate organic impurities and make thesurface clean. A solution of CH3NH3PbI3 was
spin-coated on the FTO glass with 1000 rpm for
10 sec and with 5,000 rpm for 30 sec,
subsequently, inside a drying room with adewpoint temperature of -30 °C. During the spin
coating, toluene was dripped on the perovskite
layer. The film was annealed at 60 °C for 10 min
and at 100 °C for 15 min, subsequently.
The measurement of SX-PES was
performed using NewSUBARU BL07B.

1. Introduction
In the recent years, perovskite solar cells(PSCs) based on organic-inorganic halide
perovskite absorbers have attracted considerable
attention, due not only to their superb photo
conversion efficiency but also to the low cost of
the source materials. Since the first PSCs with
3.8% were reported by Prof. Miyasaka and coworkers1, the PSCs conversion efficiency hasreached above 24%2,3. This surprising
performance improvement is due to the excellent
optical and electrical properties of theorganometal halide perovskite materials, such as
high absorption coefficient, long carrier diffusion
length, and low recombination rate.
In the PSCs investigation, the energy
diagram of the semiconductor material used forsolar cells is important for understanding thecharge separation process, and ultraviolet
photoelectron spectroscopy (UPS) with He lights
sources (21.22 and 40.81 eV) frequently used toobtain such information. A better understandingof the electronic structure of perovskite materials
used in PSCs is essential for their performance
improvement. In particular, photoelectron
spectroscopy (PES) can provide uniqueinformation at the atomic level of properties of
the interfaces.
In this study, we aimed to establish a method
to investigate the valence band of perovskite
crystals using soft x-ray photon energy (SX-PES).

3. Results and Discussion
3.1 Interpretation of the valence band
structure
To validity was verified by comparing thevalence band of the perovskite polycrystalline
thin film obtained by SX-PES with the result ofdensity functional theory (DFT) calculations.
The valence band of the perovskite
polycrystalline layer was delineated by SX-PES
measurements (Figure 1). The results of DFT
calculations of the CH3NH3PbI3 model5,6 wereassigned to the main structures observed in theexperimentally observed valence band. The
valence band formed from two components
consists of the mixed orbital of Pb 6s - I 5p*, andthe other component consists of Pb 6s - I 5p. The
overlap of these orbitals is broadened in the
crystal by dispersion in the band and formationof the lowest state in the conduction band. It is
confirmed that the measured data with SX-PES

2. Experiments
The perovskite polycrystalline thin film
used for the measurement was manufactured
according to the same experimental conditions
and protocol as the previously publishedliterature.4 Solutions (1.3 M) of CH3NH3PbI3 of24

Counts

20000

in Figure 3. The results of SX-PES and UPS werein agreement. From the above results, it was
confirmed that SX-PES can be evaluated up to
the bonding state of the elements forming thevalence band.

Pb 6s-I 5p*

Pb 6s-I 5p

10000

40000

30000

7

6

5

4

3

2

1

Counts00

Binding energy (eV)

20000

10000

Figure 1 Measurement results of the valence band
and Fermi level of the perovskite layer(CH3NH3PbI3) with photon energy of 100 eV.

050References[1] A. Kojima, K. Teshima, Y. Shirai, T.
Miyasaka, Organometal Halide Perovskites as
Visible-Light Sensitizers for Photovoltaic Cells,
J. Am. Chem. Soc. 131 (2009) 6050-6051.
[2] E.H. Jung, N.J. Jeon, E.Y. Park, C.S. Moon,
T.J. Shin, T.-Y. Yang, J.H. Noh, J. Seo, Efficient,stable and scalable perovskite solar cells using
poly(3-hexylthiophene), Nature, 567, (2019)511-515.
[3] Q. Jiang, Y. Zhao, X. Zhang, X. Yang, Y.
Chen, Z. Chu, Q. Ye, X. Li, Z. Yin, J. You,
Surface passivation of perovskite film for
efficient solar cells, Nature Photonics, 13, (2019),
460-466.
[4] N. Shibayama, H. Kanda, T. W. Kim, H.
Segawa, S. Ito, APL Mater. 7, (2019), 031117.
[5] V. D’Innocenzo, G. Grancini, M. J. P. Alcocer,
A. R. S. Kandada, S. D. Stranks, M. M. Lee, G.
Lanzani, H. J. Snaith, A. Petrozza, Nat. Commun.
5, (2014) 3586.
[6] K. Tanaka, T. Takahashi, T. Ban, T. Kondo, K.
Uchida, N. Miura, Solid State Commun. 127,
(2003) 619.

Int. (a. u.)

850

1Conclusions
We established a method to evaluate theformation state of the valence band of perovskite
polycrystalline thin films using SX-PES
measurement. The findings obtained this knowledge
could be used in the material design of perovskite
crystals.

FHWM 780nm
1.59 eV800

2Figure 3 Measurement result of the Fermi levelof Perovskite layer using UPS

3.2 Estimation of the Fermi level
To deep understand the junction state, it isimportant to accurately determine the Fermi levelof the semiconductor layer constituting aperovskite solar cells. In SX-PES measurement,
the Fermi level corresponds to 0 eV from the riseof the Valence band edge. The difference
between the valence band edge and the Fermi
level of the produced perovskite polycrystalline
thin film was 1.1 eV using SX-PES measurement.
The band gap of perovskite polycrystalline thinfilm(CH3NH3PbI3) of perovskite polycrystalline
thin film was 1.59 eV from photoluminescence(PL) spectra (Figure 2), which showed to be an
n-type semiconductor.

750

3

Binding energy (eV)were in good agreement with the model predictedby the DFT calculations.

700

4

900

Wavelength (nm)Figure 2 Measurement result of PL of theperovskite crystal layer. Excitation wavelength is
432 nm.
The measurement result of UPS with He
1α line (21.22 eV) of a perovskite layer is shown

25

Evaluation of La doping effect in Sr2IrO4
R. Horie1, S. Tsunoda2, Y. Haruyama3, and J. Akimitsu1
Research Institute for Interdisciplinary Science, Okayama University, 2Graduate School ofnatural science and technology, Okayama University, 3LASTI, University of Hyogo

1

Abstract

The 5d-electron system iridium oxide Sr2IrO4 is expected to become a high-temperature
superconductor by doping carriers. We succeeded in synthesizing the highest electron-doped iridiumoxide single crystal Sr1.88La0.12IrO4 which has not been reported worldwide. However, a hightemperature superconductor has not been realized yet. In this material the effectiveness of the carrier
doping by La doping is crucial. Hence, we examined the effect of La doing onto the valence of Ir
and Sr by measuring core-level photoelectron spectroscopy using New-SUBARU synchrotron
radiation (SR) facility. The narrowing effect of the core-level photoelectron peak has been found.
These results are different from our original expectation of the chemical shifts of Ir 4f or Sr 3d corelevel. However, these results of the peak width narrowing may suggest some doping effect.

Introduction
The iridium oxide Sr2IrO4 of the 5d electron
system has a layered perovskite type (K2NiF4type) structure, which has the same crystal
structure as La2CuO4 which is one of the mothersubstances of a copper oxide high-temperature
superconductor. Its electronic structure is alsosimilar. Hence it is expected that doping Sr2IrO4
with carriers may realize a high-temperature
superconductor with multiple similarities such as
magnetic structure, ARPES band structure and soon [1-3]. Sr2IrO4 is an antiferromagnetic insulator,
and it is expected that a superconducting phasewill appear over the antiferromagnetic metal
phase with about 20% electron doping [2]. The
author has succeeded in growing a single crystal
with the highest La doping concentration in theworld, La 0.2 (feed ratio) (Fig. 1). However, thesuperconductivity has not been realized yet. In

Fig.1 Single crystals of Sr1.88La0.12IrO4.
facility, the University of Hyogo.
Figure 2 shows the setting of the sample on thesample holder. A clean surface of the sample wasobtained by cleaving it in a preparation chamberat ~2.0 × 10 6 Pa by pushing the Cu rod attachedon the sample as shown in Fig. 2. The vacuum of
the main chamber at the time of XPS
measurement was ~1.2 × 10 7 Pa.

this material the effectiveness of the carrier
doping by La doping is crucial. Hence, we
examined the effect of La doing onto thevalence of Ir and Sr by measuring core-level
photoelectron spectroscopy using NewSUBARU synchrotron radiation (SR) facility.

In this study, using Sr2IrO4 and La-doped single
crystals with various concentrations, we aimed toevaluate the change in the valence of Ir and Sr
due to La-doping, and to obtain knowledge about
the doping concentration and condition suitableto realize superconductivity.

Fig.2 Sample setting.

Experiments and Results
The single crystal of Sr1.88La0.12IrO4 wassynthesized as shown in Fig. 1. X-ray
Photoelectron Spectroscopy (XPS) experiments
were performed at the beamline 07B end-stationof the New-SUBARU synchrotron radiation (SR)

Figure 3 shows the La 4d XPS spectrum fromSingle crystal Sr1.88La0.12IrO4. We could clearlyobtain the doped La core-level peak. We could
confirm that we can make holography
experiment on La to elucidate the function of
doped La atom.

26

La 4d5/2

La 4d

3/2

Ir 4f7/2

Ir 4f
Counts (arb. units)

Counts (arb. units)

5/2

115

110

105

100

95

80

Binding Energy (eV)

Sr 3d

5/2

Counts (arb. units)with La 1with La 2
without La

142

140

138

136

65

60

(red and blue) and without La doping (Sr2IrO4)(gray). The Ir 4f core peak from single crystal
without La doping (Sr2IrO4) (gray) does not show
clear two peaks again, but those of La doping(Sr1.88La0.12IrO4) (red and blue) show clear twopeak structure which is the spin-orbit split of Ir 4f
core. Hence, this spin-orbit split become more
visible by La doping. These results are different
from our original expectation of the chemical
shifts of Ir 4f or Sr 3d core level. However, theseresults of the peak width narrowing may suggest
some doping effect. Some theoretical works may
be required to explain these narrowing effects.
The fact that we could observe the La 4d peaks
is an important base of the photoelectron
holography experiment in SPring-8, which
realized as the proposal and execution of theexperiment in 2018.

Figure 5 shows the Ir 4f XPS spectrum fromsingle crystal with La doping (Sr1.88La0.12IrO4)

144

70

Fig. 5 Ir 4f XPS spectrum from single crystals
with La doping (Sr1.88La0.12IrO4) (red andblue) and without La doping (Sr2IrO4) (gray).

Figure 4 shows the Sr 3d XPS spectrum fromsingle crystal with La doping (Sr1.88La0.12IrO4)(red and blue) and without La doping (Sr2IrO4)(gray). The Sr 3d core peak from single crystal
without La doping (Sr2IrO4) (gray) shows only
one broad peak but those of La doping(Sr1.88La0.12IrO4) (red and blue) show flat or evendip structure at the top of the peak. These two
peak structures are the spin-orbit split of Sr 3dcore. Hence, this spin-orbit split become more
visible by La doping.

3/2

75

Binding Energy (eV)Fig.3 La 4d XPS spectrum from Single
crystal Sr1.88La0.12IrO4.

Sr 3d

with La 1with La 2
without La

References[1] B. J. Kim, et al., Science 323 (2009)1329.
[2] H. Watanabe, et al., Phys. Rev. Lett. 110(2013) 027002.
[3] K. Terashima, et al., Phys. Rev. B 96 (2017)041106(R).

134

Binding Energy (eV)Fig. 4 Sr 3d XPS spectrum from single crystals
with La doping (Sr1.88La0.12IrO4) (red andblue) and without La doping (Sr2IrO4) (gray).

27

Quasi-free-standing monolayer hexagonal boron nitride on
NiSatoru Suzuki1, Yuichi Haruyama1, Masahito Niibe1, Takashi Tokushima1, Akinobu Yamaguchi1, Yuichi Utsumi1,
Atsushi Ito2, Ryo Kadowaki3, Akane Maruta3, and Tadashi Abukawa3
1
LASTI, Univ. of Hyogo, 2Graduate School of Engineering, University of Hyogo, 3Institute of Multidisciplinary
Research for Advanced Materials, Tohoku University

Abstract

The electronic structure of monolayer hexagonal boron nitride grown on Ni by the diffusion andprecipitation method was studied by x-ray absorption spectroscopy, emission spectroscopy, x-ray
photoelectron spectroscopy and micro-ultraviolet photoemission spectroscopy. No indication of
hybridization between h-BN π and Ni 3d orbitals was observed. That is, the monolayer h-BN was
found to be in the quasi-free-standing state. These results are in striking contrast to those of previous
studies in which h-BN was strongly bound to the Ni surface by the orbital hybridization. The absenceof hybridization is attributed to absence of a Ni(111) surface in this study. The lattice-matchedNi(111) surface is considered to be essential to orbital hybridization between h-BN and Ni.

Introduction
Hexagonal boron nitride (h-BN) is a structural
analogue of graphene. Now, monolayer h-BN isusually grown on transition metal substrates, such as
Ni using chemical vapor deposition (CVD). In bulkh-BN, the neighboring layers are very weakly boundby the van der Waals interaction. However, previous
studies using core level spectroscopies have shown
that, in the CVD-grown h-BN/Ni system, there isstrong hybridization between h-BN π and Ni 3dorbitals and that h-BN is chemisorbed on the Ni
surface [1, 2]. Similarly, indications of strong
hybridization have been also observed in h-BN/Nisystems grown by molecular beam epitaxy (MBE)[3]and by ion beam sputtering deposition methods [4].
Theoretical calculation even predicts that the large
band gap of h-BN will disappear because of
hybridization of the h-BN π state with Ni 3d at the
Fermi level and that h-BN on Ni is metallic [5].
The diffusion and precipitation method is anotherway to grow atomically thin h-BN films [6-9]. Thismethod utilizes only a solid phase reaction. Thus, it
is much safer than the CVD, which uses flammableand toxic gases as source and carrier gases. In thisstudy, monolayer h-BN was grown on Ni by the
diffusion and precipitation method, and the bonding
character between the monolayer h-BN and Ni,
which has not yet been addressed, was studied using
x-ray absorption spectroscopy (XAS), x-ray emission
spectroscopy(XES),
x-ray
photoelectron
spectroscopy (XPS), and photoemission electron
microscopy (PEEM) [10].
Experiments and Results

Submonolayer h-BN films were grown on Ni foilusing the diffusion and precipitation method, basedon our previous studies [6-9]. Briefly, a ∼100-nmthick amorphous boron nitride (a-BN) film wasdeposited on a Ni foil (Nilaco Co., thickness: 25 µm)
using the radio frequency magnetron sputtering
method. The a-BN/Ni samples were heated either inthe endstation of the beamline BL7B in the
NewSUBARU synchrotron radiation facility or in astand-alone PEEM apparatus. The heating
temperature and time were about 900 °C and 30
minutes, respectively. During the heating, a fractionof B and N atoms of the a-BN film diffused throughthe Ni foil and formed h-BN on the opposite face of
the Ni foil. The samples had been kept in an ultrahigh vacuum until XAS, XPS and PEEM
measurements were completed, without otherwise
mentioning.
XAS and XES measurements were performed at
the beamline BL7B and BL9A at NewSUBARU,
respectively. To our knowledge, this is the firstobservation of takeoff angle dependence of XES
from monolayer h-BN. In-situ PEEM observation
was performed in a PEEM apparatus (IS-PEEM,
FOCUS GmbH) equipped with a micro-analyzer [29,30]. Local work function measurements by selectedarea ultraviolet photoemission spectroscopy (microUPS) were also performed using the same apparatus.
A field emission scanning electron microscope(SEM) (JEOL, JSM-7001F) was used for ex-situ
electronbackscatter
diffraction(EBSD)
measurements and SEM observation.
As shown in Fig. 1(a), bulk h-BN (unoriented

28

Fig. 1. Polarized (a) B-K and (b) N-K XAS of monolayer h-BN/Ni and bulk h-BN.
powder sample) shows a sharp and strong exciton be simply proportional to sin2θ and cos2θ,
peak at about 192 eV in the B-K absorption spectrum, respectively (θ: incidence angle). The large
as denoted by A. This peak is caused by the transition polarization dependence indicates that the h-BNfrom B 1s to π* (2pz). The transition to σ* (2px, 2py) atomic sheet is oriented parallel to the Ni surface, as
components is observed at around 198 and 200 eV, as reasonably expected. The incidence angle of 35°
denoted by B and C. In the N-K spectrum, the almost corresponds to the magic angle at which antransition from N 1s to π* orbital is observed at about unpolarized spectrum is obtained. In good contrast to
402 eV. The small hump is observed at about 404 eV previous studies, the spectrum of h-BN/Ni is very
as denoted by A’’. Here, we use these denotations in similar to that of bulk h-BN and the peaks A’ and A’’
accordance with ref. 1. The transitions to σ* orbitals do not appear. Similarly, the N-K spectra of h-BN/Ni
are observed at around 407 and 409 eV, as shown in is very similar to that of bulk h-BN and no additional
Fig. 1(b). The excitonic effect is much less prominent features are observed. These results indicate that thein the N-K spectrum, meaning that the unoccupied π* monolayer h-BN grown by the diffusion andstate has larger B 2pz (smaller N 2pz) character. This precipitation method on the Ni foil almost sustains
can be basically explained in terms of the higher the original electronic structure of h-BN.
B-K and N-K XES of bulk h-BN are shown in Fig.
electronegativity of N than B; that is, a certain degree
2. Here, in the bulk h-BN sample, c axes ofof ionic character of B-N bonds.
In previous XAS studies of h-BN/Ni systems, the microcrystals are highly oriented by compressing. In
B-K spectra have been found to be considerably this case, considering both s- and p-polarized lightdifferent from those of bulk h-BN. At both lower and emission, intensities of π and σ symmetries arehigher energies of the original exciton peak, expected to be proportional to cos2θ and (1+sin2θ)/2,
additional broad spectral features appear (often respectively. In contrast to XAS, a prominent π peakdenoted by A’ and A’’) [1-3]. Alternatively, the sharp is observed at about 394 eV in N-K XES of bulk hexciton peak A becomes broader and less intense. In BN and is not observed in B-K XES because the π
the N-K spectrum, A’ peak also appears at about 398 electron more largely occupies the N 2pz than the BeV, at the low energy side of the threshold [1-3]. The 2pz orbital because of the specific ionic character of
A peak becomes less intense and the A’’ peak B-N bonding. The other peaks in the N-K spectrum
becomes much more intense. Both the newly are attributed to σ orbitals. In the B-K spectrum, both
appeared features A’ and A’’ have been shown to have π and σ spectra are broad and have considerable
π* symmetry [1, 3]. Based on these results, it has overlap. In a previous study on CVD-grown h-BN/Nibeen concluded that there is a large degree of [2], a gap state due to h-BN π-Ni 3d hybridization
hybridization between h-BN π (π*) and Ni 3d orbitals. was observed in the bandgap region (188-190 eV) in
Figure 1(a) also shows the polarized B-K B-K XES. Changes observed in N-K XES were much
spectrum of h-BN/Ni grown by the diffusion and more drastic. The π peak completely disappeared.
precipitation method. From SEM observation, the Instead, the spectral intensity was mostly transferredcoverage of monolayer h-BN was evaluated to be to the gap state (396-398 eV).
about 0.8. For a planar h-BN sheet, absorption
XES of h-BN/Ni obtained at three incidence (takeintensities of π* and σ* symmetries are expected to off) angles are also shown in Fig. 2. As shown in Fig.

29

Fig. 2. (a) B-K and (b) N-K XES of monolayer h-BN/Ni and bulk h-BN.
2(a), B-K XES of h-BN/Ni largely differs from bulk
h-BN and only a weak takeoff angle dependence isobserved, strongly suggesting that a spectrum ofsome form of B other than h-BN is superposed.
However, with the exception of a small amount ofexcess B and its oxide observed in XPS (not shown),no such considerable amount of another form of B
has been observed in surface sensitive techniques,
such as XAS (Fig. 1), XPS, micro-Auger
spectroscopy, or in cross-sectional transmission
electron microscope observation [6-8]. We think thatthe additional spectrum comes from B atoms that had
diffused in the Ni foil. As mentioned in our previous
report [6], the solubility of B in Ni reaches 0.3 at.%
at 1085°C, although the solubility of N is negligibly
small even at high temperatures. The B atoms in Ni
would remain inside when the sample was quenchedafter heating. Considering that XES is bulk-sensitive,
it is not surprising that the number of B atoms in the
probing depth is comparable to or larger than that of
0.8 ML of h-BN at the surface. Now, we would liketo focus on the bandgap region. No gap state isobserved in the h-BN/Ni sample, suggesting theabsence of h-BN π and Ni 3d hybridization. N-K XESof the h-BN/Ni sample is similar to that of h-BN, as
shown in Fig. 2(b). The incidence angle dependencesof the π and σ peaks are, again, consistent with theplanar h-BN sheet. As clearly seen in the figure, theπ peak still exists and the gap state does not appear.
These XAS and XES results are consistent witheach other and indicate that there is little
hybridization between h-BN π and Ni 3d and that hBN is physisorbed on the Ni surface. In other words,
the monolayer h-BN is in a quasi-free-standing state
on Ni, in striking contrast to the findings in previous
studies [1-4] in which h-BN was found to be strongly
bound to Ni by the hybridization.
The work function of CVD-grown h-BN on
Ni(111) (work function: 5.3 eV [1]) was reported tobe 3.6 eV [1]. That is, h-BN growth decreases thework function by 1.7 eV. The large work function
decrease strongly suggests electron transfer from hBN to Ni and dipole formation at the h-BN/Niinterface. Figure 3(a) shows a PEEM image of hBN/Ni. Bare Ni surface and h-BN domains areobserved darkly and brightly, respectively. The
contrast is mainly considered to be due to work
function change induced by h-BN formation. The
enhanced photoemission from the h-BN-covered
surfaces indicates that h-BN formation also decreases
the work function in our case. However, the work
function decrease is less prominent than in previous
studies. Figure 5(b) shows secondary electron spectra
obtained from several points. Curves A and B wereobtained from bare Ni surfaces, and curves C, D, andE were from h-BN/Ni. From the cutoff energies ofcurves A and B, the work functions of the Ni surfaces
are evaluated to be about 5.0 and 4.8 eV. The
difference is considered to be caused by thedifference in orientation of Ni grains due to thepolycrystalline structure of the Ni foil. The work
functions of h-BN/Ni are evaluated to be 4.6, 4.5, and
4.0 eV from curves C, D, and E. These values are
considerably larger than that in a previous report (3.6eV). The work function decreases are within a rangeof 0.2 to 1.0 eV, which also considerably lower thanthose in previous studies (1.7 eV). The relatively
large work functions and small work function
decreases suggest the absence of a large dipole at theh-BN/Ni interface and thus, the absence of large
charge transfer between h-BN and Ni.
Here, we discuss the possible reason for this. In
all the previous studies, single-crystalline Ni wasused, and monolayer h-BN films were grown on
Ni(111) surfaces [1-4]. However, the Ni foil used inthis study had a polycrystalline structure with atypical grain size of 100 µm. The z-direction EBSD
map reveals that there is no (111) face after the h-BN30

Fig. 3. (a) PEEM image of submonolayer h-BN/Ni. (b) Secondary electron spectra obtained from bare
Ni surfaces (A and B) and h-BN/Ni (C, D, and E). In (a), the grain boundaries are denoted by the dashedlines.
formation. The Ni(111) surface has a six-foldsymmetry. Its lattice constant is 0.249 nm, which is
close to that of h-BN (0.250 nm). The translational
symmetry may be essentially important for thechemisorption properties of h-BN/Ni(111). In thisstudy, the symmetry and lattice constant of the Ni
surface do not match those of h-BN at all. We thinkthat the lack of hybridization is due to the absence of
the Ni(111) surface in this study. That is, thehybridization between h-BN π and Ni 3d ischaracteristic of the Ni(111) surface, which matches
atomic structure of h-BN. Our results suggest that it
is possible to grow quasi-free-standing h-BN on Ni
by growth techniques other than the diffusion andprecipitation method by using a non-(111) Ni surface.

References[1] A. B. Preobrajenski et al., Surf. Sci. 582(2005) 21.
[2] A. B. Preobrajenski et al., Phys. Rev. B 77
(2008) 085421.
[3] D. Usachov et al., Phys. Rev. B 82 (2010)
075415.
[4] A. A. Tonkikh, Sci. Rep. 6 (2016) 23547.
[5] A. Miyashita et al., Phys. Rev. B 97 (2018)
195405.
[6] S. Suzuki et al., J. Phys. D: Applied Physics
45 (2012) 385304.
[7] S. Suzuki et al., J. Vac. Sci. Technol. B. 31(2013) 041804.
[8] S. Suzuki et al., Jpn. J. Appl. Phys. 56 (2017)
06GE06.
[9] S. Suzuki et al., Jpn. J. Appl. Phys. 58 (2019)
SIIB15.
[10] S. Suzuki et al., Mater. Ress Express 6(2019) 016301.

31Growth and Decomposition of Hexagonal Boron Nitride in
the Diffusion and Precipitation Method Studied by
X-ray Photoelectron Spectroscopy
Suzuki and Yuichi Haruyama,
LASTI, University of Hyogo

Abstract

Submonolayer h-BN was grown on Ni foil in ultra-high vacuum by the diffusion and precipitation
method and the growth and decomposition processes were studied by x-ray photoelectron
spectroscopy. Formation of h-BN started at 600 C. All through the process, the surface was always
slightly B-rich, which is consistent with the fact that B which is soluble in Ni at a high temperature
can diffuse in Ni by the conventional bulk diffusion and insoluble N cannot. Moreover, bothformation and decomposition of h-BN were found to be competing at elevated temperatures possibly
depending on provision of N atoms to the surface. On the Ni surface, decomposition of h-BN was
observed at a relatively low temperature of 800 C.

Introduction
The large chemically stability of hexagonalboron nitride (h-BN) is one of very important
properties for various applications. The thermal
decomposition temperature of bulk h-BN has beenreported to be extremely high (2127-2327 C).1)
Recently, chemical vapor deposition (CVD) is
commonly used for growth of large-area andatomically thin h-BN. CVD growth is normally
performed under gas flow with relatively high or
ambient pressure. Therefore, direct characterizationof the growth process by electron spectroscopy isvery difficult. In fact, there have been few reports onspectroscopic observation of the growth process ofh-BN CVD.
The diffusion and precipitation method is analternative way to grow atomically thin h-BN film.24) This method utilizes only solid phase reaction of ametal (Ni was used in this study) substrate and solid
source (a-BN). B and N atoms diffuse from thebottom surface to the top surface of the metal foil at
an elevated temperature and form h-BN on the top
surface. Therefore, h-BN can be grown in an ultrahigh vacuum (UHV). Thus, this method is very
suitable for analysis of growth process in a UHV
environment. In the diffusion and precipitation
method, it is considered that feeding mechanism of
B and N atoms to the surface is different. Although
B is known to be slightly soluble in Ni at hightemperature, the solubility of N is negligibly smalleven at high temperature. Grain boundary diffusion(in Ni) and surface migration (on top surface) wereconsidered to be responsible for feeding N atoms
from our previous studies. In this report, we studied
the growth process of monolayer h-BN in the
diffusion and precipitation method by using x-ray
photoelectron spectroscopy (XPS).5)

Experiments and Results
A submonolayer h-BN film was grown on Ni foilusing the diffusion and precipitation method, basedon our previous studies.2-4) Briefly, an amorphousboron nitride (a-BN) film (thickness: about 100 nm)
was deposited on a Ni foil (Nilaco., thickness: 25m) using radio frequency magnetron sputtering in
Ar/N2 atmosphere (Ar/N2 flow rate: 1 1). The aBN/Ni sample was loaded in the sample preparationchamber connected to the XPS analysis chamber at
BL7B in NewSUBARU. In the preparation chamber,Table 1. Sequential heating processes.

32

Processno.

Heating temperatureand time0

Before heating

1

600 C, 10 min

2

800 C, 10 min

3

800 C, 10 min

4

850 C, 10 min

5

850 C, 10 min

6

850 C, 10 min

7

850 C, 10 min

8

850 C, 10 min

9900 C, 10 min

10

900 C, 20 min

11

950 C, 10 min

121000 C, 10 min

B-N B-B(a)(b)(12) 1000 °C(12) 1000 °C(11) 950 °C(11) 950 °C

(10)

(10)

(9) 900 °C(8)(7)(9) 900 °C
(8)
(7)

(6)

(6)

(5)
(4) 850 °C

(5)

(3)

(4) 850 °C(2) 800 °C(3)(2) 800 °C(1) 600 °C(1) 600 °C(0) RT
200(0) RT
195
190
Binding energy (eV)

185

410

405
400
395
Binding energy (eV)Fig 1. (a) B 1s and (b) N 1s XPS obtained at each process. The numbers in parenthesis correspond to
the process numbers in Table 1.
the sample was heated at a certain temperature in arange of 600 to 1000 C by electron bombardment tothe a-BN-deposited face. Then, the sample wastransferred to the analysis chamber and XPS of
undeposited face was measured at room temperature.
Unmonochromatized Al K line (1486.6 eV) wasused for XPS measurements. Heating and XPS
measurements were repeated. Heating temperatureand time at each process were summarized in Table

B 1s intensity (arb. units)

N 1s intensity (arb. units)

1. In this study, the maximum h-BN coverage wasobserved at process 6 and estimated to be about 0.5
from B 1s (N 1s)/Ni 2p XPS intensity ratio.
B 1s and N 1s XPS obtained at each process areshown in Fig. 1. The N 1s signal centered at 399 eV
observed before heating (process 0) is not due to hBN formation, but surface nitridation during the aBN deposition, as mentioned above. In fact, the N 1s
binding energy differs from that of h-BN (397.6 eV),Fig 2. (a) B 1s and (b) N 1s integrated XPS intensity at each process. In (a), B 1s intensities from hBN and elemental B are shown, respectively. In (b), the initial N intensity observed at process 0 was
excluded in order to focus on N 1s intensity from h-BN.

33

Ni grain boundary
B
N
h-BN

a-BN

a-BN

Fig 3. Schematic model for formation and decomposition of h-BN. When provision of N atoms
through Ni grain boundary is large, formation of h-BN is dominant (left). When provision of N atoms
is small, decomposition becomes dominant (right).
and no B 1s signal is observed. The spectra showsthat h-BN formation slightly started at 600 C(process 1). In the B 1s spectrum, h-BN formation isstill barely visible. However, in the N 1s spectrum, asmall peak is observed at about 397.6 eV, whichcorresponds to N 1s binding energy of h-BN. Instead,the peak initially observed at 399 eV disappeared.
After annealing at 800 C and higher temperatures(process 2-12), h-BN formation is also clearlyvisible in B 1s spectra. However, the B 1s spectra
split into two peaks. The peak at 190.0 and 188.0 eV
are assigned to h-BN and elemental B, respectively.
The results indicate that feeding of B and N atoms
are not balanced, but the surfaces are B-rich. The
elemental B component is likely to appear on thesurface during cooling, because B is slightly solublein Ni at a high temperature.6) The B-rich surfaces are
consistent with our previous conclusion that h-BNformation is restricted by provision of N atoms to thesurface.2-4) The elemental B is quickly oxidized when
the sample is exposed to air, as shown in ourprevious report.7)
As can be seen in Fig. 1, the B 1s and N 1s intensity
evolution is not monotonic. Figure 2 shows B 1s andN 1s intensity evolutions obtained from Fig. 1. The
B 1s (B-N) and N 1s intensity evolutions arereasonably similar to each other due to h-BNformation. Interestingly, heating sometimes caused
B 1s and N 1s intensity decreases. Heating atconstant temperatures of 800 (processes 2, 3), 850(4-8), 900 C (9, 10), the B 1s and N 1s intensities
increased at first, and then, they declined. In thisheating process, further temperature increase merely
decreased the coverage of h-BN (11, 12). These
results indicate that not only formation of h-BN but
also decomposition occurs at these temperatures.
The decomposition was even observed at a relatively
low temperature of 800 C (process 3).
Recently, we could directly observe B atoms
solved in Ni foil after h-BN formation by using B-K
x-ray emission spectroscopy.7) This is consistent
with the fact that B is slightly soluble in Ni at a high34

temperature. Thus, B atoms can reach the top surface
by conventional bulk diffusion. On the other hand,
our previous study strongly suggest that provision of
N atoms is caused by grain boundary diffusion andsurface migration.2-4) Figure 3 shows a schematic
model for explaining the XPS intensity evolutions
observed in this study. Heating causes
recrystallization of Ni. Then, N atoms in the a-BN
film can reach the top surface through the grainboundary. N atoms migrate on the top surface andform h-BN by bonding to B atoms. This study showsthat formation and decomposition of h-BN arecompeting at the elevated temperatures. At first, theprovision of N atoms is relatively large andformation of h-BN is dominant. However, repeatedheating (processes 3, 7, 8, 10-12) results in decreased
provision of N atoms. Then, decomposition becomesdominant. We think that h-BN layers formed at thea-BN/Ni interface2) is highly responsible for thedecrease of N atom provision. The h-BN layers
would act as a barrier for N atoms in the a-BN film
to diffuse into the Ni foil. We did not observe any N
1s signal other than N-B bond in XPS except forprocess 0. Thus, insoluble N atoms created bydecomposition are released to vacuum possibly byforming inert N2 molecules. B atoms created bydecomposition can either melt into Ni or remain on
the surface.
Decomposition of h-BN was observed at a
relatively low temperature of 800 C. Thistemperature is much lower than the decomposition
temperature of bulk h-BN (2127-2327 C).1) A
catalytic effect of the Ni surface is also considered to
be important for decomposition of h-BN at such a
low temperature.
References[1] S. Gleiman et al., J. Mater. Sci. 37 (2002)
3429.
[2] S. Suzuki et al., J. Phys. D: Applied Physics
45 (2012) 385304.

[3] S. Suzuki et al., J. Vac. Sci. Technol. B. 31(2013) 041804.
[4] S. Suzuki et al., Jpn. J. Appl. Phys. 56 (2017)
06GE06.
[5] S. Suzuki et al., Jpn. J. Appl. Phys. 58 (2019)
SIIB15.
[6] P. C. Yang et al., J. Electric. Mater. 34 (2005)
1558.
[7] S. Suzuki et al., Mater. Ress Express 6 (2019)016301.

35

Analysis of chemical reactions at the Au-thin-film/Siinterface by soft x-ray photoelectron spectroscopy
under steam ambient
Tomoki Yamamoto1, Satoshi Toyoda2, Satoru Suzuki1, Hirosuke Sumida3,
Susumu Mineoi3, Kazushi Yokoyama1, Akitaka Yoshigoe4, and Shizuka Nishi4
1
Univ. of Hyogo, 2Tohoku Univ, 3Mazda, 4JAEA

Abstract

We focused on the alloying reaction at the contact interface of Au and Si, and traced the reaction
process by soft x-ray photoelectron spectroscopy in H2O atmosphere with heating the Au/Si sample.
In this study, it is suggested that H2O atmosphere promotes Au/Si alloying even at a very low partialpressure of 1x10-6 Pa.

Introduction
To improve the function of semiconductor
devices such as diodes and transistors, manystudies have been conducted on the reaction
control at the contact interface between
semiconductor and metal. Among them, it is
known that an interesting phenomenon occurs at
the interface between semiconducting Si andmetallic Au. Although the eutectic point of bulk
Si and Au is 370 °C, when Au thin film isdeposited on the Si substrate, Si atoms diffuse into
Au at a temperature lower than 370 °C and SiO2
is formed on the Au surface. Even at room
temperature, the diffusion of Si can be observed if
Au/Si sample is left for about two weeks [1].
From these phenomena, Au/Si has been studied
by various surface analysis methods as animportant alloy system for interface control ofsemiconductor devices. We are conducting
research with the aim of establishing a technology
for quantitatively analyzing chemical reactions
that occur at material interfaces fromphotoelectron spectroscopy data, using this Au/Si
interface as a model system. Here, we report the
influence of H2O atmosphere on the reaction of
Au/Si system [2].
Experiments and Results
The experiments were carried out at SPring-8
BL23SU by using atmosphere controlled soft xray
photoelectron
spectrometer(surfacechemistry experimental station). A water
exposure device was added to the analysis tank tointroduce H2O into the analysis chamber. The
alloying temperature of Au/Si was observed by
the shift of the binding energy of the Au4f5/2 and
4f7/2 levels accompanying alloying, as shown in
Figure 1.

Fig.1. Au 4f photoelectron spectra obtained atvarious temperatures. The positions of peak
tops are determined by fitting Au4f5/2 andAu4f7/2 respectively with Pseudo Voigt
function.
A sample with an Au film deposited up to a
thickness of about 60 nm on a Si substrate wassubjected to photoelectron spectroscopy
measurement with raising the temperature of thesample.
Figure 2 shows the temperature dependence of
the Au4f binding energy of Au/Si sample (Au/Si(VAC)) and Au/mica sample (Au / mica (VAC))
in ultra-high vacuum (1x10-8 Pa), and Au/Si
sample (Au/Si (H2O)) under H2O atmosphere (1.0
x 10-6 Pa).

36

In the sample where Au was deposited on mica,
alloying was not observed even when heated to
500 . However, when the Au/Si sample wasmeasured in H2O atmosphere, the transition
temperature was lowered to about 225 ℃. Whenmeasured even under an O2 atmosphere (1×10 4Pa) before, the transition temperature waslowered to the same extent [3], but this time it isunder a pressure about 100 times lower. Thus, it
is considered that the H2O atmosphere has afunction to promote the alloying of Au/Si even ata very low partial pressure of 1×10 6 Pa.
Fig. 2 Temperature dependence of Au4f
binding energy of Au/mica and Au/Si samples

References[1] A. Hiraki et al., J. Japan Inst. Met. 15, 665(1976)[2] T. Yamamoto et al., 80th Japanese Society ofApplied Physics Autumn Meeting 2019,
September 2019, Sapporo, 20a-E318-5.
[3] S. Toyoda et al., 79th Japanese Society ofApplied Physics Spring Meeting 2018,
September 2018, Nagoya, 18p-212B-7.

37

Soft X-ray absorption and Emission Spectroscopy ofMonolayer and Few-layer Graphene Sheet
Masahito Niibe1, Satoru Suzuki1, and Shin-ichi Honda2.
LASTI, University of Hyogo, 2Graduate School of Eng., University of Hyogo

1

Abstract
We measured soft X-ray absorption (XAS) and emission (XES) spectra in C K-edge region ofmonolayer and few-layer graphene including incident/take-off angle dependence, in the BL-09A at
the NewSUBARU SR Facility. Spectra similar to HOPG, which is a standard substance, wereobtained for both the XAS and the XES. However, the incident/take-off angle dependence of π/σratio was smaller than that of HOPG. The band structure of monolayer graphene constructed using
the results of XAS and XES spectra has the characteristics of a semimetal.
Introduction
From pioneering experiments on twodimensional (2D) graphene by A. Geim and K.
Novoselov [1], graphene is noted as a Van der
Waals 2D layered material, and much research has
been performed from both basic and applied aspects.
In particular, monolayer graphene has a unique band
structure called Dirac cone and has a very large
electron mobility [2], and thus is attracting attention
as a next-generation semiconductor device material.
From these backgrounds, information on theelectronic state of monolayer graphene is very
important in the nano-carbon field.
As an effective means for directly observing theband structure of a solid state substance, there is amethod using soft X-ray absorption spectroscopy(XAS) [3] and emission spectroscopy (XES) [4] incombination. The spectrum of XAS reflects thedensity of states of the conduction band of the solid,
while XES can obtain information of the valenceband. An excellent report has been made by Pacile
et al. on C-K absorption spectra of graphene sheetsfrom a monolayer to five or more layers [5].
Although the XES spectra of monolayer graphene
are reported by Zhang et al. [6] and IIkov et al. [7],their energy resolution is not sufficient. And also,
the take-off angle dependence of the soft X-ray
emission has not been reported.
We have developed a soft X-ray emission
spectrometer that can measure the K-emission oflight elements such as boron (B), carbon (C),nitrogen (N) and oxygen (O) with high energy
resolution in the NewSUBARU SR Facility at the
University of Hyogo [8]. As a result, we havereported on the large take-off angle dependence of
the XES spectra of highly oriented pyrolytic
graphite (HOPG) [9]. We have also reported the B
K-emission spectrum of a trace (0.32%) B-doped
HOPG sample [10]. Therefore, the spectrometer issuitable for emission spectroscopy of light element
films of monoatomic layer. We have prepared nano-carbon materials of monolayer and few-layer andtried to measure the soft X-ray absorption andemission spectra at the C K-edge region.
Experiment
The measured samples are a graphene sheet inwhich a monolayer graphene (Graphene Platform
Corp.) and a few-layer of graphene (National
Taiwan University of Technology and Science)grown on Cu substrates. The monolayer graphenesample was transferred onto a SiO2 (285nm)/Si
substrate by using commonly used PMMA method[11]. With regard to few-layer graphene, graphenegrown by CVD method on a Cu substrate was
exfoliated by etching the underlying Cu in FeCl3
solution, and it was fixed on a Si substrate byskimming it. The number of layers of few-layer
graphene is estimated to be 2 to 3 from the 2D/G
ratio (= 0.816) of the Raman spectrum.
The soft X-ray absorption and emission spectra
were measured at the “Long Undulator” beamline
BL-09A at the NewSUBARU SR facility [12].
Absorption spectroscopy was based on the total
electron yield (TEY) method using sample current
measurement. The emission spectra were measured
with the excitation energy of 310 eV, which isconsidered to be non-resonant condition at the C Kedge. The XES spectrometer is placed to receive anemitted X-ray beam in a direction rotated 90° fromthe incident beam in the horizontal plane. The
incident light is linearly polarized, where theelectric vector is in the horizontal direction. In thisstudy, the incident/take-off angle dependence of thespectrum was also measured by rotating the sample
manipulator around the vertical axis. Here, theincident angle in the XAS measurement isrepresented as an angle measured from the sample
surface normal, and the take-off angle in the XES

38

Monolayer Graphene on Cu_C-K

Normalized absorption [a.u.]

Normalized absorption [a.u.]2

1.5

60 deg.

1

35 deg.

0.5

0 deg.

Normalized absorption [a.u.]25
2.5

60 deg.

30 deg.

0 deg.

20

15
60 °
10
30 °
5
0°

0
0

280

290

300

310

320

280

290

300

Photon energy

Photon energy [eV]

310

0

320

280

[eV]

290

300

310

320

Photon energy [eV]

(a)
(b)
(c)
Fig 1. Incident angle dependence of C K-edge absorption spectra of (a): monolayer graphene, (b): fewlayer graphene, and (c): HOPG as reference.

measurement is represented as an angle measured
from the sample surface.

C K-edge emission spectra of (a): monolayer
graphene, (b): few-layer graphene, and (c): HOPG
as reference [9]. Although, soft X-ray emission frommonolayer graphene is considered to be very weak,
one of these spectra could be acquired at an
exposure time of 20 to 30 min.
The emission intensities change depending on the
take-off angle, but when normalized so that therising part of 277 eV or less (lower energy side footof the peak) become equal, it can be roughly divided
into two components depending on or independentof the take-off angle. They are component with lessangle dependence of about 280 eV or less and theangle dependent peak at 282 eV. These take-off
angle dependences are similar to that of HOPG
previously reported by us [9], and it can be
identified that the peak of 280 eV or less is derived
from the σ orbital and the peak at 282 eV is derived
from the π orbital of graphene/graphite honeycomb
network.
The incident angle dependence of the ratio of theπ peak to the σ peak, ie, the π/σ ratio, appears to havea smaller rate of change than that of HPOG in both
the XAS and XES spectra. As one of the reasons, it

Results
Figure 1 shows the incident angle dependence ofC K-edge absorption spectra of (a): monolayer
graphene, (b): few-layer graphene, and (c): HOPG
as reference [13]. For the C-K absorption spectrumof monolayer and few-layer graphene samples,
spectra similar to HOPG was obtained. In particular,
the π* peak around 285.4 eV has a very small
intensity at an incident angle of 0 deg., andsignificantly increases with the increase of theincident angle. In the spectra of monolayer and fewlayer graphene, multiple peaks not observed in
HOPG were observed in the region of 287 to 290 eV.
These are considered to be peaks derived from anairborne contamination carbon-oxide. Monolayer
graphene is thought to be relatively stable andoxidation does not proceed even in the atmosphere.
Therefore, the oxide observed here is considered to
be derived from the contaminant deposited on thegraphene during the sample storage in air [14].
Figure 2. shows the take-off angle dependence of
π

35 °

70 °

15°
30°
45°

σ

π

Emission intensity [a.u.]σπEmission intensity [a.u.]

Emission intensity [a.u.]

15 °

60°
75°

α=15°

30°

45°

σ
60°
75°

0

260

265

270

275

280

285

Photon energy [eV]

290

295

0
260

265

270

275

280

285

Photon energy [eV]

290

295

0

260

265

270

275

280

285

Photon energy [eV]

290

295

(a)
(b)
(c)
Fig 2. Take-off angle dependence of C K-edge emission spectra of (a): monolayer graphene, (b): fewlayer graphene, and (c): HOPG as reference.

39

has been reported that when a monolayer / few-layer
graphene was transferred to a SiO2 / Si substrate,
corrugation or wrinkles in the film was generated[15].
Figure 3 shows the band structure of monolayer
graphene obtained by combining the results of XAS
and XES measurements. As can be seen from thefigure in the monolayer graphene, the valence bandand the conduction band are in contact at an energyof about 284 eV measured from C1s level, and havea semi-metallic property.

Emission/Absorptin intensity [a.u.]

XES

are similar to that of the standard sample of HOPG.
However, the incident/take-off angle dependency ofπ/σ ratio was smaller compared to HOPG. An oxide
peak was observed in the spectrum of monolayer
and few-layer graphene, which is considered to be
derived from airborne contamination on the surface.
References[1] A. K. Geim and K. S. Novoselov: Nature
Materials 6, 183–191 (2007).
[2] J. Avila et al.: Sci. Rep. 3 02439 (2013).
[3] J. Stoehr: NEXAFS Spectroscopy (Springer
Berlin, 2003).
[4] U. Bergmann, and P. Glatzel: Photosynth. Res.,
102, 225 (2009).
[5] D. Pacile et al.: Phys. Rev. Lett., 101, 066806(2008).
[6] L. Zhang et al.: Phys. Rev. B 86, 245430 (2012).
[7] B. IIkiv et al.: J. Nanosci. Nanotechnol., 12,8913-8919 (2012).
[8] M. Niibe and T. Tokushima: AIP Conf. Proc.,
1741, 030042 (2016).
[9] M. Niibe, et al., J. Electron Spectrosc. Relat.
Phenom., 220, 118-120 (2017).
[10] M. Niibe, N. Takehira and T. Tokushima, e-J.
Surf. Sci. Nanotechnol., 16, 122 (2018).
[11] S. Suzuki et al., J. Phys. Chem. C 117, 22123(2013).
[12] M. Niibe et.al.: AIP Conf. Proc. 705, 576(2004).
[13] R.A. Rosenberg et al.: Phys. Rev. B 33, 4034
(1986).
[14] Z. Li et al.: Nature materials 12, 925 (2013).
[15] V. Lee et al.,: J. Phys. Chem. Lett. 1, 1247
(2010).

XAS

0

260

270

280

290

300

310

Photon energy [eV]Fig 3. Combining results of the XES and XAS
spectra of monolayer graphene (band structure).
As summary, we were able to measure for the firsttime soft X-ray absorption and emission spectra at
C K-edge of monolayer and few-layer graphene,
including dependence of incident/take-off angles.
The shapes of the absorption and emission spectra40

Photopolymer Technology for Extreme Ultraviolet
Lithography
Takeo Watanabe, Tetsuo Harada
Center for EUVL, LASTI, University of Hyogo
Abstract
EUV (extreme ultraviolet) lithography is the next generation lithography for the fabrication of semiconductor
electronic devices in 10 nm node and beyond. The research group which was involved in national EUVL projectin Japan has been processing the research and development of EUV lithographic technology including resist andmask technologies in collaborating with many research institutes, companies, and university in worldwide. This
paper focuses on the development of EUV resist technologies including materials and evaluation tools for its
exposure characteristics. The research group of University of Hyogo is playing an important role for the processing
the EUV technology in worldwide. The future prospect for EUV lithographic technology is also discussed.
Keywords: EUV lithography, EUV resist, sensitivity, LER

system between mask and wafer stages to enlarge
the exposure area to be 30 mm×28 mm, which canfabricate two chips of DRAM. This was acollaboration work between University of Hyogo,
Hitachi Central Research Lab. and Nikon researchgroups [2]. The three aspherical mirror optics was
design by University of Hyogo in 1997 [3]. From1999 to 2001, this work continues to thecollaboration with University of Hyogo and
ASET [4]. Figure 1 shows the EUV exposure tool
which was developed at University of Hyogo andwhich was installed at BL03 beamlines of
NewSUBARU. The figure error of eachaspherical mirror was 0.58 nm in rms, and thesubstrate was ZerodurTM. The exposure
wavelength and numerical aperture were 13.5 nm
and 0.5.

Introduction
The semiconductor market is announced to be
421 billion dollars in 2017, and it achieved 21.7%
market growth in comparison with total market of2016. The market growth of Internet of Things(IoT) own to the advanced lithographic
technology, because the advanced lithographic
technology can lead semiconductor devices tohave the low power consumption, low fabrication
cost, fast speed data acquisition of large scaled
data. According to the many progress oftechnologies related to Extreme ultraviolet
lithography (EUVL), EUVL are facing to use inhigh volume manufacturing as an advanced
lithographic technology for the fabrication ofsemiconductor devices around 2019. However,technical issues of EUVL for HVM still remains,which are the development of 1) EUV light sourcewith high power and high stability, 2) EUV resist
which satisfies high resolution, high sensitivity,
low line edge roughness (LER), and low
outgassing simultaneously, 3) EUV pellicle toprotect from the particles from the surface of EUV
mask, 4) defect free EUV mask including
metrology. The research and development of
EUV technology has been carried since 1995 atUniversity of Hyogo. In 1989 NTT research groupdeveloped two aspherical imaging system, the 150
nm resist pattern was replicated. In 1996
semiconductor market required more advanced
patterning tool using EUV lithography which canuse in the production line to fabricate
semiconductor devices. Thus, at NewSUBARU[1] synchrotron light facility of University of
Hyogo, three aspherical imaging optics were
designed and fabricated for the pattering of 70 nm
hp on a 8 inches wafer using the synchronizedFig.1. World 1st large exposure field EUV
exposure tool for advanced lithography
employing three aspherical mirror imaging optics
for the patterning 60 nm resist pattern bysynchronizing mask and wafer stages.

41

We succeed to replicate 60 nm hp and 45 nm
isolated resist pattern on a 8 inches wafer with alarge exposure area [4]. At NewSUBARU
synchrotron light facility opened for common
usage for EUVL, and Center for EUVL wasestablished in 2010. Many companies, research
institutes, and universities are visiting to use the
EUV resist evaluation tools such as sensitivity
measurement tool, EUV interference exposure
tool, resist outgassing evaluation tool, resist
transmission measurement tool, the soft X-ray
absorption evaluation tool for EUV resist
chemical reaction analysis, and the bright-field
EUV microscope and EUV coherent EUV
scatterometry microscope for EUV mask defectinspection. These tools were installed at BL03,
BL09, and BL10 beamlines of NewSUBARU
which are introduced in Fig 2. The paper focusesand describes the detail of the EUV resist
evaluation tools. In addition, it describes EUV
PAG bounded polymer resist for low LER. On abasis of these research and development, theadvanced progress of EUV lithography for HVM
is contributed.

which is shown in Fig.3(a) was introduced,
designed, and synthesized [5-8], to reduce lineedge roughness (LER) and increase sensitivity fora resist in extreme ultraviolet lithography (EUV)and electron beam (EB) lithography. A sulfonium
salts group was supplied at side chain of basepolymer system. The base polymer consists ofcopolymer of polyhydroxy styrene, solution
inhibitor and monomer containing PAG as a
backbone. Under EB exposure, a LER of 2.0 nm(3 ) is achieved using PAG bounded polymer. A
LER of PAG bounded polymer is smaller than thatof PAG blended polymer as shown in Fig.3(b).
Under EUV exposure, E0 sensitivity of 0.9 mJ/cm2
and low outgassing characteristics are achieved.
Finally, it is succeeded to reduce LER to be 1/2
size with comparison of conventional CAR.
Table 1. The expected origins of LER whichcauses stochastic.
1) Spatial distribution of functional material
inresistfunctionalgroups,photosensitizers (photoacid generators),
additives such as amines, etc.
2) Solvent distribution in prebake process
Spatial distribution of free volume3) EUV photon shot noise4) 2ndry electron blur5) Solvent effect in PEB process
Acid diffusion
6) Development and rinse effects
Spatialdistributionofdeveloper
penetration and development process yield7) Out of band (OoB) light effectFig. 2. Three beamlines such as BL03, BL09, andBL10 beamlines dedicate for research anddevelopment for resist and mask in EUV
lithography.
EUV PAG bound resist for low LER and highsensitivity
As for EUV resist development, the mostsignificant issues are the achievement of low LER
and high sensitivity simultaneously. Specially toachieve of LER, the stochastic issue should be
resolved. The LER causes by many origins whichwere listed in Table 1. We expected the mostsignificant origin of stochastic is the spacial
distribution of the chemical content such as PAG
in the resist film in the case of chemical amplified
resist (CAR). The PAG bounded polymer for CAR

Fig. 3. PAG bound polymer and PAG blended
polymer in chemically amplified resist materials.
EUV interference lithographic exposure tool
To accelerate the EUV resist development of
10-nm order, it is very significant to develop the
EUV interference lithographic (EUV-IL) [9]exposure tool. The EUV interference lithography
had been developed and replicated 15 nm line and42throughput and resist pattern replication
resolution. This contamination should be reduced
to maintain the lithographic performance; thus,
therelationshipbetweenthecarboncontamination and the outgassing species should
be clarified.
ASML proposed a double-electron beam (EB)system to evaluate the contamination. They used
one EB gun for exposure of the resist to induce
outgassing from the resist, and they used anotherEB gun for exposure of the Mo/Si witness sample
to reduce the adhesion of the contaminant.
Because the outgassing and contamination
efficiency seem to be quite different under EB and
EUV exposure conditions, it is necessary tocompare the contamination and outgassing
behavior between the two types of exposure. It isalso necessary to study the differences incontaminant adhesion between the exposure using
a low EUV power and the exposure using a high
EUV power that is comparable to that used in
HVM EUV lithography. The novel tool for in situ
evaluation of contaminating carbon layer
thickness was therefore developed using an EUV
power as high as that used in HVM. The
photograph of this contamination evaluation
system is shown in Fig. 5., and it was installed in
the 10.8-m-long undulator BL-09C beamline at
the NewSUBARU. This system has the quadropole mass spectrometer to measure the outgassing
species and the in-situ ellipsometer to measure thecarbon growth on a witness plate during the EUV
exposure. This system can handle a resist/wafer
size of 8 inches and a witness diameter of 1 inch.
On a resist coated wafer, the exposure area size isapproximately 2 mm (H) and 4 mm (V), and theexposure using a total power of in-band EUV light(300 mW/cm2) that is as high as that required forhigh-volume manufacturing (>100 mW/cm2). The
measured spot size of the in-situ visible lightellispometer was focused to be area size of
approximately 750 m × 750 m on a witness
sample of Mo/Si multilayers mirror to be able todetect the carbon layer thickness of 0.03 nm. In
addition, the resist/wafer and witness stages haveextremely low outgassing characteristics. Using
the rotation stage for the resist/wafer, a fresh
surface of the resist can be exposed continuously.
Using this tool, a starting time of the adhesion
point can be observed, and both the carbon
contamination layer thickness and the outgassing
species can be was evaluated during the resist
exposure by EUV light.

space (L/S) resist pattern by using two window(b)type(a)transmission diffraction grating(TDG) onwhich has 30 nm L/S grating pattern. In addition,
28-nm-diameter-hole resist pattern had been
replicated by four window-type TDG which has
40 nm L/S grating pattern [10, 11]. The SEM
image of the replicated resist patterns of 15 nm
L/S and 28 nm hole on a silicon wafer are shownin Fig. 4(a) and 4(b), respectively [12, 13].
The reduction of the vibration amplitude froma dry pump is a significant factor for the resist
patterning of a small feature size in the EUV-IL
exposure. The displacement of the vibration
amplitude between the transmission diffraction
grating and the wafer should be reduced toapproximately 1/3 of the target resolution of 10
nm in EUV-IL [14]. In order to reduce thevibration, the high-rigidity trestle and lowvibration-dry-pumping system are employedadapted to the EUV-IL exposure chamber, and therelative-vibration amplitude suppressed to be lessthan 1 nm which is enough for the 10 nm
patterning. In addition, 20 nm hp TDG has been
fabricated using organic developer instead of
2.38%TMAH to change positive-tone to negative
tone of the chemical amplified resist and adopted
using dry development rinse (DDR) process [15].
As the results, it is now ready to evaluate theresolution of 10 nm using EUV-IL at
NewSUBARU.
(a)

(b)

Fig. 4. The replicated a) 15 nm line and space andb) 28 nm hole pattern replicated by EUV
interference lithographic exposure tool.
Resist outgassing evaluation tool
The Mo/Si multilayers used as imaging optics
and a mask can be contaminated by carbon, which
is originally an outgassing species of thehydrocarbons that decompose from the resist
materials during EUV exposure. This carbon
contamination reduces the total reflectivity of theimaging optics and mask, and affects thelithographic
performance,
includingthe43

have same value at 108 nm thickness. This error
was due to the inappropriate optical structuralmodel of the photodiode which has unknown
layer structures. The values of the absorption
coefficient obtained from the four film
thicknesses measured by XRR are all within themeasurement error range. As a result, theabsorption coefficient was measured accurately
with combining the photodiode substrate and
XRR thickness measurement method. Since theerror bar was minimized with the thickest resist
sample, the sample resist thickness should bethick for accurate absorption evaluation in thephotodiode method. The calculated absorption
coefficient of this resist takes in account of theresist composition and the density of 1.3 g/cm2
was approximately 4.6 and this value is quite
different of our result of 3.8. As the results. theaccurate measurement of EUV resist absorption
coefficients using the method with combining thephotodiode substrate and XRR thickness
measurement were achieved.

Fig. 5. Photographs of the resist outgassing
evaluation tool which can measure the carbon
growth on a Mo/Si MLs mirror surface using
visible light in-situ ellipsometry.
Transmission measurement of EUV resist
Since the resist thickness in EUV lithographyof which base material mainly consists of anorganic material is thin, the EUV photon energy
is not be used efficiently for the EUV chemical
reaction. In order to increase the EUV photon
energy chemical reaction efficiently, a resist
having a high-absorption material compounds for
the EUV photons has been developed. It has beenstudied to increase the absorption including highabsorption materials such as hafnium and zinc, tinoxide, tellurium. For the development of the nextgeneration highly sensitive resist materials, since
it is significant to measure the EUV absorption
coefficient accurately, it is necessary to measure
the transmittance and resist thickness to obtain theabsorption coefficient accurately. Thus, we havedeveloped to evaluate the absorption coefficientof the EUV resist at BL10 beamline of
NewSUBARU synchrotron light facility. In theprevious paper [16], we measured the EUV resist
transmittance on a freestanding membrane.
However, since it was very difficult to coat resist
on a membrane with high uniformity, thetransmittance could not be measured accurately.
Thus, we have developed the precisetransmittance measurement method by coating
resist on a photodiode directly [17], and the resist
thickness on a photodiode was measured by XRR
accurately instead on conventional method.
Figure 6 shows the absorption coefficientcomputed with the transmittance and thickness
measurement results by both NanoSpec6100 and
XRR methods. The error bar indicates the 1%
transmittance measurement error. The absorption
coefficient using NanoSpec6100 result did not

Fig.6. Absorption coefficient computation resultsin two methods of resist thickness measurement.
EUV resist chemical reaction analysis using
soft X-ray absorption spectroscopy
The EUV resist technical issue is to achieve thehigh resolution, high sensitivity, low line-edgeroughness (LWR), and low outgassing. Since
there is a trade-off relationship between the
resolution,
sensitivity,
and
LWR,
the
simultaneous achievement of the requirement has
a difficulty. In this situation, the high sensitivity
achievement has the highest priority, because themost significant issue of the EUV lithography isthe achievement of the high power EUV source to44resist which require for high volume
manufacturing, all the chemical reaction should
be taken in account, such as the ionization and the
direct excitation reactions, as shown in Fig.9.
Increasing the sensitivity, it might have more
space to achieve the low LWR resist [21].

maintain the wafer throughput for HVM. If thehighly sensitive EUV resist will achieve, it might
be relaxing the requirement of the power of the
EUV light source. In order to achieve highsensitivity of the EUV resist, the chemical
reaction analysis using real EUV light issignificant. In general, the content of thephotosensitizing agent such as a photoacid
generator (PAG) in the EUV chemically
amplified resist material is approximately from 10
to 15% of the base resin. To analysis of the cation
and anion of PAG, the conventional analysis
methods such as XPS, FT-IR, and Raman
spectroscopy have not enough sensitivity for the
analysis of the chemical reaction analysis of the
EUV resist. Thus, we applied x-ray absorption
fine structure (XAFS) method for the chemical
reaction analysis of the EUV resist material. In
this method, the total electron yield method isused for the analysis of the chemical reaction,
because this method is very sensitive even if thecontent of PAG is small. Since it is found that thedecomposition reaction of the fluorine which
consist of the onium salts employed as a PAG is
significant in the previous study [19-21], we
increase the detection sensitivity in the TEY
method by refinement of the monochromator at
the BL10 beamline. The W/Si aperiodic
multilayer coated grating is employed for the
monochromator to extend the photon energy
region from 500 to 1100 eV as shown in Fig. 7[22]. As the results, the absorption peak signal of
the fluorine 1s core level can be measured clearly
as shown in Fig. 8. As the results of the TEYXAFS analysis applied to the EUV CA resist, it isfound that to satisfy the specification of the EUV

Fig.8. TEY-XAFS measurement result of theresist at fluorine absorption edge(a) Ph3S+X-

Ph2S + Ph + X-

Ph2S + PhH + H+X- (for PAG)(b) X-hH + + X 1- + H + + X 2- + N 1
orh
X - H + + X 3- + N 2 + N 3

Fig.9. (a) The decomposition reaction by thesecondary electron generated from the ionization
reaction and (b) the decomposition reaction of theanion of PAG by the direct excitation reaction
under EUV irradiation.
Conclusions
EUV (extreme ultraviolet) lithography is next
generation lithography for the fabrication ofsemiconductor electronic devices in 10 nm nodeand beyond. The Center for EUVL of Universityof Hyogo plays the important role to contribute toprogress the technology of resist and mask in
EUV lithography. This paper only focused on theresist research and development. The researchgroup which was involved in many national
EUVL projects in Japan to process the researchand development of EUV lithographic technology
including resist and mask technologies incollaborating with many research institutes,
companies, and university in worldwide.

Fig.7. Refectivity comparison of the wideband
W/Si-multilayer, the Ni single-layer, the Pt
single-layer samples

45

11. Fukushima Y., Yamaguchi Y., Iguchi T.,
Urayama T., Harada T., Watanabe T., andKinoshita H. Microelectric Engineering 2011,
88, 1944-1947.
12. Urayama T., Watanabe T., Yamaguchi Y.,
Matsuda N., Fukushima Y., Iguchi T., HaradaT., Kinoshita H. J. Photopolym. Sci. Technol.
2011, 24, 153-157.
13. Tanino H., Fukui T., Emura K., Hayashi Y.,
Fukuda Y., Kuki M., Yamaguchi M, HaradaT., Watanabe T., Kinoshita H., I. E. E. Jpn.
2014, 7.
14. Fukui T., Tanino H., Fukuda Y., Watanabe T.,
Kinoshita H., and Harada T. J. Photopolym.
Sci. Technol. 2015, 28, 525-529.
15. Yoshifuji M, Niihara S., Harada T., and
Watanabe T. J. Photopolym. Sci. Technol.
2018, 31, 215-210.
16. Ohnishi R., Watanabe T., Fukushima Y.,
Osugi M., and Kinoshita H. Jpn. J. Appl. Phys.
2009, 48, 06FA08.
17. Mamezaki D., Watanabe M., Harada T.,
Watanabe W. J. Photopolym. Sci. Technol.
2016, 29, 749-752.
18. S. Niihara S., D. Mamezaki D., M. WatanabeM., T. Harada T. , and T. Watanabe T. J.
Photopolym. Sci. Technol. 2017, 30, 87-.93.
19. Watanabe T., Haruyama Y., Shiono D.,
Emura K., Urayama T., Harada T., andKinoshita H. J. Photopolymer Sci. Technol.
2012, 25, 569-574.
20. Watanabe T., Emura K., Shiono D.,
Haruyama Y., Muramatsu Y., Ohmori K.,
Sato K., Harada T., and Kinoshita H. J.
Photopolym. Sci. Technol. 2013, 26, 635-641.
21. Emura K., Watanabe T., Yamaguchi M.,
Tanino H., Fukui T., Shiono D., Haruyama Y.,
Muramatsu Y., Ohmori K., Sato K., HaradaT., and Kinoshita H. J. Photopolym. Sci.
Technol. 2014, 27 631-638.
22. Kuki M., Uemura T., Yamaguchi M., HaradaT., Watanabe T., Muramatsu Y., andKinoshita H., J. Photopolym. Sci. Technol.
2015, 28, 531

Reference
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Haruyama Y., Hattori T., Kanda K.,
Kinoshita H., Matsui S., Mekaru H.,
Miyamoto S., Mochizuki T., Niibe M., Shoji
Y., Utsumi Y., Watanabe T., and Tsubakino
H. Trans. Mater. Res. Soc. Jpn. 2001, 26
783-.786.
2. Murakami K., Oshino T., Kinoshita H.,
Watanabe T., M. Niibe M., M. Ito M., H.
Oizumi H. and H. Yamanashi H. J.
Photopolym. Sci. Technol. 1998, 11, 565-570.
3. Watanabe T., Mashima K., Niibe M., andKinoshita H. Jpn. J. Appl. Phys. 1997, 36(12B), 7597-7600.
4. Watanabe T., Kinoshita H., Nii H., Li Y.,
Hamamoto K., Oshinio T., Sugisaki K.,
Murakami K., Irie S., Shirayone S., Gomei Y.,
and Okazaki S. J. Vac. Sci. Technol. 2000,
B18,.2905-2910.
5. Watanabe T., Fukushima Y., Shiotani H.,
Hayakawa M., Ogi S., Endo Y., Yamanaka T.,
Yusa S., and Kinoshita H. J. Photopolym. Sci.
Technol., 2006, 19, 521-524.
6. Fukushima Y., Watanabe T., Ohnishi R.,
Kinoshita H., Shiotani H., Suzuki S.,
Hayakawa M.,Endo Y., Yamanaka T., andYusa S. J. Photopolym. Sci. Technol. 2007,
20, 419-422.
7. Fukushima Y., Watanabe T., Ohnishi R.,
Shiotani H., Suzuki S., Hayakawa M., EndoY., Yamanaka T., Yusa S., and Kinoshita H.
Jpn. J. Appl. Phys. 2008, 47, 6293-6296.
8. Nakahara T., Watanabe T., Kinoshita H,
Mochizuki T., Takahara Y., Uozumi Y., andNakagawa K. Jpn. J. Appl. Phys.
2009, .06FC10.
9. Solak H. H., David C., Gobrecht J.,
Golovkina V., Cerrina F., Kim S. O., Nealey
P. F. Microelectronic Engineering 2003, 67,
56-64.
10. Yamaguchi Y., Fukushima Y., Iguchi T.,
Kinoshita H., Harada T. and Watanabe T. J.
Photopolym. Sci. Technol. 2010, 23 681-686.

46

Diffraction Efficiency Measurement of a Transmission
Grating for 10-nm EUV Resist Evaluation
Mana Yoshifuji, Shota Niihara, Tetsuo Harada, and Takeo Watanabe
Center for EUV lithography, LASTI, University of Hyogo

Abstract

We have developed the EUV interference lithographic exposure tool at BL-9 beamline to evaluate
the resist patterning performance. The transmission grating is a key component in the EUV
interference lithography (EUV-IL), which generate EUV interference pattern. To replicate 10 nm
line-and-space (L/S) resist pattern on a wafer, 20 nm L/S pattern is required for the transmission
grating. The pitch size of the interference fringes is a half size of the absorber pattern of thetransmission grating. We fabricated very high-aspect-ratio grating made from spin-on-carbon
material using the dry development process. EUV diffraction efficiencies of the fabricated gratingwere measured at BL-10 beamline. The measured EUV diffraction efficiencies are 14%, 11%, and
4% for 40 nm, 30 nm, and 20 nm L/S pattern grating, respectively. Using this grating, 20 nm, 15
nm, and 10 nm resist pattern could be replicated on a resist.

Introduction
EUV lithography is a lithographic
technology for the manufacturing ofsemiconductor electronic devices, and it isused for high volume manufacturing of logic
device. In addition, a patterning technology of
5 nm node which corresponds to 10-nm half
pitch is required in 2024, which requirement
was listed in the international roadmap fordevices and systems (IRDS2017)1). There areseveral issues for high-volume manufacturingof semiconductor-device fabrication in EUV
lithography. One of the critical technicalissues in EUV lithography is the developmentof EUV resist which should have the highresolution, the high sensitivity, the low
line-width roughness, and low outgassing
simultaneously. Thus, the EUV interference
lithographic exposure tool had been installedat the BL-9 beamline which had employed the10.8-m-long undulator of the NewSUBARU
synchrotron light facility2) as a light source.

EUV-IL system can generate EUV
interference fringes to replicate theline-and-space (L/S) resist pattern on a wafer
without any optical aberrations, because thesefringes were generated by the two-beaminterference from a transmission diffraction
grating. In addition, the pattern has highoptical contrast due to very low flare. In thecase of the EUV exposure system which
employs the imaging optics such as reflection
type mirrors, the flare degrades the lightcontrast of the resist pattern. The fringe-pitch
size generated on a resist in EUV-IL is a
half-pitch size of the diffraction grating,which is not depended on the exposure
wavelength.
Thus,toreplicate
10-nm-L/S-resist pattern on a wafer, thediffraction grating with 20-nm L/S pattern isrequired to fabricate.
In our previous work, the 15-nm L/S resist
pattern was generated on a wafer using the
30-nm-L/S-diffraction
grating3,4).
TaN
material
was
employedasthegrating-absorber material, which had both thehigh diffraction efficiency and nano-patternreplication property. Required diffraction
efficiency in the IL system is more than 5%.
The calculated diffraction efficiency of the
30-nm-thick TaN grating is approximately 7%.
However, the fabrication of the TaN grating
was difficult due to etching difficulty. Thus,
we applied spin-on-carbon (SOC) material to
the grating absorber.5) The calculateddiffraction efficiency of the SOC grating with

Fig. 1 Schematic drawing of EUV-IL system.
Fringe pattern is generated by the two-beaminterference of the diffraction light.
The principal of the EUV interference
lithography (IL) is shown in Fig. 1. The

47

90-nm-thick is 6% shown in Fig. 2. A
dry-development-rinse (DDR) process wasapplied to fabricate the SOC diffraction
grating pattern with high aspect ratio. The
20-nm L/S SOC diffraction grating with thehigh-aspect ratio of 5.9 was fabricated shownin Fig. 3. This report focuses on themeasurement of the diffraction efficiency offabricated SOC diffraction grating.
0.16

Diffraction effciency

Fig. 4 Photograph of the diffraction efficiency
measurement setup.

absorber material

0.14

TaN
Cr
C

0.12
0.10

EUV light was exposed to the sample gratingsfrom right side to left side. The wavelength
resolution of λ/Δλ is approximately 1,300 at the
EUV wavelength of 13.5 nm. The beam size is 5
mm in horizontal and 15 mm in verticaldirections, which was cut by the 4-mm-diameter
pinhole. The beamline focal point is at the
distance of 2.1 m upstream from the sample.
Thus, the incident beam is almost parallel. The
higher diffraction-order light generated from themonochromator was completely reduced by areflection-type high-order-cut filter using two Mo
mirrors at the grazing incidence angle of 15°.
In-vacuum CCD camera (MTE-2048B, Princeton
instruments) was located just after the sample.
The distance from the sample to the CCD image
sensor was approximately 14 mm. The active
area size of this CCD was 27.8 mm × 27.8 mm.
The acceptance angle of the CCD camera wasapproximately 45°. We measured CCD image
with and without samples. With the sample, thediffractions from the samples were recorded by
the CCD image.
The diffraction efficiency ε of +1st orderdiffraction without considering the absorption of
the Si3N4 membrane was calculated by thefollowing Eq. 1.

0.08
0.06
0.04
0.02
0.00
0

10

20

30

40 50 60 70
Thickness (nm)80

90 100 110

Fig. 2. The diffraction efficiency of atransmission grating with TaN, Cr, and carbon
materials at EUV region.

Fig. 3 Cross-sectional SEM image of the
20-nm L/S SOC grating pattern which hasquite high aspect ratio of 5.9.

εExperiments and Results
The diffraction efficiency of the fabricatedtransmission grating was measured at BL-10
beamline. A photograph of the measurement
setup are shown in Fig. 4. At the end stations of
this beamline, the measurements of thereflectivity of EUV optics and soft X-ray
scattering from the polymer sample are carriedout usually.

=(1)

Where TSi3N4, I0, and ID+1 show the calculatedtransmittance of Si3N4 layer, the intensity of theincident EUV light, and the diffraction intensityof +1st order, respectively. The calculatedtransmittance of the Si3N4 material was 45.8%
for the 91-nm thick Si3N4 membrane. This
thickness was measured by x-ray reflectivity of48

Fig. 5 CCD camera image of EUV diffraction measurements for 20-nm, 30-nm, and40-nm L/S diffraction gratings. +1st and –1st order diffractions were recorded.
At large-pitch-size gratings of 30-nm and40-nm L/S, the diffraction efficiency were quite
higher than the calculation value of 6% as shownin Fig. 2. In this calculation, pure carbon material
with a density of 1.2 g/cm3 is used for the grating
material such as SOC. Since the SOC material
will not be pure carbon, the actual diffraction
efficiency might be higher than the calculation.
Thus, we measured the actual optical index of the
SOC and the DDR material using reflection
measurement. The angular reflection spectra areshown in Fig. 6, which were measured at thesame BL-10 beamline. The SOC and DDRmaterials are coated on the Si wafer under thesame condition. The analyzed optical index of the
SOC and DDR material are n: 0.9777 and k:
0.0038, and n: 0.980 and k: 0.0074, respectively.
The calculated diffraction efficiency on a basis ofthese actual optical index are 11%. The residual
difference might be caused by the difference of
the actual Si3N4-layer thickness, or the differenceof its optical index in the transmission calculation
by Eq. 1.
The EUV diffraction efficiencies of thefabricated gratings were measured to be 14%,11%, and 4% for 40 nm, 30 nm, and 20 nm
L/S pattern grating, respectively. Using thesegratings, 20 nm, 15 nm, and 10 nm resist
pattern might be replicated on a resist. And it
was found that it has sufficient diffraction
efficiency for interferometric exposure usingsynchrotron radiation.
We will evaluate the 10-nm-L/S-patterning
performance of the EUV resists using thishigh-aspect-ratio grating adapted to the
EUV-IL system in near future. This
high-aspect-pattern-fabrication process canalso be applied for the fabrication process of
Fresnel-zone plate (FZP) for the usage in thesoft x-ray region. A metal-absorber FZP could
be fabricated using this high-aspect organic

the Si3N4 wafer.
Fig. 5 shows the diffraction image of a grating
which was recorded by the CCD camera. The
intensity scale shows the transmittance. In thecenter region of 0th order diffraction, theintensity is shown in 1/10 scale in comparison
with the other weak diffractions, and the square
membrane and 0th order diffraction are observed
and recorded. There were -1st and +1st orderdiffractions at bothside. The diffraction angle
depends on the pattern size. The patterns sizes ofthe diffractions are 20 nm, 30 nm, and 40 nm L/S
grating from the top to bottom. As the results, thediffraction efficiency of the 20-nm L/S
SOC-pattern was approximately 4.4% for thegrating. This diffraction efficiency of 4.4% is
acceptable for the EUV-IL system to replicate the
10-nm resist pattern on a wafer. Those of 30 and
40 nm L/S pattern were 10 and 14% for thegrating, respectively. These high diffraction
efficiencies were very effective for the EUV-IL
system to replicate resist pattern on a wafer.

Fig. 6 Measurement result of EUV angularreflection spectra of the SOC and the DDRmaterial coated on a Si wafer.

49

pattern, where the expected metal thickness
was over 50 nm. Especially in soft-x-ray
region, such metal structure will have highdiffraction efficiency.
References
1. International Roadmap for Devices andSystems (IRDS) 2017 [https://irds.ieee.org/].
2. Y. Fukushima, N. Sakagami, T. Kimura, Y.
Kamaji, T. Iguchi, Y. Yamaguchi, M. Tada, T.
Harada, T. Watanabe, and H. Kinoshita; Jpn. J.
Appl. Phys., 49 (2010) 06GD06.
3. Y. Yamaguchi, Y. Fukushima, T. Harada, T.
Watanabe, and H. Kinoshita; Jpn. J. Appl.
Phys., 50 (2011) 06GB10.
4. T. Urayama, T. Watanabe, Y. Yamaguchi, N.
Matsuda, Y. Fukushima, T. Iguchi, T. Harada,and H. Kinoshita; J. Photopolym. Sci. Technol.,
24 (2011) 153.
5. M. Yoshifuji, S. Niihara, T. Harada and T.
Watanabe; J. Phtopolym. Sci. Technol., 31(2018) 251.

50

Deterioration Analyses of CFRP Surface
Hideo Kobayashi1, Yosuke Azuma1, Shogo Suehiro1,
Sohta Hamanaka2, Yuki Tobita2, Takuya Motokawa2, and Yasuji Muramatsu2
1

Sumika Chemical Analysis Service, Ltd.,2 Graduate School of Engineering, University of Hyogo,

Abstract
We conducted the deterioration analyses of CFRP by using soft X-ray absorption
spectroscopy at BL10 / NewSUBARU. In this report, we discuss the change in the surface
condition due to heat treatment.
Introduction
Carbon fiber reinforced plastics (CFRP) is
widely used in many products, such as airplanes
and mechanical parts. CFRP composite materials
have excellent mechanical characteristics such as
specific strength, specific stiffness, and corrosion
resistance.
Evaluation of the degradation
properties of CFRP is necessary and important toenhance its reliability.
The purpose of this study is to analyze heat
treatment effect for CFRP by using soft X-ray
absorption spectroscopy (XAS) with total electron
yield (TEY) method at BL10 / NewSUBARU.

of heating.
Figure 4 shows the orientation angle of C=O
bond by OK-XANES. The angle between theperpendicular π* orbital to the substrate surface
was calculated
and the molecular plane
according to the method of previous study[1]. We
judged the orientation random if the orientation
angle is around 54.7°.
The orientation angle decreased at 0.5h, andthat increased and became random structure as theheating time increased. It is speculated that the
C=O orientation was detected at the beginning ofheating, however the melting of polymer and theexposure of carbon fiber made C=O orientation
random.

Experiments
CFRP was heated at 200 °C for 0.5 h, 4 h, 8 h,
24 h and 48 h. After heat treatment, CFRP was
cut about 20 mm × 10 mm.
XAS measurement was performed acrosscarbon K-edge, nitrogen K-edge and oxygen
K-edge (CK, NK and OK) with TEY method.
The incident angle of soft X-ray was tuned to 90°,54.5° and 30°.
All XANES spectra werenormalized at σ* peaks at 290 – 295 eV in
CK-edge and 537 – 541 eV in OK-edge.

Figure 5 shows the intensity ratio Oσ* / Cσ* of
CFRP for heating time. Oσ* is a σ* peakintensity of OK-XANES and Cσ* is that of
CK-XANES before normalization.
The intensity ratio gradually increased in 8 h orless although that increased sharply after 8 h. It is
probable that the oxidization behavior of XANES
spectra was due to a functional group of theoxidized polymer and that of the exposed carbon
fiber. XAS measurement for a carbon fiber alone
and a polymer alone also need to be examined infuture studies.

Results and Discussion
Figure 1 shows microscope images of CFRP
surface. The CFRP surfaces of 0 h, 0.5 h, 4 h and
8 h look smooth and those of 24 h and 48 h lookrough. This is because the polymer of CFRP was
melted and carbon fiber was exposed.

Reference[1] F. Zheng, B. N. Park, S. Seo, P. G. Evans, F. J.
Himpsel: J. Chem. Phys., 126, 154702 (2007).

Figure 2 and 3 show X-ray absorption
near-edge structure (XANES) spectra for CK-edge
and OK-edge of CFRP. The incident angle ofsoft X-ray was 54.5°.
Peak intensities of 285.5 eV and 288.0 eV in
CK-XANES, and 532.5 eV in OK-XANES
obviously changed depending on heating time. In
addition, the subtle difference could be observed in
0.5 h for heating. This difference could not be
observed by microscope. Those peak intensities
indicate that the melting of polymer and theexposure of carbon fiber began from the beginning

51

Orientation angle / °

60
55
50
45
40
35

0

20

40

Heating time / hFigure 4. Orientation angles of C=O bond forheating time.
0.6
0.5
O σ* / C σ*

Normalized intensity / a.u.

Figure 1. Microscope images of CFRP surface.

1

0

0.3
0.2

0h
0.5h
4h
8h
24h
48h

280

285

290

295

0.1

0

300

0h
0.5h
4h
8h
24h
48h

520

20

40

Figure 5. Intensity ratio Oσ* / Cσ* for heatingtime.

Figure 2. CK-XANES spectra of CFRP.

1

0

Heating time / h

Photon energy / eV

Normalized intensity / a.u.

0.4

540
560
Photon energy / eV

Figure 3. OK-XANES spectra of CFRP.

52

Soft X-ray absorption measurements of self-standing
polyethylene thin films using a transmission method
Yuya Matsumoto and Yasuji Muramatsu
Graduate School of Engineering, University of Hyogo
Abstract
To experimentally determine the mass absorption coefficient (μ) in soft X-ray regions of sp3
carbon atoms, we have measured X-ray absorption spectra of polyethylene (PE) thin films
using a transmission mode in BL10/NewSUBARU. Thickness of the measured PE films were
1.4 ~ 2.8 μm. Measured μ spectra in the 400~600 eV region were approximately agree to thetheoretical spectrum. However, the measured μ spectra in CK region were smaller than thetheoretical spectrum. This shows that the measured PE films were too thick to correctly
measure μ in CK region.
1. Introduction
To determine the mass absorption coefficient(µ) from X-ray absorption measurements, atransmission method should be basically usedaccording to the Lambert-Beer's law. However, insoft X-ray region, the value of µ is generally solarge that self-standing thin samples should be
prepared and it is experimentally hard to performthetransmission
method.
Therefore,atotal-electron-yield (TEY) method is often used insoft X-ray absorption measurements.
Recently we have tried to determine the µ of
sp2-carbon atoms by using ultra-thin graphite films[1]. In the next step, we are trying to determine theµ of sp3-carbon atoms. The most typical material
consisting of sp3-carbon is diamond. Transmission
length in CK region of diamond (density, ρ=3.5 gcm-3) is estimated to be less than 50 nm. However,
it is difficult to get such the self-standing ultra-thindiamond films. Hence, we have focused onpolyethylene (PE) films, because its low density (ρ< 1 g cm-3) and longer transmission length in CK
region. Figure 1 shows the calculated transmission
length of PE in soft X-ray region. The calculations
were performed with the on-line system of theCenter for X-Ray Optics (CXRO) [2,3]. The 200
nm-thick PE sufficiently transmits X-rays in CK
region, and 1 µm-thick PE transmit ~500 eV
X-rays. This means that µ in soft X-ray region canbe experimentally determined by using 200 nm ~ 1µm-thick PE films with a transmission mode.

In the present study, as the first attempt, wehave measured soft X-ray absorption spectra of 1.4~ 2.8 µm-thick PE films.

Fig. 1 Calculated transmission length in the 200~ 800 eV region of polyethylene film.

2. Experiments
Linear-low-density PE thin films (thickness :2.8 μm, density: 0.920 g cm- ) were supplied from
Shibataya Kakoshi Co., Ltd. The 2.8-μm thick PE
film was manually stretched to the thickness of 1.4
μm and 1.7 μm. These self-standing 1.4 ~ 2.8
μm-thick PE films were placed on an Al substrate
which opened 3mmH x 5mmW window, and held atboth edges of the window frame using conductive
carbon tapes, as shown in Figure 2.
Soft X-ray absorption measurements of thePE films were performed in the XRR (X-ray
reflectivity) chamber at the BL10/NewSUBARU.

53

Intensity of transmitted X-rays through the PE
films were measured with a photodiode detector.
TEY spectra of the PE films were measured bymonitoring sample current through the Al substrateduring soft X-ray irradiation onto the PE film
adhered to the carbon tape.

Fig. 2 Photo of PE film put on an Al substrate.

3. Results and Discssion
Measured transmittance, absorbance and μ in
the 200 ~ 600 eV region of the PE films are shownin Figure 3. Transmittance and absorbance variedsystematically with film thickness and showed areasonable trend. CK edge can clearly observed
near 280 eV both in the transmittance andabsorption. The μ spectra were converted fromabsorbance spectra with a standard density of
0.920 g cm-3 and film thickness. Calculated μspectrum is described on the measured μ spectra.
In the 400 ~ 600 eV region, the measured μ spectra
are in good agreement to the calculated spectrum.
This is almost consistent with the transmission
length shown in Figure 1, and it is considered thatthe μ spectra of PE can be correctly measured.
However, in the CK-edge ~ 400 eV region, themeasured μ spectra are significantly lower than thecalculated μ, because the measured PE thickness is
too thick to measure μ in the region. Actually,CK-XANES measured with a transmission mode
(i.e. absorbance) were different from that with a
TEY mode. This confirms that the 1.4 ~ 2.8
μm-thick PE films was too thick to measure μ in
CK region.
We are now preparing to make thinner PE
films with a spin-coating method.

Fig. 3 Comparisons of the soft X-ray
transmittance (a), absorbance (b), and µ (c) in
the 200 ~ 600 eV region of PE films of eachthickness.

References[1] Y. Muramatsu, Y. Soneda, and E. M. Gullikson,
The 40th International Conference on Vacuum
Ultraviolet and X-ray Physics, VUVX19,
Poster 28 (2019).
[2] http://henke.lbl.grov/optical_constants/[3] B.L. Henke, E.M. Gullikson, and J.C. Davis,
Atomic Data and Nuclear Data Tables Vol. 54,
181-342 (1993).

54

Surface structural analysis of nanodiamond by using soft
X-ray absorption spectroscopy and the first principle
calculations
Tatsuki Maeda and Yasuji Muramatsu
Graduate School of Engineering, University of Hyogo
Abstract
To clarify the surface structure of nanodiamond, soft X-ray absorption spectra of various detonation
nanodiamond (DND) samples were measured in BL10 / NewSUBARU. CK-XANES of DND weretheoretically analyzed by using the first principle calculation package of CASTP. XANES analyses
suggest that surface of DND particles can be covered with sp2 carbon atoms forming polycyclic hexagonal
and/or pentagonal rings.
calculations were performed. Then, excited-statecalculations were carried out by providing corehole in the 1s orbital of the target atom.
Transition energy was corrected by the
Mizoguchi method [3].

1. Introduction
Nanodiamonds have attracted muchattention as functional materials because of their
excellent mechanical and electrical properties. To
develop the excellent functional nanodiamonds,
surface structural analysis is important, because
surface effect should become significant in the
nano-scale particles.
Soft X-ray absorption spectroscopy (XAS)
is a powerful tool for characterization of low-Zmaterials. Especially, XAS with a total-electronyield (TEY) method easily provides electronic
structure information on quasi-surface ofmaterials. Local structure can be clarified fromthe XAS analysis using the first principle
calculations.
In this study, to clarify the surface structureof nanodiamond, we have measured XAS spectraof various DND samples and theoreticallyanalyzed the spectra.

3. Results and Discussion
Fig.1 shows the CK-XANES of the DND
samples with a reference HOPG. XANES of
DND samples exhibit the similar profile ofdiamond. However, each DND sample exhibits

2. Experiments and calculations
Sixteen DND powder samples wereprepared by Daicel Corporation. Depending on
the detonation conditions, the samples werelabelled as NDD1 ~ 3, NDA1 ~ 7, and ND1 ~ 6.
These samples were held on indium substrate for
XAS measurements. XAS measurements
including CK- and OK-XANES were performedin the analysis chamber at BL10/NewSUBARU[1] using a total-electron-yield (TEY) method.
Theoretical XANES analysis was
performed by using the first-principle calculation
package of CASTEP [2]. Appropriate
nanodiamond cluster was put in the center of asupercell. In order to suppress intermolecularinteraction, the distance between the supercell
boundaries and the model was set to longer than
5 Å. After the structure optimization by theMaterial
Studiopackage,ground-stateFig. 1 CK-XANES (a) of nanodiamond samples
with a reference HOPG. Right panel (b) showsthe enlarged spectra in the 280 – 287 eV region.

55

XANES of proposed bucky diamond model byusing CASTEP. Figure 2 shows a calculation
model (C147H28) and calculated CK-XANES ofthe focusing carbon atoms labelled as C1~C7 in
the figure, comparing to the measured CKXANES of NDD1. This calculation model has adiamond core cluster consisting of sp3 carbon
atoms and is covered with polycyclic hexagonal
and/or pentagonal rings consisting of sp2 carbon,
which is called as bucky nanodiamond. The σ*peak of the calculated XANES was adjusted tothe σ* peak energy position in the measured
XANES. In the calculated XANES of sp2-carbon
atoms, small peaks are observed in the lowerenergy position from the σ* peak. Such thelower-energy peaks of surface sp2-carbon atoms
result in the measured small π* peaks. However,
the measured peaks cannot be completely
reproduced by the calculated XANES. Other
surface structures including oxidized structures
should be considered to assign them. Actually,
OK-XANES was clearly observed in the DND
samples.
XANES calculations of surface-oxidized
bucky diamond cluster models have been inprogress.

small peaks near 285 eV corresponding to the π*
peak of HOPG. The enlarged spectra in the 280 ~287 eV region clearly shows the three structures(denoted as a ~ c) as π* peak. This indicates that
DND includes slightly sp2 carbon atoms, which
agrees to the previous studies on bucky diamonds[4].
To clarify the local structure of DND
having sp2 carbon atoms, we have calculated CK-

Reference[1] Y. Muramatsu, A. Tsueda, T. Uemura, K.
Nambu, T. Ouchi, T. Harada, T. Watanabe,and H. Kinoshita, LASTI Annual Report, 17,29-30 (2015).
[2] J. Clark, M. D. Segall, C.J. Pickard, P. J. Hasnip,
M. J. Probert, K. Refson, and, M. C. Z. Payne,
Krystallogr, 220, 567-570 (2005).
[3] T. Mizoguchi, I. Tanaka, S.-P. Gao, and C. J.
Pickard, J. Phys. Condens. Matter, 21,104204(2009).
[4] J.-Y. Raty, G. Galli, C. Bostedt, T. W. van
Buuren, and L. J. Terminello, Phys. Rev.
Lett. 90, 037401 (2003)

Fig. 2 Calculated CK-XANES of surface carbon
atoms in the bucky diamond model (C147H28),
compared to the measured CK-XANES of NDD1.

56

Direct detection of PM2.5 collected on insulating
membrane filters using a total-electron-yield soft X-ray
absorption spectroscopy
Takuya Motokawa and Yasuji Muramatsu
Graduate School of Engineering, University of Hyogo
Abstract
We have proposed a new method for direct detection of particulate matter (PM) 2.5 collected on membranefilters by using a total-electron-yield (TEY) soft X-ray absorption spectroscopy. TEY-XANES of the PM2.5
sample on insulating membrane filters can be successfully measured in BL10/NewSUBARU. Comparing to
XANES of reference compounds, chemical state analysis of PM2.5 can be easily performed by the TEYXANES measurements.
1. Introduction
We have recently developed a new method
for total-electron-yield (TEY) measurements ofinsulating bulk samples [1, 2]. In this method,
insulating film samples, whose thickness is lessthan 100 μm, are put on conductive substrates.
Sample current of the film samples can be
sufficiently detected through the substrate,during soft X-ray irradiation onto the samples.
Such the TEY method enables to easily measure
X-ray absorption near-edge structure (XANES)of insulating materials.
To utilize this method for chemical
analysis of insulating materials, we havemeasured XANES of particulate matter (PM) 2.5
collected on insulating membrane filters.

intensity (I0) was monitored with sample currentof a clean gold (Au) plate. Then, TEY can beobtained as the sample current (I) divided with I0.

2. Experiments
Figure 1 shows membrane filters (blank)
and PM2.5 collected on the filters. The PM2.5
samples were collected at the Hyogo Prefectural
Environmental Research Center in Kobe on June,
2017. Two kinds of commercially available
membrane filters were used; one is PM 2.5 airmonitoring PTFE membrane filter (Whatman)labeled as WFT and another is KFT-730 (Kimoto
Electric) labeled as KFT. PM2.5 were collectedwith high concentration (labeled as HPM) andwith medium concentration (MPM) on eachmembrane filter. Thus, PM2.5 samples arelabelled as HPM/WFT, MPM/WFT, HPM/KFT,
and MPM/KFT. The filter samples were cut into
5 mm square and held on a conductive carbon
tape on an aluminum sample plate. Sample
current was measured through the carbon tape.
TEY X-ray absorption measurements in
CK, OK and 200 ~ 600 eV regions of the PM2.5
samples were performed in the analysis chamberat BL10/NewSUBARU [3]. Incident soft X-ray

Fig. 1 Photo and specifications of the PM2.5
samples on membrane filters.

3. Results and Discussion
Figure 2 shows sample current spectra of
the blank filters and PM2.5 samples. Although
the measured sample current was less than 8 pA
in 200 ~ 600 eV, absorption peaks can be clearlyobserved in CK and OK edges. Figure 3 shows
the TEY X-ray absorption spectra (XAS) in the
200 ~ 600 eV region of the samples and thesubtracted spectra, (PM2.5/filter) - (blank filter).
The subtracted spectra show the spectra of PM2.5.
Each subtracted spectrum clearly shows intense
CK and OK peaks, and small NK peaks. Thismeans that PM2.5 mainly consists of carbon andoxygen with small nitrogen.
Figure 4 shows the TEY CK-XANES ofthe samples and the subtracted spectra,(PM2.5/filter) - (blank filter). Although blank
filters (WFT and KFT) exhibit no π* peak,

57

The 289 eV-peak can be assigned to sp3 carbons
forming C-C structures. It is therefore confirmedthat PM2.5 consists of sp2 carbon and sp3 carbons.
Figure 4 also shows that the subtraction,
PM2.5/filter – filter, easily provides XANES of
PM2.5.

Fig. 2 Sample current spectra in the 200 ~ 600
eV region of blank filters and PM2.5 samples.

Fig. 4 TEY CK-XANES of blank filters andPM2.5 samples. Subtracted spectra, (PM2.5
sample) - (blank filter) are also described.
.
4. Conclusion
Soft X-ray absorption spectra of PM2.5
have been successfully and directly measured byusing a TEY method. Subtracted spectra of(PM2.5/filter) – (blank filter) provide soft X-ray
spectra of PM2.5. The proposed method would
be a powerful tool for chemical analysis of
atmospheric environmental particles.
Fig. 3 TEY-XAS in the 200~600 eV region ofblank filters and PM2.5 samples. Subtracted
spectra, (PM2.5 sample) - (blank filter) arealso described.

5. Reference[1] Y. Muramatsu, The 76th Annual Meeting ofAnalytical Chemistry, Japan, F1010 (2016).
[2] Y. Muramatsu, Y. Tani, Y. Tobita, S.
Hamanaka, and E. M. Gullikson, Adv. X-Ray
Chem. Anal. Japan, 49, 219-230 (2018).
[3] Y. Muramatsu, A. Tsueda, T. Uemura, K.
Nambu, T. Ouchi, T. Harada, T. Watanabe,and H. Kinoshita, LASTI Annual Report, 17,29-30 (2015).

PM2.5/filter samples exhibit π* peak near 285 eV
and peak near 289 eV. Subtracted spectra whichshould be the CK-XANES of PM2.5 clearlyshow the π* peak and 289 eV-peak. The π* peakcab be assigned to sp2 carbons forming C=C bondin aromatic or unsaturated aliphatic structures.

58

Soft X-ray spectroscopy of coal tars
Kosuke Shirai and Yasuji Muramatsu
Graduate School of Engineering, University of Hyogo
Abstract
XANES in the CK, NK, and OK regions of industrial coal tar samples were measured
BL10/NewSUBARU for chemical analysis and structural identification. From the correlation between theheight and width of π* peak in C K-XANES (i.e. π* peak map), it can be suggested that coal tar isaggregates of aromatic molecules whose ratio of edge carbon atoms is approximately 2/3 of the total
carbon. It is also confirmed that the π* peak map is useful for identification of coal tar.
amount of nitrogen and oxygen. It is also
confirmed that the minor portion of nitrogen andoxygen can be detected by the TEY method.

1.Introduction
Coal tar is considered to be aggregates ofpolycyclic aromatic hydrocarbons (PAHs) fromchromatography analysis. However, a novel
characterization technique for coal tar has beenrequired in industry, because coal tar takes toocomplicated structure to easily identify its
molecular structure.
Soft X-ray absorption spectroscopy (XAS)
using synchrotron radiation has been a powerfultool for characterization of carbon materials. We
have recently found that relationship between thewidth and height of π* peak (named as “π* peakmap”) in CK-XANES provide local structure
information of graphitic carbon materials [1].
In this study, to identify local structure ofcoal tar using soft X-ray absorption spectroscopy,
we have measured soft X-ray absorption spectraof various industrial coal tar samples and apply
the π* peak map to coal tar for identification.
2. Experiments
Industrial coal tar samples were supplied
from Japanese chemical company. The six
samples are labelled as T1 ~ T6. Samples of T1 ~T4 were thin films; T1 ~ T4 were dissolved inorganic solvents and put onto a gold (Au)
substrates. Samples of T5 and T6 were powders.
The powders were pressed and held on an indium(In) substrates. Highly oriented pyrolytic graphite(HOPG) and carbon black (CB, N660) were used
as references.
Soft X-ray absorption measurements were
performed in BL10/NewSUBARU [2] using a
total-electron-yield (TEY) method.

Fig. 1 TEY-XAS in the 200 – 600 eV region ofcoal tar samples.

Figure 2 shows the CK-XANES of coaltar samples with the reference HOPG and CB.
Subtracted spectra of (coal tar) - (HOPG) arealso described on XANES. XANES profiles ofcoal tar exhibit wider π* peak profile than thatof HOPG. Such the wider portions in π* peak ofcoal tar can be clearly shown as the peaks near284.5 eV in the subtracted spectra. The 284.5
eV-peak is labelled as peak a. This findings ofwider π* peak profile suggests that the edge
carbon atoms of PAH in coal tar can be detected.
T1 exhibits peak near 288 eV. This suggests that

3. Result and Discussion
Figure 1 shows TEY-XAS spectra in the
200 ~ 600 eV region of coal tar samples. Eachcoal tar sample exhibits mainly CK peak andsmall NK and OK peaks. This means that coaltar consisting mainly of carbon includes small

59

T1 has alkyl C-C structures consisting sp3
carbon atoms.

Fig. 3 The π* peak map of coal tar samples
with nano-graphite, carbon black, andvarious polycyclic aromatic hydrocarbons.
In conclusion, it can be elucidated that theπ* peak map obtained from the CK-XANES isuseful for structural identification of coal tar.
References[1] Y. Muramatsu, K. Murayama, and T. Okada,
Proceedings of the 10th International
Symposiumon
AtomicLevel
Characterizations for New Materials andDevices ’15, ALC'15, 27p-P-38 (2015).
[2] Y. Muramatsu, A. Tsueda, T. Uemura, K.
Nambu, T. Ouchi, T. Harada, T. Watanabe,and H. Kinoshita, LASTI Annual Report, 17,29-30 (2015).

Fig. 2 CK-XANES of coal tar samples with thereference highly HOPG and carbon black (CB).
Subtracted spectra of (CB) –(HOPG) and (Coaltar samples) – (HOPG) are described on each
XANES.
Figure 3 shows the π* peak map of coaltar samples (T1 ~ T6) with the nano-graphite [1],carbon black, and various PAHs. Coal tar
samples distribute in two groups on the π* peak
map; One is T1 on the line of nano-graphite,
another is T2 ~ T6 on the areas of middle peak aheight and higher π* peak height. Such the
distribution suggests that T1 take larger
hexagonal carbon layer structures similar tocarbon black and that T2 ~ T6 are basically PAH
molecules. Compared to the distributions of
PAH molecules, T2 ~ T6 distributes near the
PAHs in which ratio of hydrogen-terminatededge carbon atoms in molecules isapproximately 2/3. This means that the coal tar
samples should mainly consist of such the PAH
structures.

60

Controllability of copper particle synthesized by X-ray
radiolysis using synchrotron radiation
Akinobu Yamaguchi1, Ikuo Okada2, Ikuya Sakurai2, Takao Fukuoka1, and Yuichi Utsumi1
1
Laboratory of Advanced Science and Technology, University of Hyogo
2
Synchrotron Radiation Research Center, Nagoya University

Abstract

We demonstrate the synthesis and immobilization of caltrop-shaped cupric particles from theCu(CH3COO)2 solution with an additive alcohol by X-ray radiolysis using synchrotron radiation.
The particles could be synthesized in the X-ray radiolysis of aqueous solutions of Cu(CH3COO)2,
which also contain methanol, ethanol, 1-propanol, 2-propanol. We found the alkyl alcohol whose
chain length is longer than four cannot synthesize any particles. The alcohol solubility plays asignificant role in nucleation and synthesis. Our study may shed light on understanding aphotochemical reaction route induced under the X-ray irradiation.

Introduction
Conventional chemical synthesis of inorganic
materials has been developed for many
applications such as catalysis, medicine,electronics,
ceramics,
cosmetics,
andbio/molecular-sensing using surface enhanced
Raman scattering (SERS). Recently, a lot
nanoparticles and nanostructures, such as
nanowires, nanorods, nanoribbons, nanobelt,
and nano-flower have been synthesized byvarious techniques.
The photochemical reaction has a possibility toachieve a novel three dimensional (3D) printing
and additive manufacturing process because of
its easy and intriguing applicability andengineering applications. There are manytechniques which can fabricate 3D structures
made of plastic or metallic materials. However,there are few techniques which can create astructure consisting of composite materials suchas metallic, plastic, and oxidized materials, etc.
The photochemical reaction might be one of thecandidates which can fabricate the 3D structure
consisting of composite materials.
Here, we demonstrated the synthesis ofnano/micro-scale metallic, oxidized and theirclusters deposited onto a substrate by the X-ray
radiolysis-induced photochemical reaction using
Synchrotron Radiation (SR) facility. The
advantage of performing X-ray radiolysisinduced photochemical reaction using SR is its
atomic level of processing accuracy; finecontrol; deep lithography and so on. Several
groups also reported the synthesis ofnano/micro-scale particles by monochromatic
X-ray irradiation. [1, 2]
In this study, we have noticed that the additive
ethanol plays a significant role in the reduction
and synthesis of particles directly from thesolutionby
X-ray
radiolysis-induced

photochemical
reaction.
Therefore,
we
investigate the alkyl chain length dependence ofsynthesis to understand the mechanism ofparticle nucleation, ripening, and aggregation to
obtain the deeper understanding of contributionsof alcohols.
Experiments
The stock solution was made by dissolving 6.8
g of Cu(CH3COO)2 (Wako Chemical, 99.99%)
in 100 mL of doubly distilled water. We
syphoned off 200 L of the solution into a
microtube and added 10 L alky alcohols frommethanol (R-1) to 1-deconol (R-10), and 2propanol (R-2’) to obtain the mixed solution. An
18 L aliquot of the mixed solution was thenexposed to X-ray irradiation as schematicallyshown in Fig. 1. In this study, a silicon substrate
was dipped into the mixed solution and thespecimen was placed on the irradiation system.
The specimen was exposed to 5 minute X-rays
and then washed using deionized water. The
synthesized particles deposited on the silicon
substrate were examined by field emission
scanning electron microscopy with energy

Fig. 1 Experimental setup for the X-ray irradiation of theCu(CH3COO)2 solution including alky alcohol.

61dispersive X-ray spectroscopy (EDX). In
addition, we obtained Raman spectra using a
micro-Raman spectrometer to determine thematerial characteristics of the synthesizedparticles.
Results and discussion
No particles were synthesized when the silicon
substrate was immersed in an aqueous
Cu(CH3COO)2 solution including of no additive
and the following alkyl alcohols from 1-butanol
to 1-decanol. We also found no particles weresynthesized when the acetone and acetic acid
were added into the solution. As a result, wereveal that there is an upper limit of a chain
length of alkyl alcohol to synthesize the particles
in aqueous solution to be 3.
Figures 2 and 3 show typical SEM image and
EDX analyses of particles synthesized when theethanol and 1-propanol were added into thesolution, respectively. We found that thesesynthesized particles are copper oxide materials.

Fig. 4 Micro-laser Raman spectra of the particles
synthesized by the X-ray irradiation of aqueous
Cu(CH3COO)2 solution including (a) ethanol and (b) 1propanol, respectively. The insets are optical
micrographs of the particles; the position of the green
light corresponds to the measurement position of thelaser.

We show micro-laser Raman spectra to
determine the composition of the synthesizedparticles as shown in Fig. 4. There are threecandidates of copper oxides, CuO, Cu2O andCu4O3. Peaks at 283, 333, and 622 cm-1 arededuced to be Raman signals from Ag and Bg
modes of cupric oxide CuO.

Fig. 2 SEM image and EDX analyses of particles
synthesized by the 5 min. X-ray radiolysis-induced
photochemical reaction of the Cu(CH3COO)2 solution
including ethanol.

Conclusion
Our study demonstrates the synthesis of copperoxide particles deposited onto a Si substrate
under
the
X-ray
radiolysis-induced
photochemical reaction. This work also leads toadditive alcohol chain number dependence ofsynthesizing particles. This method can also
provide novel lithography process.
References[1] R. A. Rosenberg et al., J. Vac. Sci. Technol. B
16, 3535 (1998); Q. Ma et al., Appl. Phys. Lett.
76, 2014 (2000).
[2] A. Yamaguchi et al., Mater. Chem. Phys. 160,
205 (2015); Jpn. J. Appl. Phys. 55, 055502(2016); J. Nanometer. 8584304 (2016); J.
Synchrotron Radiation 24, 653 (2017); J.
Synchrotron Radiation to be published.

Fig. 3 (a) SEM image and (b) – (d) EDX analyses of (i)substrate and (ii) (iii) particles synthesized by the 5 min.
X-ray radiolysis-induced photochemical reaction of theCu(CH3COO)2 solution including 1-propanol.

62

Deposition of Polytetrafluoroethylene Film
via Synchrotron Radiation
Masaya Takeuchi, Akinobu Yamaguchi, Yuichi Utsumi
Laboratory and Advanced Science and Technology for Industry, University of Hyogo

Abstract

A novel process was developed for fabricating a polytetrafluoroethylene (PTFE) thin film usingsynchrotron radiation (SR). First, a PTFE substrate was exposed to high-energy X-rays (2–8 keV)at room temperature. Afterwards, the PTFE substrate (target) was heated under atmospheric pressureand fragments desorbed from the surface deposited on a glass substrate to produce a film with athickness of above 10 µm. The characterization of the chemical structure of the deposited film wascarried out using X-ray diffraction (XRD). The results indicated that the crystalline structure of thefilm became closer to those of the PTFE substrate upon an increase in the X-ray irradiation of thesample. The fabrication process of this PTFE thin film could be applied to various fields because
surface modification of the substrate can be easily carried out.

Introduction
Comparedwith
otherpolymers,
polytetrafluoroethylene (PTFE) has high heat
resistance, excellent chemical stability, electricalinsulation and low friction. Due to theseoutstanding properties, it is used in various
applications, such as piping tube, packing inchemical plants, and cable coating. Also, thinfilms of PTFE are required for certain
applications, such as proton exchange
membranes [1] and membranes for desalination[2].
Several methods have been reported for
fabricating thin films of PTFE, such as
thermolysis [3], ion-beam sputtering [4], laser
ablation [5-7], and synchrotron radiation (SR) [810]. These are performed by depositing
fragments derived from PTFE on a substrate.
Films deposited via SR can be speciallyfabricated with a high deposition rate, withcompositions and crystalline features similar to
those of the PTFE substrate. The method can be
performed by etching has been proposed [12,13],which is carried out by heating an X-ray
irradiated PTFE substrate. An etching depth of 1
mm can be obtained using this method.
In this study, a novel process was developed
for fabricating a PTFE thin film using SR. First,
a PTFE substrate was subjected to high-energy
X-rays (2–8 keV) at room temperature.
Afterwards, the substrate (PTFE target) was
heated under atmospheric pressure and fragments
desorbed from the surface deposited on a glass
substrate. As previously mentioned, high-energy
X-ray photons can penetrate more deeply in the
PTFE substrate to induce chain scission.
Therefore, more fragments, which desorbed fromthe surface upon the heating of the PTFE target,

are generated, significantly increasing thenumber of molecules that can form a deposited
film. The chemical structure of the film were thenevaluated using X-ray diffraction (XRD).
Experiments and Results
PTFE thin films were prepared via the SR
irradiation of PTFE substrates. The exposure wascarried out on beamline BL-11 [14] of the
NewSUBARU SR facility at the University of
Hyogo, Japan. The storage ring electron energy
was set at 1.5 GeV. Figure 1 (a) shows thecalculated spectrum of the X-ray beam at the
exposure stage, which is continuous from 2–
8 keV with a peak photon energy of 4.5 keV.
Figure 1 (b) shows the photon energy dependenceof the transmittance through PTFE substrates
with various thicknesses of 10, 20, 50, 100, and300 µm. X-rays with higher photon energy areable to penetrate deeper into the film, causing
scission of the main chain C–C bonds, induced
from the PTFE surface to a depth of around 300µm via X-ray irradiation on beamline BL-11.
A commercially available PTFE substrate(UNIVERSAL Co., Ltd., 00I-251-02) was used
to prepare the PTFE target with a thickness of
1.5 mm, which is enough to suppress the
distortion of the substrate caused by heating
during the deposition. The PTFE substrate wasplaced perpendicular to the incident X-ray beamin the exposure chamber of beamline BL-11 andvertically scanned at a scanning rate of 5 mm/s.
The X-ray irradiation dose was controlled bychanging the number of scans. Here helium (He)gas was introduced into the exposure chamber tosuppress the temperature rise of the PTFE
substrate and evaporation of the depolymerized

63

PTFE molecules during X-ray irradiation. The
PTFE target was heated under atmosphericpressure on a hot plate for 1 hour and thefragments desorbed from the substrate surface
were deposited onto a glass substrate. The air-gap
distance between the PTFE target and the glass
substrate was 3 mm. The PTFE target was used
to prepare deposited films using X-ray doses of
1.7, 3.0, and 4.3 J/mm2. The thicknesses of thedeposited films were measured using a laser
microscope and 6.6, 8.1, and 11.9 µm at 1.7,
3.0, and 4.3 J/mm2.

deposited films fabricated using the PTFE target
with various X-ray doses. Peaks were observed at2θ = 16 and 18° at X-ray doses of 3.0 and
4.3 J/mm2, similar to those observed for pristine
PTFE. This result indicates that the crystalline
structure of the deposited film is similar to that of
PTFE at these X-ray doses.

Crystalline peak(a)Intensity (a. u.)

3
2

(a)

Amorphous
peak

Intensity (a.u.)

1
0

10

15

20

25

Angle 2θ (deg.)

Transmittance

1

2
4
6
8
Photon energy (keV)

10

(b)

(b)
20 µm
50 µm
100 µm300 µm

0.8
0.6

(A)

Intensity (a. u.)

0

(B)
(C)

0.4
0.2
0

10
0

2
4
6
8
Photon energy (keV)

10

15
20
Angle 2θ (deg.)25

Fig. 2. XRD spectrum of (a) 0.1 mm thick PTFE
and (b) the deposited film fabricated using thePTFE target with X-ray irradiation doses of (A) 4.3,
(B) 3.0, (C) 1.7 J/mm2.

Fig. 1. (a) Calculated SR spectrum at 1.5 GeV
recorded at the exposure stage on beamline BL-11.
(b) Photon energy dependence of X-ray
transmittance through PTFE substrates withvarious thicknesses of 20, 50, 100, and 300 µm.

Conclusion
In this study, a novel deposition process wasdeveloped to fabricate a thin PTFE film using
high-energy X-rays from 2–8 keV. A PTFE
substrate was irradiated using X-rays and thedeposition was carried out under atmospherepressure by heating the PTFE target anddepositing the fragments desorbed from thesurface onto a glass substrate. Using this method,a thin film with a thickness of above 10 µm wasachieved. The crystalline structures of thedeposited films were evaluated using XRD. The
XRD data of the samples were compared withthose of the pristine PTFE substrate and it was

The crystalline structures of the deposited films
on glass substrates were measured by XRD usinga Rigaku-D/tex Ultra 250 equipped with a CuKα
radiation source ( = 1.5406 Å). The XRD
spectrum of a 0.1 mm thick pristine PTFE
substrate without SR irradiation is shown in
Fig. 2 (a). Diffraction peaks derived from
amorphous and crystalline material wereobserved at 2θ = 16 and 18°, respectively, whichcorrespond with previously reported values[9,12]. Figure 2 (b) shows the XRD spectra of the64found that the crystalline structures of the sample
films are similar to those of the pristine PTFE
substrate. The technique used in this study tofabricate PTFE thin films can be easily used toperform surface modification and can be applied
to various applications.
References[1] F. Liu, B. Yi, D. Xing, J. Yu, and H. Zhang, J.
Memb. Sci., 212, pp.213-223 (2003).
[2] H. Zhu, H. Wang, F. Wang, Y. Guo, H. Zhang,and J. Chen, J. Memb. Sci., 446, pp.145-153(2013).
[3] T. C. Nason, J. A. Moore, and T.–M. Lu, Appl.
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Photopolym. Sci. Technol., 29, pp.403-407(2016).
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J. Synchrotron. Rad., 26, pp.528-534 (2019).

65

Modification of optical property of a Polytetrafluoroethylene
by Synchrotron Radiation
Masaya Takeuchi, Akinobu Yamaguchi, Yuichi Utsumi
Laboratory and Advanced Science and Technology for Industry, University of Hyogo

Abstract

We demonstrate the modification of transmittance of bulk polytetrafluoroethylene (PTFE) via
synchrotron X-ray irradiation. X-ray irradiation of the PTFE substrate is conducted to mechanicallysuppress the photoevaporation of PTFE molecules. This method drastically increases the ultraviolet
and visible transmittance of the irradiated areas of the substrates, with greater than 80%
transmittance observed at the 350-nm wavelength. We observed the irradiated area via scanningelectron microscopy and determined that this optical property modification is due to thehomogenization of the bulk PTFE texture with nanometer to micron-sized pores. We expect that thismodified PTFE will be employed as a construction material for various micro system devices such
as Lab-on-a-chip and micro total analysis systems.

Introduction
Polytetrafluoroethylene (PTFE) has excellent
material properties, such as high heat andchemical resistance, high mechanical strength,
electrical insulation, a low dielectric constant,and low coefficient of friction. These ideal
characteristics make PTFE an attractive material
for microsystems such as micro-electro
mechanical systems (MEMS), micro total
analysis systems (µTAS), and Lab-on-a-chip(LOC). However, PTFE microfabrication and its
bulk modification are difficult owing to theoutstanding thermal and chemical stability ofPTFE, with most PTFE research conducted using
either x /γ , α, electron beam (EB), or neutronradiation to date [1–17].
The direct etching of PTFE induced bysynchrotron radiation (SR) irradiation [1-3] andthe precise process characteristics of PTFE
etching using a high-energy (2–12 keV) X-ray
and heat assistance have been studied extensively[4–7]. For example, tentative bubble-likestructures were observed on the X-ray irradiatedsurface of PTFE substrates via scanning electron
microscopy (SEM), and the results indicated that
surface liquefaction occurred during thephotolysis of bulk PTFE, with the desorption ofphotoproducts from the surface and subsequentdegradation of the PTFE molecules [4–6].
Raman spectroscopy and X-ray diffraction
measurements of the X-ray irradiated PTFE
surfaces suggested that the chain scissions of
PTFE were driven to completion [7], withconfirmation that the melting temperature of theirradiated PTFE decreased because the molecularweight decreased owing to the chain scission of
PTFE via X-ray irradiation, resulting in theevaporation of photoproducts from the surface.

Furthermore, it has been reported that themodification of the optical properties of PTFE
results in the transformation of the original
opaque PTFE substrates into transparent PTFE
substrates after several MeV of EB irradiation
while in the molten state [9].
Here we report on the optical modification of
bulk PTFE by suppressing the evaporation of thephotoproducts generated via X-ray irradiation on
the PTFE substrate, which drastically increases
its ultraviolet (UV) and visible transmittance.
Experiments and Results
The SR irradiation experiment on the PTFE
substrates was conducted at beam line BL-11[18] of the NewSUBARU SR facility at the
University of Hyogo, Japan. The storage ring
electron kinetic energy was set at 1.5 GeV, with astorage ring current of 160–320 mA. Each PTFE
substrate (500-µm thickness) was enclosed in a
12-µm-thick Al film barrier layer. The sample
heating was adjusted to maintain an incident SR
beam that was perpendicular to the PTFE surface
in the reaction chamber, and the PTFE surface
was vertically scanned to ensure a homogeneous
intensity distribution, which was performed bymoving the exposure stage. The SR irradiationdose was controlled by changing the number ofscans. The X-ray irradiation was conducted withheating in a vacuum. The dashed line of Fig. 1
shows the calculated spectrum in BL-11. The line
is obtained by the 1.5 GeV operation with astorage ring current of 300 mA. The solid line ofFig. 1 shows the spectrum of the beam adding thetransmission of the Al film barrier layer of PTFE
substrate to the above spectrum. The photon
energy of the X-ray irradiated PTFE substrates

66

spans the 3–8 keV range. Additionally, the UV
and visible transmittance of the irradiated area ofthe substrates were measured using aspectrophotometer.
We performed X-ray irradiation of the PTFE
substrates under 4 ± 2 Pa pressure and a heating
temperature of 200 °C. The SR doses were 0, 13,
23, 26, and 33 J/cm2 with the 1.5 GeV operation
in BL-11. The transmittance increases withhigher SR doses, as shown in Fig. 2, with morethan 80% transmittance at the 350-nm
wavelength and SR dose of 33 J/mm2.

transmittance owing to light scattering because
they are produced via sintering as-polymerized
powder, and their bulk morphology comprises a
porous texture with nanometer to micron-sizedpores [19]. However, it is confirmed that thePTFE melting point decreases via SR irradiation
and allows the material from the irradiated area
to infiltrate the pores in the non-irradiated area as
the melting liquid; this leads the homogenizationof the bulk PTFE texture. Figure 3 shows a SEM
image of an SR-irradiated PTFE surface thatsuppressed the evaporation of photochemical
products in BL-11, with an SR dose of 33 J/mm2.
As mentioned above, we confirmed that this
optical property modification arose with thehomogenization of bulk PTFE. Further, we
assume that the degradation in the crystallinity of
the PTFE bulk texture owing to SR irradiation isanother contributing factor.

After passing
12-µm-thick Al film

Intensity (a. u.)

BL11tConclusion
In this paper, we demonstrate that X-ray
irradiation modifies bulk PTFE by mechanicallySR-irradiated surface
0

2

4
6
8 10
Photon energy (keV)

Original PTFE surface

12

Fig. 1. Calculated photon intensity spectrum of
the X-ray obtained from BL-11 at
NewSUBARU (1.5 GeV operation; dashed line)
and that after passing 12-µm-thick Al film (solidline).
100

(f)

80

(e)

(d)

Fig. 3. SEM images of a PTFE surface irradiatedin beam line BL-11 at NewSUBARU.

(c)Fig. 2. Transmittance of the X-ray irradiated
PTFE in the visible light region: (a) 0, (b) 13,(c) 23, (d) 25, (e) 26, (f) 33 J/mm2.

suppressing photoevaporation of the PTFE
molecules and drastically increases the UV andvisible transmittance of the PTFE molecules. We
suggest that the modification of the transmittanceof bulk PTFE is caused by the homogenization of
bulk PTFE. It is expected that this modified
PTFE will be employed as a construction
material in various micro system devices, such as
LOC and µTAS, for the observation of cells andchemiluminescent immunoassays to detect target
substances in microliquids.

Our results demonstrate that the drasticchange in the transmittance of bulk PTFE via SR
irradiation is attributed to the homogenization of
the bulk PTFE substrate. Commercialized PTFE
substrates generally possess a low UV and visible

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(b)

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68

Part 3. List of Publications

Retirement memorial lecture of Prof. Shuji Miyamoto69

(1) Papers

List of publications

1.

"Performance measurement of HARPO: A time projection chamber as a gamma-ray telescope andpolarimeter"
P. Gros, S. Amano, D. Attié, P. Baron, D. Baudin, D. Bernard, P. Bruel, D. Calvet, P. Colas, S. Daté, A. Delbart,
M. Frotin, Y. Geerebaert, B. Giebels, D. Götz, S. Hashimoto, D. Horan, T. Kotaka, M. Louzir, F. Magniette, Y.
Minamiyama, S. Miyamoto, H. Ohkuma, P. Poilleux, I. Semeniouk, P. Sizun, A. Takemoto, M. Yamaguchi, R.
Yonamine, S. Wang
Astroparticle Physics, 97, pp.10-18 (2018).

2.

"Development of positron annihilation measurement system with fast positron created by laser Compton
scattering γ-ray at NewSUBARU synchrotron facility"
Fuminobu Hori, Kento Sugita, Akihiro Iwase, Mititaka Terasawa, Shuji Miyamoto
日本陽電子科学会「陽電子科学」第 10 号, ISSN 2188-0107 pp.21-28(2018).

3.

"Photon-flux determination by the Poisson-fitting technique with quenching corrections"
H.Utsunomiya, T. Watanabe, T. Ari-izumi Daiki Takenaka, T. Araki, K. Tsuji, I. Gheorghe, D. M. Filipescu, S.
Belyshev, K. Stopani, D. Symochko, H. Wang, G. Fan, T. Renstrøm, G. M. Tveten, Y.-W. Lui, K. Sugita,
S.Miyamoto
Nuclear Instruments and Methods in Physics Research A, 896, pp.103-107 (2018).

4.

"Measurements of Neutrons from Photonuclear Reactions using Laser Compton Scattering Gamma rays"
S. Miyamoto, A. Takemoto, M. Yamaguchi, K. Sugita, S. Hashimoto, S. Amano
Plasma and Fusion Research, 13, 2404066 (2018).

5.

"A Comprehensive Analysis of Polarized γ-ray Beam Data with the HARPO Demonstrator"
R.Yonamine, S. Amano, D. Atti ́e, P. Baron, D. Baudin, D. Bernard, P. Bruel, D. Calvet, P. Colas, S. Dat ́e, A.
Delbart, M. Frotin, Y. Geerebaert, B. Giebels, D. G otz, P. Gros, S. Hashimoto, D. Horan, T. Kotaka, M. Louzir, F.
Magniette, Y. Minamiyama, S. Miyamoto, H. Ohkuma, P. Poilleux, I. Semeniouk, P. Sizun, A. Takemoto, M.
Yamaguchi, and S. Wang
Proceedings of International Conference on Technology and Instrumentation in Particle Physics 2017, pp. 27-30(2018).

6.

"Photoneutron cross sections for Ni isotopes: Toward understanding (n, gamma ) cross sections relevant to
the weak s-process nucleosynthesis"
H. Utsunomiya, T. Renstrøm, G. M Tveten, S. Goriely, S. Katayama, T. Ari-izumi, D. Takenaka, D. Symochko,
B. V. Kheswa, V.W. Ingeberg, T. Glodariu†, Y.-W. Lui, S. Miyamoto, A. C. Larsen, J. E. Midtbø, A. G orgen, S.
Siem, L. Crespo Campo, M. Guttormsen, S. Hilaire, S. P ́eru, and A. J. Koning
Physical Review C, 98, 054619 (2018).

7.

"The γ-ray Strength Function for Thallium Isotopes relevant to the 205Pb-205Tl Chronometry"
H. Utsunomiya, T. Renstrøm, G. M Tveten, S. Goriely, T. Ari-izumi, D. Filipescu, I. Gheorghe, Y.-W. Lui, W. Luo,S. Miyamoto, A. C. Larsen, S. Hilaire, S. P ́eru, and A. J. Koning
Phys. Rev. C 99, 024609 (2019).

8.

"レーザーコンプトン散乱ガンマ線による高速陽電子を用いた材料欠陥検査システムの開発"
杉田健人, 森本悠介, 橋本智, 天野壮, 堀 史説, 岩瀬彰宏, 寺澤倫孝, 宮本修治
日本物理学会第 73 回年次大会予稿集, 25aK606-4 (2018).

9.

"γ線 Tracking 検出器の開発と性能評価"
甲田 旭, 青井 考, 山本康嵩, 井手口栄治, MUKHI KUMAR RAJU, Hoang Thi Ha, Tung Thanh Pham, 嶋達志, 柳原陸斗, Viljamaa Topi Benjamin, 宮本修治, 静間俊行
日本物理学会第 73 回年次大会予稿集, 25aK302-10 (2018).

10. "NewSUBARU BL01 ビームラインの整備と実験"
宮本 修治
1
70

原子力学会春の年会( 2018)予稿集, 放射線工学部会セッション, 2H_PL03「レーザー逆コンプトン放射線場による放射線工学の新たな展開」
11. "帯域可変ガンマ線分光器のための櫛歯結晶の設計と試作"
羽島良一, 早川岳人, 静間俊行, 沢村勝, 永井良治, 宮本修治, 松葉俊哉
原子力学会春の年会(2018)予稿集,2018.3.26-28 大阪大学吹田キャンパス.
12. "巨大共鳴領域で金から発生する光中性子の非等方性パラメータ"
波戸 芳仁, 桐原 陽一, 佐波 俊哉, 糸賀 俊朗, 中島 宏, 宮本 修治, 浅野 芳裕
原子力学会春の年会(2018)予稿集, 2018.3.26-28 大阪大学吹田キャンパス.
13. "光中性子エネルギースペクトルに対する入射光子エネルギー依存性の測定"
佐波俊哉, 桐原陽一, 波戸芳仁, 糸賀俊朗, 中島宏, 宮本修治, 浅野芳裕
原子力学会春の年会(2018)予稿集, 2018.3.26-28 大阪大学吹田キャンパス.
14. "Development of a variable-bandwidth monochromator for next-generation gamma sources"
Ryoichi Hajima, Takehito Hayakawa, Toshiyuki Shizuma, Masaru Sawamura, Ryoji Nagai, Shuji Miyamoto,
Shunya Matsuba
Proceedings of the 15th Annual Meetings of Particle Society of Japan, THP021 (2018).
15. "Study of laser Compton gamma-ray source using laser diode array"
Sho Amano, Taku Yoshikawa, Shuji Miyamoto
Proceedings of the 15th Annual Meetings of Particle Society of Japan, THP107 (2018).
16. "Material Inspection by positron generated by LCS gamma-ray"
Shuji Miyamotoi, Kento Sugita, Fuminobu Hori, Mititaka Terasawa, Akihiro Iwase, Sho Amano, Satoshi
Hashimoto
Proceedings of the 15th Annual Meetings of Particle Society of Japan, THP108 (2018).
17. "Present status of the NewSUBARU synchrotron light facility"
Shuji Miyamoto, Yoshihiko Shoji, Satoshi Hashimoto, Yasuyuki Minagawa, Kazuyuki Kajimoto, Yousuke
HamadaProceedings of the 15th Annual Meetings of Particle Society of Japan, FSP025 (2018).
18. "How Students Understand the Visual Grade Report"
Yoshihiko Shoji and Yoshihiro Kokubo
Proc. of 7th International Conference on Learning Technologies and Learning Environments (LTLE2018), IEEE
Explore.
19. "Erosion of fluorinated diamond-like carbon films by exposure to soft X-rays"
Kazuhiro Kanda, Hiroki Takamatsu, Eri Miura-Fujiwara, Hiroki Akasaka, Akihiro Saiga, and Koji Tamada
Japanese Journal of Applied Physics 57, 045501 (2018)20. "Low-temperature activation of boron ion in silicon substrate using B10H14+ cluster and by soft X-ray
irradiation"
Akira Heya, Naoto Matsuo, and Kazuhiro Kanda
Japanese Journal of Applied Physics 57 (2018) 116502,
https://doi.org/10.7567/JJAP.57.116502.
21. "Semimetallicity of free-standing hydrogenated monolayer boron from MgB2"
I. Tateishi, N. T. Cuong, C. A. S. Moura, M. Cameau, R. Ishibiki, A. Fujino, S. Okada, A. Yamamoto, M. Araki,
S. Ito, S. Yamamoto, M. Niibe, T. Tokushima, D. E. Weibel, T. Kondo, M. Ogata, and I. Matsuda
Phys. Rev. Mater., 3, 024004 (2019) DOI: 10.1103/PhysRevMaterials.3.024004.
271

22. "Removal of carbon contamination on oxidation-prone metal-coated mirrors using atomic hydrogen"
Masahito Niibe, Tetsuo Harada, Akira Heya, Takeo Watanabe, Naoto Matsuo
AIP Conf. Proc. 2054, 060010 (2019). DOI: 10.1063/1.5084641
23. "Effects of ultraviolet wavelength and intensity on AlGaN thin film surfaces irradiated simultaneously with
CF4 plasma and ultraviolet"
Retsuo Kawakamia, Masahito Niibe, Yoshitaka Nakano, Shin-ichiro Yanagiya, Yuki Yoshitani, Chisato Azuma,
Takashi Mukai
Vacuum, 159, 45-50 (2018). doi.org/10.1016/j.vacuum.2018.10.017
24. "Electron Structure of Boron Doped HOPG: Selective Observation of Carbon and Trace Dope Boron by
Means of X-ray Emission and Absorption Spectroscopy"
Masahito Niibe, Noritaka Takehira, Takashi Tokushima
e-J. Surf. Sci. Nanotech, 16, 122-126 (2018). doi: 10.1380/ejssnt.2018.122
25. "Laser plasma soft X-ray source in the water window based on cryogenic targets"
S.AmanoElectronics and Communications in Japan, Vol.101, Issue 1, 55- 60(2018)26. "Laser plasma vacuum ultraviolet light source using solid rare-gas targets"
S.AmanoJpn. J. Appl. Phys., Vol. 57, 086201(2018)27. "Water-window soft X-ray source using cryogenic Ar laser plasma"
S.AmanoJpn. J. Appl. Phys., Vol. 57, 126201(2018)28. "Plasmon confinement by carrier density modulation in graphene"
Ngoc Han Tu, Makoto Takamura, Yui Ogawa, Satoru Suzuki, and Norio Kumada
Japanese Journal of Applied Physics 57, 110307 (2018).
29. "Surface structures of graphene covered Cu(103)"
Yui Ogawa, Yuya Murata, Satoru Suzuki, Hiroki Hibino, Stefan Heun, Yoshitaka Taniyasu, and Kazuhide
Kumakura
Japanese Journal of Applied Physics 57, 100301 (2018).
30. "Quasi-free-standing monolayer hexagonal boron nitride on Ni "Satoru Suzuki, Yuichi Haruyama, Masahito Niibe, Takashi Tokushima, Akinobu Yamaguchi, Yuichi Utsumi,
Atsushi Ito, Ryo Kadowaki, Akane Maruta and Tadashi Abukawa
Materials Research Express, Volume 6, Number 1, 016304, 201931. "H2O/O2 Vapor Annealing Effect on Spin Coating Alumina Thin Films for Passivation of Silicon Solar
Cells"
Abdullah Uzum, Hiroyuki Kanda, Takuma Noguchi, Yuya Nakazawa, Shota Taniwaki, Yasushi Hotta, Yuichi
Haruyama, Naoyuki Shibayama, and Seigo Ito
International Journal of Photoenergy, Volume 2019, Article ID 4604932, 7 pages
https://doi.org/10.1155/2019/4604932
32. "Water Electrolysis using Flame-Annealed Pencil Graphite Rods"
Ryuki Tsuji, Hideaki Masutani, Yuichi Haruyama, Masahiro Niibe, Satoru Suzuki, Shin-ichi Honda, Yoshiaki
Matsuo, Akira Heya, Naoto Matsuo and Seigo Ito
ACS sustainable chemistry engineering, 7, 5681-5689, 201933. "The Current Status and Technical Issues and Future Prospect for Extreme Ultraviolet Lithography"
372Takeo Watanabe
HORIBA Technical Journal, Readout, 1, 50-55, 2018.
34. "Reflectance measurement of EUV mirrors with s- and p-polarization light using polarization control unit"
Tetsuo Harada, Takeo Watanabe
Proc. SPIE 10809 (2018) 108091T.
35. "Development of Absorption-Coefficient-Measurement Method of EUV Resist by Direct-Resist Coating on
a Photodiode"
Shota Niihara, Tetsuo Harada, Takeo Watanabe
Proc. SPIE 10809 (2018) 108091Y.
36. "Fabrication of High-Aspect-Ratio Transmission Grating Using DDR Process for 10-nm EUV Resist
Evaluation by EUV Interference Lithography"
Mana Yoshifuji, Shota Niihara, Tetsuo Harada, and Takeo Watanabe
J. Photopolym. Sci. Technol. 31 (2018) pp. 215-220.
37. "Synthesis and Property of Tannic Acid Derivatives and Their Application for Extreme Ultraviolet
Lithography System"
Hiroto Kudo, Shizuya Ohori, Hiroya Takeda, Hiroki Ogawa, Takeo Watanabe, Hiroki Yamamoto, Takahiro
KozawaJ. Photopolym. Sci. Technol., 31, 221-225 (2018).
38. "In-Situ Measurement of Outgassing Generated from EUV Metal Oxide Nanoparticles Resist During
Electron Irradiation"
Seiji Takahashi, Hiroko Minami, Yoko Matsumoto, Yoichi Minami, Mikio Kadoi, Atsushi Sekiguchi, Takeo
WatanabeJ. Photopolym. Sci. Technol., 31, 257-260 (2018).
39. “Synthesis of Hyperbranched Polyacetals Containing C-(4-t-butylbenz)calix[4]resorcinarene: Resist
Properties for Extreme Ultraviolet (EUV) Lithography”
Hiroto Kudo, Mari Fukunaga, Kohei Shiotsuki, Hiroya Takeda, Hiroki Yamamoto, Takahiro Kozawa, Takeo
Watanabe
Reactive and Functional Polymers, 131, 361–367 (2018).
40. "Ferromagnetic resonance of Ni wires fabricated on ferroelectric LiNbO3 substrate for studying magnetic
anisotropy induced by the heterojunction"
Akinobu Yamaguchi, Akiko Nakao, Takuo Ohkochi, Akira Yasui, Toyohiko Kinoshita, Yuichi Utsumi,
Tsunemasa Saiki and Keisuke Yamada
AIP Advances 8, 056411 (2018).
41. "Heterojunction-induced magnetic anisotropy and magnetization reversal of Ni wires on LiNbO3
substrate"
Akinobu Yamaguchi, Takuo Ohkochi, Akira Yasui, Toyohiko Kinoshita, and Keisuke Yamada
Journal of Magnetism and Magnetic Materials, 453, 107-113 (2018).
42. "環境分析や食品安全のための高次ナノ構造体を用いた微量分子検出システムの検討"
山口明啓，福岡隆夫，内海裕一
電気学会誌 E 部門誌 Vol. 138, No. 5, pp. 191 197 (2018).
IEEJ Transaction on Sensors and Micromachines Vol. 138, No. 5, pp. 191 197 (2018).
43. "Study on fabrication of moleculer sensing system using higher-order nanostructure for environmental
analysis and food safety"
Akinobu Yamaguchi, Takao Fukuoka, Yuichi Utsumi
473

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47.

"Nano-polycrystalline diamond synthesized from neutron-irradiated highly oriented pyrolytic
graphite (HOPG),"
Mititaka Terasawa, Shin-ichi Honda, Keisuke Niwase, Masahito Niibe, Tomohiko
Hisakuni, Tadao Iwata, Yuji Higo, Toru Shinmei, Hiroaki Ohfuji, Tetsuo
Irifune, Diamond & Related Materials, 82, 132-136 (2018).

48. "Quenchable compressed graphite synthesized from neutron-irradiated highly oriented pyrolytic
graphite in high pressure treatment at 1500 ℃"
Keisuke Niwase, Mititaka Terasawa, Shin-ichi Honda, masahiti Niibe, Tomohiko
Hisakuni, Tadao Iwata, Yuji Higo, Takeshi Hirai, Toru Shinmei, Hiroaki
Ohfuji, Tetsuo Irifune, Journal of Applied Physics, 123, 16 (2018).

5

74

(2) International meetings
1.

"Photoneutron measurements for IAEA CRP on updating the current photonuclear data library"(Oral)
I. Gheorghe, H. Utsunomiya, T. Ari-izumi, D. Takenaka, S. Belyshev, K. Stopani, V. Varlamov, D.
Filipescu, M. Krzysiek, G. Tveten, T. Renstrøm, D. Symochko, H. Wang, G. Fan, S. Miyamoto
Nuclear Photonics 2018, 24-29 June 2018, Brasov, Romania.

2.

"Research Project on Laser-Driven Neutron sources and applications at ILE, Osaka University"(Poster)
M. Nakai, Y. Arikawa, A. Yogo, Y. Abe, Y. Kato, S. Matsubara, S. Tosaki, K. Koga, N. Iwata, H.
Nagatomo, A. Moracel, K. Mima, Y. Otake, S. Miyamoto, H. Nihsimura, S. Sakabe and S. Inoue
Nuclear Photonics 2018, 24-29 June 2018, Brasov. Romania.

3.

"Non-distractive Inspection of Material Defect by Positron Generated by Laser Compton
Scattering Gamma-ray Beam" (Oral)
S. Miyamoto, K. Sugita, M. Terasawa, F. Hori, A. Iwase, S. Amano and S. Hashimoto
Nuclear Photonics 2018, 24-29 June 2018, Brasov, Romania.

4.

"Development of a positron annihilation measurement system by implantation of 17 MeV gamma
beam into bulk materials" (Oral)
K. Sugita1, S. Miyamoto, M. Terasawa, A. Iwase, K. Umezawa, F. Hori
International Conference on Positron Annihilation, ICPA18, Orlando, August 19-24 (2018).

5.

"Photoneutron Cross Section Measurements for 165Ho by Direct Neutron-Multiplicity Sorting at
NewSUBARU" (Oral)
M. Krzysiek, H. Utsunomiya, I. Gheorghe, D. M. Filipescu, T. Renstrøm, G. M. Tveten, S. Belyshev, K.
Stopani, H. Wang, G. Fan, Y-W. Lui, D. Symochko, S. Goriely, A-C. Larsen, S. Siem, V. Varlamov, B.
Ishkhanov, T. Ari-izumi, S. Miyamoto
Zakopane Conference on Nuclear Physics, 26th August to 2nd September 2018, Zakopane, Poland.

6.

"γ-ray Strength Functions and Partial GDR Cross Sections in the IAEA Photonuclear Data
Project"
H. Utsunomiya, I. Gheorghe, D.M. Filipescu, K. Stopani, S. Belyshev, T. Renstrøm, G.M. Tveten, S.
Goriely, Y.-W. Lui, T. Ari-izumi, S. Miyamoto, V. Varlamov, B. Ishkhanov, A.C. Larsen, S. Siem
6th International Workshop on Compound-Nuclear Reactions and Related Topics, CNR18, Berkeley,
September 24-28 (2018).

7.

"NewSUBARU BL05 - A industrial analysis beam line in soft and tender X-ray region" [2P059]
Takayuki Hasegawa, Masaharu Uemura, Tohru Awane, Noboru Fukada, Kazuhiro Kanda, Sei Fukushima
ICG Annual Meeting, 2018.9.23-26, Pacifico Yokohama

8.

"Local structure analysis of Si-containing DLC films by X-ray absorption spectroscopy" [key note]
Kazuhiro Kanda
The 3rd SLRI-NUT-SIAT Colloquium 2018, 2018.11.21, Synchrotron Light Research Institute,
NakhonRatchasima, Thailand

9.

"1H NMR Detection on Nitrogen Terminated Diamond by Shallow Nitrogen Vacancy Centers"[EP09.03.03]
Takahiro Sonoda, Sora Kawai, Hayate Yamano, Jorge J. Buendia, Taisuke Kageura, Yu Ishii, Kiro
Nagaoka, Ryosuke Fukuda, Takashi Tanii, Moriyoshi Haruyama, Keisuke Yamada, Shinobu Onoda,
Wataru Kada, Osamu Hanaizumi, Alastair Stacey, Kazuhiro Kanda, Masaharu Uemura, Tokuyuki Teraji,
Junichi Isoya, Shozo Kono and Hiroshi Kawarada

1

75

MRS Fall Meeting & Exhibit, 2018.11.25-30, the Hynes Convention Center Boston, Massachusetts, USA
10. "Development of On-site Cleaning Method of Carbon Contamination with Atomic Hydrogen"
Masahito Niibe, Takashi Tokushima, Tomohiko Kono, Yusuke Hashimoto, Yuka Horikawa, and Hiroaki
YoshidaThe 23rd Hiroshima International Symposium on Synchrotron Radiation, Higashi-Hiroshima, 7-8, March
2019.
11. "Effect of Atmospheric-Pressure O2 Plasma-Assisted Annealing on Photocatalytic Activity of TiO2
Nanoparticles"
Yuki Yoshitani, Retsuo Kawakami, Hirofumi Koide, Naoki Takami, Masahito Niibe, Yoshitaka Nakano,
Chisato Azuma and Takashi Mukai
Proceedings of International Symposium of Dry Process 2018, 255-256, Nagoya, Nov. 2018.
12. "Hydrophilic Modification of Polypropylene Film Surfaces Treated by Atmospheric-Pressure Air
Plasma Jet"
Retsuo Kawakami, Yuki Yoshitani, Kimiaki Mitani, Naoki Takami, Hirofumi Koide, Norihiro Sugimoto,
Masahito Niibe, Yoshitaka Nakano, Chisato Azuma and Takashi Mukai
Proceedings of International Symposium of Dry Process 2018, 253-254, Nagoya, Nov. 2018.
13. "Water Electrolyzing Catalyst of Pt and Fe, Ni, Ru-O Catalysts Deposited by Flame-Annealing on
Carbon Electrode"
R. Tsuji, H. Masutani, M. Niibe, Y. Haruyama, A. Heya, S. Nakajima, N. Matsuo, H. Fujisawa, S. Honda,
S. Ito2018 Annual Nanotechnology Conf., Viena, Austria, Sep. 3-5 2018.
14. "Water Electrolysis using Flame-Annealed Pencil Carbon Electrode"
H. Masutani, R. Tsuji, M. Niibe, A. Heya, N. Matsuo, Y. Matsuo, S. Honda, S. Ito2018 Annual Nanotechnology Conf., Viena, Austria, Sep. 3-5 2018.
15. "Removal of carbon contamination on easily-oxidizable-metal coated mirrors for synchrotron
radiation beamlone using atomic hydrogen"
Masahito Niibe, Tetsuo Harada, Akira Heya, Takeo Watanabe, Naoto Matsuo
Inter’l. Conf. Hot Wire & Initiated Chemical Vapor Deposition (HWCVD10), Kitakyushu, Japan, 3-6, Sep.
2018.
16. "Removal of carbon contamination on oxidation-prone metal-coated mirrors using atomic
hydrogen"Masahito Niibe, Tetsuo Harada, Akira Heya, Takeo Watanabe, Naoto Matsuo
Inter’l. Conf. Synchrotron Rad. Instrumentation (SRI 2018), Taipei Taiwan, 10-15, June 2018.
17. "Cryogenic-Ar laser-plasma-source"
S.Amano (Invited)
World Congress on Plasma Science and Technology (WCPST2018), Stockholm, Sweden, November 4-7,
2018.
18. "Growth Process of Hexagonal Boron Nitride in the Diffusion and Precipitation Method Studied by
X-ray Photoelectron Spectroscopy"
Satoru Suzuki, Yuichi Haruyama
14th Int. Conf. Atomically Controlled Surfaces and Interfaces (ACSIN14), Sendai, October 22, 2018.

27619. "Quasi-Free-Standing Monolayer Hexagonal Boron Nitride on Ni Studied by XAS, XES, and
PEEM"
Satoru Suzuki, Yuichi Haruyama, Masahito Niibe, Takashi Tokushima, Akinobu Yamaguchi, Yuichi
Utsumi, Atsushi Ito, Ryo Kadowaki, Akane Maruta, and Tadashi Abukawa
International Workshop on Trends in Advanced Spectroscopy in Materials Science (TASPEC), Hiroshima,
October 6, 2018.
20. "Evaluation on the molecular orientation in photoreactive liquid crystalline polymer films by
NEXAFS spectroscopy"
Y. Haruyama, M. Okada, M. Kondo, and N. Kawatsuki
14th International Conference on Electron Spectroscopy and Structure (ICESS-14), ShanhaiTech
University, Shanhai, China, October 8, 201821. "EUV Application Research at NewSUBARU"
T. Watanabe and T. Harada
Optics and Photonics International Congress, Yokohama, 2018/4/23-27. (Invited)
22. "Synthesis and Property of Tannic Acid Derivatives and Their Application for Extreme Ultraviolet
Lithography System"
Hiroto Kudo, Shizuya Ohori, Hiroya Takeda, Hiroki Ogawa, Takeo Watanabe, Hiroki Yamamoto,
Takahiro Kozawa
The 35th International Conference of Photopolymer Science and Technology, Makuhari Messe, Chiba,
Japan, 2018/6/25-28. (Invited)
23. "In-Situ Measurement of Outgassing Generated from EUV Metal Oxide Nanoparticles Resist
During Electron Irradiation"
Seiji Takahashi, Hiroko Minami, Yoko Matsumoto, Yoichi Minami, Mikio Kadoi, Atsushi Sekiguchi,
Takeo Watanabe
The 35th International Conference of Photopolymer Science and Technology, Makuhari Messe, Chiba,
Japan, 2018/6/25-28.
24. "Fabrication of High-Aspect-Ratio Transmission Grating Using DDR Process for 10-nm EUV
Resist Evaluation by EUV Interference Lithography"
Mana Yoshifuji, Shota Niihara, Tetsuo Harada, and Takeo Watanabe
ICPST35, Chiba, Japan, 2018/6/25-28.
25. "Photopolymer Technology for Extreme Ultraviolet Lithography"
Takeo Watanabe, Tetsuo Harada
Polymer World Congress, Stockholm, Sweden, 2018/9/3-6. (Invited)
26. "Reflectance measurement of EUV mirrors with s- and p-polarization light using polarization
control unit"
Tetsuo Harada, Takeo Watanabe
EUV Lithography Symposium 2018, Monterey, USA, 2018/9/18.
27. "Development of Absorption-Coefficient-Measurement Method of EUV Resist by Direct-Resist
Coating on a Photodiode"
Shota Niihara, Tetsuo Harada, Takeo Watanabe
EUV Lithography Symposium 2018, Monterey, USA, 2018/9/18.
28. "Research Activities of Extreme Ultraviolet Lithography at University of Hyogo"

377

Takeo Watanabe, Tetsuo Harada
Micro Nano Engineering 2018, Copenhagen, 2018/9/24-27.
29. "Research activity of evaluation tools including soft X-ray optics for the research of EUV
lithography at University of Hyogo"
Takeo Watanabe, Tetsuo Harada
Physics of X-Ray and Neutron Multilayer Structures (PXRNMS) 2018, Paris, 2018/11/7-9.
30. "Development of EUV Phase Imaging Microscope for Mask-3D-Effect and Defect Evaluation"
Tetsuo Harada, Takeo Watanabe
MNC2018, Sapporo, Japan, 2018/11/14. (Invited)
31. "Fabrication of High-Aspect-Ratio Transmission Grating Using DDR Process for 10-nm EUV
Resist Evaluation by EUV Interference Lithography"
Mana Yoshifuji, Tetsuo Harada, Takeo Watanabe
MNC2018, Sapporo, Japan, 2018/11/14.
32. "Magnetic field dependence of ferromagnetic resonance of Ni wires fabricated on ferroelectric
LiNbO3 substrate for studying magnetic anisotropy induced by the heterojunction"
A. Yamaguchi, A. Nakao, Y. Utsumi, T. Saiki, Y. Takizawa, T. Ogasawara, K. Yamada
INTERMAG 2018 Conference, Singapore, April 23-27, 201833. "Heterojunction-induced Magnetic Anisotropy of Ni Wires on LiNbO3 Substrate"
Akinobu Yamaguchi
5th International Conference of Asian Union of Magnetics Societies (IcAUMS 2018), Jeju, Korea, June
3-7, 2018, (INVITED)
34. "Dielectrophoresis-controllable aggregation and dispersion of Aunanoparticles-decorated
polystyrene beads with SERS-activity"
Akinobu Yamaguchi, Yuichi Utsumi, Takao Fukuoka
International Conference on Advancing Molecular Spectroscopy, Nishinomiya Campus of Kwansei
Gakuin University, Hyogo, Japan, June 30 - July 1, 201835. "The Self-assembly of Gold Nanoparticles is Available to SERS Nanobeacons"
Takao Fukuoka, Yasushige Mori, Akinobu YamaguchiInternational Conference on Advancing Molecular Spectroscopy, Nishinomiya Campus of Kwansei
Gakuin University, Hyogo, Japan, June 30 - July 1, 201836. "The study on magnetization reversal of zebra-stripe domain structure in Ni wires fabricated on a
LiNbO3 substrate"
A. Yamaguchi, K. Yamada, A. Nakao, T. Saiki, Y. Utsumi and T. Ogasawara
21st International Conference on Magnetism (ICM2018), San Francisco, USA, July 15-20, 201837. "Wire width dependence of ferromagnetic resonance in Ni wires on ferroelectric LiNbO3 substrate
for studying heterojenction-induced magnetic characteristics"
A. Yamaguchi, A. Nakao, T. Saiki, Y. Utsumi, T. Ogasawara and K. Yamada
21st International Conference on Magnetism (ICM2018), San Francisco, USA, July 15-20, 201838. "The Study on the Generation of Magnetic Anisotropy Induced by the Heterojunction between
Ferromagnetic and Ferroelectric Materials"
A. Yamaguchi, T. Ogasawara, Y. Utsumi, K. Yamada, A. Nakao

478

23rd International Colloquium on Magnetic Films and Surfaces (ICMFS 2018), UC Santa Cruz, USA,
July 22-27, 201839. "Study on magnetic characteristics modulated by Ferromagnetic/Ferro electric heterojunction"
A. Yamaguchi
The 34th International Conference of Photopolymer Science and Technology
9th JEMS Conference 2018, Mainz, Germany, September 3-7, 201840. "Ferromagnetic resonance study on Ni wire"
Akinobu Yamaguchi
The 34th International Conference of Photopolymer Science and Technology
Micro Nano Engineering 2018, Copenhagen, Denmark, September 24-27, 201841. "Study on surface acoustic wave actuator utilizing gravity for feeding various kinds ofmicro-powders"T. Saiki, K. Iimura, A. Yamaguchi, M. Takeo, Y. Utsumi, M. Suzuki
Micro Nano Engineering 2018, Copenhagen, Denmark, September 24-27, 201842. "Study on fabrication system of 3D printing or additive manufacturing process using X-ray
radiolysis"
A. Yamaguchi, I. Sakurai, I. Okada, A. Yamaguchi, M. Ishihara, T. Fukuoka, S. Suzuki, Y. Utsumi
Micro Nano Engineering 2018, Copenhagen, Denmark, September 24-27, 201843. "Characteristics of new deep X-ray lithography beamline (BL11) at new SUBARU"
Masaya Takeuchi, Akinobu Yamaguchi, Yuichi Utsumi
JCK MEMS/NEMS 2018 Conference, Dalian, China, July 13-15, 201844. "Anisotropic pyrochemical etching of PTFE induced by synchrotron radiation irradiation"
Masaya Takeuchi, Akinobu Yamaguchi, and Yuichi Utsumi
29th Micromechanics and Microsystems Europe Workshop, 28, Smolenice, Slovakia, August 26-29, 2018579

(3) Academic degrees
Master of Engineering
Yuta Kajino (University of Hyogo)
放射光利用光電子分光法によるアルミニウムの腐食進行に関する研究"Aluminum Erosion Analysis Using HAXPES at SPring-8 BL24XU "Fuki Sato (University of Hyogo)
NewSUBARU BL3 における EUV～VUV 領域用反射率計の開発"Development of Reflectometer in EUV – VUV Wavelength Region at NewSUBARU BL-03A"
Shota Niihara (University of Hyogo)
高感度 EUV レジスト開発のための軟Ｘ線評価手法の開発"Development of Evaluation Methods in Soft X-ray for High-Sensitive EUV Resis"

180