Papers - UMEZU Ikurou
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シリコンへの硫黄の過飽和ドーピングがもたらす光学的・電気的特性の変化 Reviewed
川本 兼司, 香野 淳,青木 珠緖,梅津 郁朗
電気学会論文誌 C(電子・情報・システム部門誌) 144 1066 - 1070 2024.11
Authorship：Corresponding author
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パルスレーザアブレーション法による可視光応答型プラズモニック光触媒の創製 Reviewed
電気学会論文誌 C(電子・情報・システム部門誌) 144 1100 - 1103 2024.11
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Study on Collision Process of Opposing Unsteady Supersonic Jets and Shock Waves Reviewed
Sakira Uno, Hiroshi Fukuoka, Atsushi Suda, Ikurou Umezu
Open Journal of Fluid Dynamics 13 ( 2 ) 104 - 112 2023.5
Authorship：Last author Publisher：Scientific Research Publishing, Inc.
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Mixing of laser‐induced plumes colliding in a background gas Reviewed
Keita Katayama,Toshiki Kinoshita,Ren Okada,Hiroshi Fukuoka,Takehito Yoshida,Minoru Yaga,Tamao Aoki‐Matsumoto, Ikurou Umezu
Applied Physics A 128 2022.10
Authorship：Last author, Corresponding author
We collided silicon and germanium laser-induced plumes in helium background gas to clarify the behavior of the plumes after the collision. The expansion of the silicon and germanium species in the mixed plume after the collision was observed separately by spectroscopic measurements and the degree of mixing was evaluated by the experimental results. When the pressure of the background gas was 2000 Pa, the plumes moved backward after the collision with the counter-propagating shock wave, and no mixing of the plumes was observed. The effect of the counter-propagating shock wave was discussed by comparing with the results of numerical calculations based on the compressible Euler equations. At 300 Pa, the plumes concentrated at about 1 mm around the central region just after the collision and almost 100% mixing occurred in this region. The concentration and mixing of the plumes in the central region is a key to forming well-mixed plume. Stagnation and partial mixing of the plumes were observed at intermediate pressures. By decreasing the background helium gas pressure from 2000 to 300 Pa, the degree of mixing increased from 0 to about 100%. The results are compared with those in argon background gas to discuss effects of mean free path. The effects of counter-propagating shock wave, mean free path and the onset time of the collision on the backward movement and mixing of the plumes are discussed.
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リアルタイムオンライン指導により学生自身が自宅で行う実験・実習 Reviewed
市田 正夫, 青木 珠緖, 秋宗 秀俊, 梅津 郁朗
物理教育 69 ( 4 ) 257 - 264 2021
Authorship：Last author
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学生実験の作業化への懸念と対応 Reviewed
梅津郁朗、青木珠緖、市田正夫、山﨑篤志、山本常夏
物理教育 68 268 - 272 2020.12
Joint Work
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Expansion of laser-induced plume after the passage of a counter shock wave through a background gas Reviewed
Akira Higo, Keita Katayama, Hiroshi Fukuoka, Takehito Yoshida, Tamao Aoki, Minoru Yaga, Ikurou Umezu
Applied Physics A 126 ( 4 ) 2020.3
Joint Work
Authorship：Last author, Corresponding author Publisher：Springer Science and Business Media LLC
DOI： 10.1007/s00339-020-03476-8
Other Link： http://link.springer.com/article/10.1007/s00339-020-03476-8/fulltext.html
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Effect of counter shock wave on the expanding plume Reviewed
Katayama Keita, Horai Yuki, Fukuoka Hiroshi, Kinoshita Toshiki, Yoshida Takehito, Aoki Tamao, Umezu Ikurou
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 124 ( 2 ) 2018.2
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Numerical Analysis of Behavior on Opposing Unsteady Supersonic Jets in a Flow Field with Shields Reviewed
Toshiki Kinoshita, Hiroshi Fukuoka, Ikurou Umezu
Materials Science Forum 910 96 - 101 2018.1
Joint Work
Authorship：Last author Publisher：Trans Tech Publications, Ltd.
Collision dynamics of opposing unsteady supersonic jets injected in background gas with shock waves were calculated to simulate double pulsed laser ablation. Since the jets are deflected by collision and the motion of debris is ballistic. This characteristic can be used to reduce the number of debris when shields are mounted in front of substrate. The flow of jets through installed shields is complicated by the interaction between shields and jets, and between shields and shock waves. We investigate influence of shield position on the shock waves and the jets by numerical calculations. Axisymmetric two-dimensional compressible Euler equations were solved using the finite volume method by using ANSYS Fluent 14.0.0 code. The shields with slit was mounted parallel to the direction of initially injected jets. In order to investigate the influence of shield position on the shock waves and the jets, the shield position and background gas pressure were adopted as parameters. The jets and shock wave are deflected by collision and they can pass through the slit of shields. The passed shock wave reflects at the substrate mounted behind the slits and it forces back the jet to decrease the jet velocity. The shield position governs the velocity and amount of the jet that reach the substrate.
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Lasing in organic mixed-crystal thin films with cavities composed of naturally formed cracks Reviewed
Mantoku Masaaki, Ichida Masao, Umezu Ikurou, Sugimura Akira, Aoki-Matsumoto Tamao
OPTICS LETTERS 42 ( 8 ) 1528 - 1531 2017.4
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e-beam irradiation effects on IR absorption bands in single-walled carbon nanotubes Reviewed
Ichida Masao, Nagao Katsunori, Ikemoto Yuka, Okazaki Toshiya, Miyata Yasumitsu, Kawakami Akira, Kataura Hiromichi, Umezu Ikurou, Ando Hiroaki
SOLID STATE COMMUNICATIONS 250 119 - 122 2017.1
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Hierarchical Structure of TiO2 Nano-Aggregates Prepared by Pulsed Laser Ablation in Background Gas Reviewed
Umezu Ikurou, Yoshida Takehito
ELECTRONICS AND COMMUNICATIONS IN JAPAN 99 ( 10 ) 40 - 45 2016.10
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Pulsed-laser-deposited TiO2 nanocrystalline films supporting Au nanoparticles for visible-light-operating plasmonic photocatalysts
Yoshida Takehito, Watanabe Tei, Kikuchi Fumito, Tabuchi Takeru, Umezu Ikurou, Haraguchi Masanobu
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 122 ( 5 ) 2016.5
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Dynamics of colliding laser ablation plumes in background gas Reviewed
Umezu Ikurou, Hashiguchi Yusuke, Fukuoka Hiroshi, Sakamoto Naomichi, Aoki Tamao, Sugimura Akira
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 122 ( 4 ) 2016.4
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Pulsed-laser-deposited TiO2 nanocrystalline films supporting Au nanoparticles for visible-light-operating plasmonic photocatalysts Reviewed
Yoshida, T., Watanabe, T., Kikuchi, F., Tabuchi, T., Haraguchi, M.
Applied Physics A 122 ( 5 ) 37 2016
Joint Work
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Pulsed laser irradiation-induced microstructures in the Mn ion implanted Si Reviewed
Naito Muneyuki, Yamada Ryo, Machida Nobuya, Koshiba Yusuke, Sugimura Akira, Aoki Tamao, Umezu Ikurou
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 365 110 - 113 2015.12
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Crossover from Efros-Shklovskii variable range hopping to nearest-neighbor hopping in silicon nanocrystal random network Reviewed
Inada Mitsuru, Yamamoto Hiroshi, Gibo Manabu, Ueda Rieko, Umezu Ikurou, Tanaka Shukichi, Saitoh Tadashi, Sugimura Akira
APPLIED PHYSICS EXPRESS 8 ( 10 ) 2015.10
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Correlation between crystallinity and mid-infrared optical absorption spectra of silicon supersaturated with sulfur Reviewed
Katsuki Nagao, Tatsuya Nakai, Muneyuki Naito, Mitsuru Inada, Tadashi Saitoh, Tamao Aoki and Akira Sugimura
MRS Proceedings 1738 mrsf14–1738–v14–05 2015
Joint Work
Authorship：Lead author
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ガス中パルスレーザアブレーションで作製された TiO2 ナノ粒子凝集体の階層構造 Reviewed
吉田 岳人
電気学会論文誌 C(電子・情報・システム部門誌) 135 ( 9 ) 1055 2015
Joint Work
Authorship：Lead author
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Hyperdoping of silicon with deep-level impurities by pulsed YAG laser melting
Umezu Ikurou, Naito Muneyuki, Kawabe Daisuke, Koshiba Yusuke, Nagao Katsuki, Sugimura Akira, Aoki Tamao, Inada Mitsuru, Saitoh Tadashi, Kohno Atsushi
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 117 ( 1 ) 155 - 159 2014.10
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Structural properties of TiO2 nanocrystallites condensed in vapor-phase for photocatalyst applications
Yoshida Takehito, Yagi Nobuyasu, Nakagou Riki, Sugimura Akira, Umezu Ikurou
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 117 ( 1 ) 223 - 227 2014.10
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Hyperdoping of silicon with deep-level impurities by pulsed YAG laser melting. Reviewed
Naito, M., Kawabe, D., Koshiba, Y., Nagao, K., Sugimura, A., Aoki, T., Inada, M., Saitoh, T., & Kohno, A
Applied Physics A 117 155 - 159 2014
Joint Work
Authorship：Lead author
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Hyperdoping of silicon with deep-level impurities by pulsed YAG laser melting Reviewed
Naito, M., Kawabe, D., Koshiba, Y., Nagao, K., Sugimura, A., Aoki, T., Inada, M., Saitoh, T., & Kohno, A
Applied Physics A 117 155 - 159 2014
Single Work
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Structural properties of TiO2 nanocrystallites condensed in vapor-phase for photocatalyst applications. Reviewed
Yoshida, T., Yagi, N., Nakagou, R., Sugimura, A.
Applied Physics A 117 223 - 227 2014
Single Work
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Emergence of very broad infrared absorption band by hyperdoping of silicon with chalcogens
Umezu Ikurou, Warrender Jeffrey M., Charnvanichborikarn Supakit, Kohno Atsushi, Williams James S., Tabbal Malek, Papazoglou Dimitris G., Zhang Xi-Cheng, Aziz Michael J.
JOURNAL OF APPLIED PHYSICS 113 ( 21 ) 2013.6
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Effects of collision between two plumes on plume expansion dynamics during pulsed laser ablation in background gas
Umezu Ikurou, Sakamoto Naomichi, Fukuoka Hiroshi, Yokoyama Yasuhiro, Nobuzawa Koichiro, Sugimura Akira
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 110 ( 3 ) 629 - 632 2013.3
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Growth Processes of Porous TiO2 Nanocrystal-films during Pulsed Laser Ablation. Reviewed
I., Yagi, N., Sugimura, A., & Yoshida, T.
MRS Proceedings 1497 mrsf12–1497–k03–20 2013
Joint Work
Authorship：Lead author
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Fluid simulation of plume head-on collision dynamics during pulsed laser ablation Reviewed
Fujii, R., Doi, K., Yokoyama, Y., Fukuoka, H., Sugimura, A., Tominaga, N
J. Phys.: Conf. Ser. 454 012009 2013
Joint Work
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Emergence of very broad infrared absorption band by hyperdoping of silicon with chalcogens Reviewed
I., Warrender, J. M., Charnvanichborikarn, S., Kohno, A., Williams, J. S., Tabbal, M., Papazoglou, D. G., Zhang, X.-C., & Aziz, M. J.
Journal of Applied Physics, 113 ( 21 ) 213501 2013
Joint Work
Authorship：Lead author
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Hierarchical Pattern Structure in TiO2 Nano-Aggregates Prepared by Pulsed Laser Ablation in Background Gas
2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS PACIFIC RIM (CLEO-PR) 2013
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Fluid simulation of plume head-on collision dynamics during pulsed laser ablation
24TH IUPAP CONFERENCE ON COMPUTATIONAL PHYSICS (IUPAP-CCP 2012) 454 2013
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パルスレーザーメルティング法によって深い準位をとる不純物を過飽和ドープしたシリコンの赤外光吸収
梅津 郁 朗, 香 野 淳, 川 邊 大介, 松田 祐樹, 中川 将, and 杉村 陽
電気学会研究会資料 光・量子デバイス研究会 QD12 47 - 50 2012.3
Joint Work
Authorship：Lead author
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Low Temperature Bonding of Metals by Deposition of Nanoparticles at the Interface Reviewed
Toshio Takiya, Naoaki Fukuda, Ikurou Umezu, Akira Sugimura, Shigeo Ueguri, Hisao Yoshida, and Min Han
Applied Physics Research 4 42 - 47 2012.2
Joint Work
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Effects of collision between two plumes on plume expansion dynamics during pulsed laser ablation in background gas Reviewed
Sakamoto, N., Fukuoka, H., Yokoyama, Y., Nobuzawa, K., & Sugimura, A
Appl Phys A 110 ( 3 ) 629 - 632 2012
Joint Work
Authorship：Lead author
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Effects of collision between two plumes on plume expansion dynamics during pulsed laser ablation in background gas Reviewed
Sakamoto, N., Fukuoka, H., Yokoyama, Y., Nobuzawa, K., & Sugimura, A
Appl. Phys. A 110 ( 3 ) 629 - 632 2012
Joint Work
Authorship：Lead author
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Supersaturated doping of silicon with titanium by pulsed laser melting method
Daisuke Kawabel, Shou Nakagawa, Yuuki Matsudal, Akira Sugimura, and Ikurou Umezu
Mem. Konan Univ., Sci. & Eng. Ser. 58 ( 1 ) 21 - 32 2011.12
Joint Work
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Synthesis of GaN nanocrystallites by pulsed laser ablation in pure nitrogen background gases Reviewed
T Yoshida, S. Kakumoto, A Sugimura, and I Umezu
Applied Physics A: Materials Science & Processing 104 907 - 911 2011.9
Joint Work
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Photoluminescence from Excited Energy Bands in Au-25 Nanoclusters
Sakanaga Isamu, Inada Mitsuru, Saitoh Tadashi, Kawasaki Hideya, Iwasaki Yasuhiko, Yamada Toshiki, Umezu Ikurou, Sugimura Akira
APPLIED PHYSICS EXPRESS 4 ( 9 ) 2011.9
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Synthesis of GaN nanocrystallites by pulsed laser ablation in pure nitrogen background gases
Yoshida Takehito, Kakumoto Soichiro, Sugimura Akira, Umezu Ikurou
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 104 ( 3 ) 907 - 911 2011.9
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Photoluminescence from Excited Energy Bands in Au$_{25}$ Nanoclusters Reviewed
Isamu Sakanaga, Mitsuru Inada, Tadashi Saitoh, Hideya Kawasaki, Yasuhiko Iwasaki, Toshiki Yamada, Ikurou Umezu, and Akira Sugimura
Appl. Phys. Express 4 095001-1 - 095001-3 2011.8
Joint Work
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Strong mid-infrared optical absorption emerged by supersaturated sulfur doping in silicon wafer Reviewed
I. Umezu, A. Kohno, J. M. Warrender, Y. Takatori, Y.Hirao, S. Nakagawa, A. Sugimura, S. Charnvanichborikarn, J. S. Williams and M. J. Aziz
Proceedings of 30th International Conference on the Physics of Semiconductors 1399 51 - 52 2011.1
Single Work
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Effect of Non-equilibrium Pulsed Ejection of Si Species into Background Gas on the Formation of Si Nanocrystallite Reviewed
Ikurou Umezu, Shunto Okubo , Akira Sugimura
Mater. Res. Soc. Symp. Proc. 1035 2011.1
Joint Work
Authorship：Lead author
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Development of precise tuning method of inter-dot spacing and resonant energy transfer between Au clusters
Inada Mitsuru, Yoshihara Yoshihiro, Kawasaki Hideya, Iwasaki Yasuhiko, Saitoh Tadashi, Umezu Ikurou, Sugimura Akira
NANOPHOTONIC MATERIALS VIII 8094 2011
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Roles of SiH4 in Growth, Structural Changes and Optical Properties Of Nanocrystalline Silicon Thin Films
Ali A. M., Inokuma T., Al-Hajry A., Kobayashi H., Umezu I., Morimoto A.
PROCEEDINGS OF THE FIFTH SAUDI PHYSICAL SOCIETY CONFERENCE (SPS5) 1370 2011
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Strong mid-infrared optical absorption by supersaturated sulfur doping in silicon
Umezu I., Kohno A., Warrender J. M., Takatori Y., Hirao Y., Nakagawa S., Sugimura A., Charnvanichborikarn S., Williams J. S., Aziz M. J.
PHYSICS OF SEMICONDUCTORS: 30TH INTERNATIONAL CONFERENCE ON THE PHYSICS OF SEMICONDUCTORS 1399 2011
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Effect of non-equilibrium pulsed ejection of Si species into background gas on the formation of Si nanocrystallite and nanocrystal-film
Ikurou Umezu, Shunto Okubo, Akira Sugjmura
Materials Research Society Symposium Proceedings 1305 13 - 18 2011
Joint Work
The Si nanocrystal-films are prepared by pulsed laser ablation of Si target in a mixture of helium and hydrogen gas. The total gas pressure and hydrogen partial gas pressure were varied to control structure of nanocrystal-film. The surface of Si nanocrystallite was hydrogenated and degree of hydrogenation increased with increasing hydrogen partial gas pressure. The aggregate structure of nanocrystal-film depended on both the total gas pressure and the hydrogen partial gas pressure. The former and the latter alter spatial confinement of Si species during deposition and the surface hydrogenation of individual nanocrystal, respectively. Spatial confinement increases probability of collision between nanocrystals in the plume. While, surface hydrogenation prevents coalescence of nanocrystals. The individual or aggregated nanocrystals formed in the plume reach the substrate and the nanocrystal-film is deposited on the substrate. The non-equilibrium growth processes duringpulsed laser ablation are essential for the formation of the surface structure and the subsequent nanocrystal-film growth. Our results indicate that the structure of nanocrystal-film depends on the probabilities of collision and coalescence between nanocrystals in the plume. These probabilities can be varied by controlling the total gas pressure and the hydrogen partial gas pressure. © 2011 Materials Research Society.
DOI： 10.1557/opl.2011.87
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Fabrication and Sub-Bandgap Optical Properties of Silicon Supersaturated with Chalcogens by Ion Implantation and Pulsed Laser Melting Reviewed
Fabrication and Sub-Bandgap Optical Properties of Silicon Supersaturated with Chalcogens by Ion Implantation and Pulsed Laser Melting
B. P. Bob, A. Kohno, S. Charnvanichborikarn, J. M. Warrender, I. Umezu, M. Tabbal, J. S. Williams and M. J. Aziz 107 123506 2010.11
Joint Work
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ガス中パルスレーザアブレーションでのSiナノ構造の生成過程に対するパルス励起の効果
梅津郁朗
レーザ加工学会誌 17 93 2010.11
Single Work
Authorship：Lead author
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Inter-Dot Distance Dependence of Photoluminescence Properties in CdSe Quantum Dot Systems
K. Tai, W. Lü, I. Umezu and A. Sugimura
Appl. Phys. Express 3 035202 2010.11
Joint Work
Authorship：Lead author
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Emission induced by collision of two plumes during pulsed laser ablation Reviewed
I. Umezu, S. Yamamoto and A. Sugimura
Applied Physics A: Materials Science & Processing 101 133 - 136 2010.11
Joint Work
Authorship：Lead author
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Formation of core-shell structured silicon nanoparticles during pulsed laser Ablation Reviewed
I. Umezu, Y. Nakayama and A. Sugimura
J. Appl. Phys. 2010.11
Joint Work
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Emission induced by collision of two plumes during pulsed laser ablation
Umezu Ikurou, Yamamoto Shigeki, Sugimura Akira
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 101 ( 1 ) 133 - 136 2010.10
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Fabrication and subband gap optical properties of silicon supersaturated with chalcogens by ion implantation and pulsed laser melting
Bob Brion P., Kohno Atsushi, Charnvanichborikarn Supakit, Warrender Jeffrey M., Umezu Ikurou, Tabbal Malek, Williams James S., Aziz Michael J.
JOURNAL OF APPLIED PHYSICS 107 ( 12 ) 2010.6
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Formation of core-shell structured silicon nanoparticles during pulsed laser ablation
Umezu Ikurou, Nakayama Yusuke, Sugimura Akira
JOURNAL OF APPLIED PHYSICS 107 ( 9 ) 2010.5
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Inter-Dot Distance Dependence of Photoluminescence Properties in CdSe Quantum Dot Systems
Tai Kohei, Lue Wei, Umezu Ikurou, Sugimura Akira
APPLIED PHYSICS EXPRESS 3 ( 3 ) 2010
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Synthesis of Ni-doped InTaO4 nanocrystallites by reactive pulsed laser ablation for application to visible-light-operating photocatalysts Reviewed
Takehito Yoshida, Hirokazu Toyoyama, I Umezu, Akira Sugimura
Applied surface science 255 9634 - 9637 2009.11
Joint Work
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Trap state emission of water-soluble CdS nanocrystals Reviewed
W Lü, Y Tokuhiro, I Umezu, A Sugimura, Y Nagasaki
phys. stat. sol. (c) 6 346 - 349 2009.11
Joint Work
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Synthesis of Ni-doped InTaO4 nanocrystallites by reactive pulsed laser ablation for application to visible-light-operating photocatalysts
Yoshida Takehito, Toyoyama Hirokazu, Umezu Ikurou, Sugimura Akira
APPLIED SURFACE SCIENCE 255 ( 24 ) 9634 - 9637 2009.9
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Fluorescence Resonance Energy Transfer and Concentration Quenching Effect in CdSe Quantum Dot System
Kohei Tai, Wei Lu, Ikurou Umezu, A Sugimura
Mem. konan Univ. , Sci. &Eng Ser. 56 11 2009.4
Joint Work
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Effect of Phosphorus Ion Doping for Silicon Nanocrystal Assembly
Kei Hirata, Manabu Gibo, Kenichi Yoshida, Mitsuru Inuda, Ikurou Umezu, Shinji Nagamachi, Tadashi Saitoh, Akira Sugimura
Mem. konan Univ. , Sci. & Eng Ser. 56 2009.4
Joint Work
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Simulation of effect of pulse width on super saturated doping by pulsed laser melting method
Shou Nakagawa, Ikurou Umezu, Akira Sugimura
Mem. konan Univ. , Sci. & Eng Ser. 56 1 2009.4
Joint Work
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Trap state emission of water-soluble CdS nanocrystals
W. Lü, Y. Tokuhiro, I. Umezu, A. Sugimura, Y. Nagasaki
Physica Status Solidi (C) Current Topics in Solid State Physics 6 ( 1 ) 346 - 349 2009
Joint Work
We prepared water-soluble CdS nanocrystals (NCs) capped by the poly (ethylene glycol)b-poly (2-(N,N-dimethylammojethyl methacrylate) chain. The photoluminescence (PL) properties of CdS NCs are investigated by time-resolved and temperature-dependent PL spectra. It IB found that the PL band of CdS NCs is dominated by two trap state emissions, respectively. Due to the trap state emissions, fluorescent resonance energy transfer from CdS NCs to organic dyes (Texasred) can be observed, which suggests the potential application of trap states of CdS NCs for fabrication of biosensors. © 2009 WILEY-VCH Verlag GmbH &
Co. KGaA. -
InTaO4-based nanostructures synthesized by reactive pulsed laser ablation
Yoshida Takehito, Toyoyama Hirokazu, Umezu Ikurou, Sugimura Akira
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 93 ( 4 ) 961 - 966 2008.12
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Oxidation processes of surface hydrogenated silicon nanocrystallites prepared by pulsed laser ablation and their effects on the photoluminescence wavelength （共著）
I. Umezu, A. Sugimura, T. Makino, M. Inada and K. Matsumoto
J. Appl. Phys. 2008.11
Joint Work
Authorship：Lead author
J. Appl. Phys. 103, (2008) 024305
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Collective Transport in Silicon Nanocrystal Assembly Prepared by Laser Ablation Method Reviewed
Akira Sugimura, Manabu Gibo, Mitsuru Inada, Tadashi Saitoh, I Umezu
Mater. Res. Soc. Symp. Proc. 1145 2008.11
Joint Work
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Evolution of Energy Transfer Process between Quantum Dots of Two Different Sizes during the Evaporation of Solvent Reviewed
W. Lu, I Umezu, A Sugimura
Japanese Journal of Applied Physics 47 6592 - 6595 2008.11
Joint Work
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Oxidation processes of surface hydrogenated silicon nanocrystallites prepared by pulsed laser ablation and their effects on the photoluminescence wavelength Reviewed
Ikurou Umezu, Toshiharu Makino, Mitsuru Inada, Kimihisa Matsumoto, Akira Sugimura
Journal of Applied Physics 103 024305 2008.11
Joint Work
Authorship：Lead author
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Interfacial strain effects on optical response of CdSe/ZnS core/shell quantum dots
W Lu, I Umezu, A Sugimura
Mem.Konan Unive.Sci&Eng 53 153 - 161 2008.11
Joint Work
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Collective transport in silicon nanocrystal assembly Reviewed
Manabu Gibo, Mitsuru Inada, Tadashi Saitoh, Ikurou Umezu, Akira Sugimura
Proceedings of The International Meeting for Future of Electron Devices 2008 115 - 116 2008.11
Joint Work
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Direct observation of resonance energy transfer between two different sized quantum dots Reviewed
W Lü, I Umezu, A Sugimura
Proceeding of the 2nd Thailand Nanotechnology Conference 2008.11
Joint Work
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Surface hydrogenation of silicon nanocrystallites during pulsed laser ablation of silicon target in hydrogen background gas Reviewed
Ikurou Umezu, Masatoshi Takata, Akira Sugimura
J. Appl. Phys 103 11309 2008.11
Joint Work
Authorship：Lead author
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Formation of surface stabilized Si nanocrystal by pulsed laser ablation in hydrogen gas Reviewed
Ikurou Umezu, Issei Kondo, Akira Sugimura
Applied Physics A 93 717 - 720 2008.11
Joint Work
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InTaO4-based nanostructures synthesized by reactive pulsed laser ablation Reviewed
Takehito Yoshida, Hirokazu Toyoyama, Ikurou Umezu, Akira Sugimura
Applied Physics A 93 961 - 966 2008.11
Joint Work
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Formation of surface stabilized Si nanocrystal by pulsed laser ablation in hydrogen gas
Umezu Ikurou, Kondo Issei, Sugimura Akira
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 93 ( 3 ) 717 - 720 2008.11
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Evolution of Energy Transfer Process between Quantum Dots of Two Different Sizes during the Evaporation of Solvent
Lue Wei, Umezu Ikurou, Sugimura Akira
JAPANESE JOURNAL OF APPLIED PHYSICS 47 ( 8 ) 6592 - 6595 2008.8
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Surface hydrogenation of silicon nanocrystallites during pulsed laser ablation of silicon target in hydrogen background gas
Umezu Ikurou, Takata Masatoshi, Sugimura Akira
JOURNAL OF APPLIED PHYSICS 103 ( 11 ) 2008.6
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Oxidation processes of surface hydrogenated silicon nanocrystallites prepared by pulsed laser ablation and their effects on the photoluminescence wavelength
Umezu Ikurou, Sugimura Akira, Makino Toshiharu, Inada Mitsuru, Matsumoto Kimihisa
JOURNAL OF APPLIED PHYSICS 103 ( 2 ) 2008.1
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Study of energy transfer in mixed system of two different sized quantum dots
Wei Lü, I Umezu, Akira Sugimura
Trends in NanoTechnology- TNT2007 2007.11
Joint Work
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Formation of nanoscale fine-structured silicon by pulsed laser ablation in hydrogen background gas Reviewed
Ikurou Umezu, Akira Sugimura, Mitsuru Inada, Toshiharu Makino, Kimihisa Matsumoto, Masatoshi Takata
Phys. Rev. B 76 045328 2007.11
Joint Work
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Plume analysis during pulsed laser ablation of silicon in hydrogen gas Reviewed
M Takata, I Umezu, A Sugimura
J. Phys.: Conf. Ser. 59 575 - 578 2007.11
Joint Work
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Effects of surface oxidation on optical absorption of sillicon nanocrystallites Reviewed
Umezu and Koyama and Yoshida and Sugimura
Proceedings of 28th international conference on the physics of semiconductors 2007.11
Joint Work
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Nanoparticle formation in the expansion process of a laser ablated plume
M Takiya, I Umezu, M Yaga, M Han
J. Phys.: Conf. Ser. 59 445 - 448 2007.11
Joint Work
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Electron transport in hydrogen-passivated silicon nanochains prepared by pulsed laser ablation
H Yamamoto, M Inada, R Ueda, I Umezu, S tanaka, T Saitoh, A Sugimura
Mem. konan Univ. , Sci. Ser. 54 89 - 103 2007.11
Joint Work
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Interaction effect among silicon nanocrystallites caused by aggregation structure
I Kondo, I Umezu, A Sugimura
Mem. konan Univ. , Sci. Ser. 54 105 - 117 2007.11
Joint Work
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Fractal growth of silicon nanocrystallites during pulsed laser ablation Reviewed
I Umezu, M Inada, T Makino, A Sugimura
Proceedings of 28th international conference on the physics of semiconductors 2007.11
Joint Work
Authorship：Lead author
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Mechanism of Electron-Hole Pair Generation and Light Emission for Electro-Luminescence Devices with Silicon Nano-Crystals Prepared by Laser Ablation Method
Sugimura and Koyama and Inada and Yoshida and Umezu
Proceedings of 28th international conference on the physics of semiconductors 2007.11
Joint Work
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Excitation energy transfer based on trap states of CdS quantum dots Reviewed
Wei Lü, Ikurou Umezu, Akira Sugimura
Nanoinsight 2007 international conference 2007.11
Joint Work
-
Synthesis of photoluminescent colloidal silicon nanoparticles by pulsed laser ablation in liquids Reviewed
I Umezu, H Minami, H Senoo, A Sugimura
Journal of Physics: Conference Series 59 2007.11
Joint Work
Authorship：Lead author
-
Formation of nanoscale fine-structured silicon by pulsed laser ablation in hydrogen background gas
Umezu Ikurou, Sugimura Akira, Inada Mitsuru, Makino Toshiharu, Matsumoto Kimihisa, Takata Masatoshi
PHYSICAL REVIEW B 76 ( 4 ) 2007.7
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Effect of surface oxidation on optical absorption of silicon nanocrystallites
Umezu Ikurou, Koyama Motohiko, Yoshida Takehito, Sugimura Akira
PHYSICS OF SEMICONDUCTORS, PTS A AND B 893 895 - + 2007
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Fractal growth of silicon nanocrystaffites during pulsed laser ablation
Umezu Ikurou, Inada Masuru, Makino Toshiharu, Sugimura Akira
PHYSICS OF SEMICONDUCTORS, PTS A AND B 893 43 - + 2007
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Mechanism of electron-hole pair generation and light emission for electro-luminescence devices with silicon nano-crystals prepared by laser ablation method
Sugimura A., Koyama M., Inada M., Yoshida T., Umezu I.
PHYSICS OF SEMICONDUCTORS, PTS A AND B 893 1433 - + 2007
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Synthesis of photoluminescent colloidal silicon nanoparticles by pulsed laser ablation in liquids
Umezu I., Minami H., Senoo H., Sugimura A.
COLA'05: 8TH INTERNATIONAL CONFERENCE ON LASER ABLATION 59 392 - + 2007
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Plume analysis during pulsed laser ablation of sillicon in hydrogen gas
Takata M., Umezu I., Sugimura A.
COLA'05: 8TH INTERNATIONAL CONFERENCE ON LASER ABLATION 59 575 - + 2007
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Nanoparticle formation in the expansion process of a laser ablated plume
Takiya T., Umezu I., Yaga M., Han M.
COLA'05: 8TH INTERNATIONAL CONFERENCE ON LASER ABLATION 59 445 - + 2007
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Resonance energy transfer based on shallow and deep energy levels of biotin-po lyethylene glycol/polyamine stabilized CdS quantum dots.（共著）
W. Lu; , Y. Tokuhiro, I. Umezu and A. Sugimura, Y. Nagasaki.
Applied Physics Letters, 89 ( 143901 ) 1 - 3 2006.11
Joint Work
Applied Physics Letters, Vol.89, 143901, pp.1-3. (2006)
-
Size-dependent optical properties of CdSe/ZnS core/shell quantum dots
W Lü, I Umezu, A Sugimura
Mem. Konan Univ., Sci. & Eng. Ser. 53 151 - 163 2006.11
Joint Work
-
Resonance energy transfer based on shallow and deep energy levels of biotin-polyethylene glycol/polyamine stabilized CdS quantum dots
Lu W., Tokuhiro Y., Umezu I., Sugimura A., Nagasaki Y.
APPLIED PHYSICS LETTERS 89 ( 14 ) 2006.10
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Effects of surface adsorption on the photoluminescence wavelength of silicon nanocrystal
Umezu I, Kimura T, Sugimura A
PHYSICA B-CONDENSED MATTER 376 853 - 856 2006.4
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Spatial fluctuation enhancement and nonradiative-recombination-center generation due to high Si-doping into GaAs/A1As short-period-superlattices
Kobori H, Shigetani A, Umezu I, Sugimura A
PHYSICA B-CONDENSED MATTER 376 861 - 863 2006.4
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Localization and transport of type-II excitons in spatially enhanced random potential for highly Si-doped GaAs/AlAs short-period-superlattices
Kobori H., Shigetani A., Umezu I., Sugimura A.
LOW TEMPERATURE PHYSICS, PTS A AND B 850 1520 - + 2006
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Unusual behavior on line-broadening of photoluminescence spectrum for type-II excitons in highly Si-doped GaAs/AlAs short-period-superlattices
Kobori H., Shigetani A., Umezu I., Sugimura A.
LOW TEMPERATURE PHYSICS, PTS A AND B 850 1522 - + 2006
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Correlation between natural oxidation process and photoluminescence properties of hydrogenated Si nanocrystallites prepared by pulsed laser ablation
Matsumoto K, Inada M, Umezu I, Sugimura A
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 44 ( 12 ) 8742 - 8746 2005.12
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A correlation between natural oxidation process and PL properties of hydrogenated Si nanocrystallites prepared by pulsed laser ablation. （共著）
K. Matsumoto, M. Inada, I. Umezu and A. Sugimura.
Jpn. J. Appl. Phys. 44, 8742 - 8746 2005.11
Joint Work
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Correlation between PL emission band and growth of oxide layer on surface of silicon nanocrystallites（共著）
I. UMEZU, M. Koyama, T. Hasegawa, K. Matsumoto, M. Inada and A. Sugimura.
AIP conference proceedings (The Proceedings of the 27th International Conference on the Physics of Semiconductors) 772, 855 - 856 2005.11
Joint Work
Authorship：Lead author
-
Correlation between electronic structure and chemical bond on the surface of hydrogenated silicon nanocrystallites. （共著）
I. UMEZU, T. Makino, M. Takata, M. Inada and A. Sugimura.
AIP conference proceedings (The Proceedings of the 27th International Conference on the Physics of Semiconductors) 772, . 691 - 692 2005.11
Joint Work
Authorship：Lead author
-
Preparation of surface controlled silicon nanocrystallites by pulsed laser ablation. （共著）
I. UMEZU, M. Inada, T. Makino and A. Sugimura.
AIP conference proceedings (The Proceedings of the 27th International Conference on the Physics of Semiconductors) 772,. 861 - 862 2005.11
Joint Work
Authorship：Lead author
-
Considereable enhancement of PL intensity for free exciton in ZnO ultra-fine-particles and oscillatory green band emergence in PL spectrum for Cu-doped ZnO ultra-fine particles with heat treatment. （共著）
H. Kobori, T. Nanao, S. Kawaguchi, I. Umezu and A. Sugimura.
The Proceedings of the 27th International Conference on the Physics of Semiconductors 867 - 868 2005.11
Joint Work
-
"Temperature dependence of time-resolved luminescence spectra for 1D excitons in single-walled carbon nanotubes in micelles. （共著）
M. Ichida, I. Umezu, H. Kataura, M. Kimura, S. Suzuki, Y. Achiba and H. Ando.
Journal of Luminescence 112, 287 - 290 2005.11
Joint Work
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Formation of Hydrogen-passivated silicon Nanochains by Pulsed laser Ablation without Thermal Annealing
梅津郁郎
Mater. Res. Soc. Symp. Proc. 832, (2005)F7.24.1-F7.24.5. 2005.11
Single Work
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Structual and optical properties of surface-hydrogeneted silicon nanocrystallites prepeared by reactive pulsed laser ablation.（共著）
T.Makino,M.Inada,Umezu and A.Sugimura.
J. Phys. D 38, 3507 - 3511 2005.11
Joint Work
-
Structural and optical properties of surface-hydrogenated silicon nanocrystallites prepared by reactive pulsed laser ablation
Makino T, Inada M, Umezu I, Sugimura A
JOURNAL OF PHYSICS D-APPLIED PHYSICS 38 ( 18 ) 3507 - 3511 2005.9
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Temperature dependence of time-resolved luminescence spectra for ID excitons in single-walled carbon nanotubes in micelles
Ichida M, Umezu I, Kataura H, Kimura M, Suzuki S, Achiba Y, Ando H
JOURNAL OF LUMINESCENCE 112 ( 1-4 ) 287 - 290 2005.4
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Considerable enhancement of PL intensity for free exciton in ZnO ultra-fine-particles and oscillatory green band emergence in PL spectrum for Cu-doped ZnO ultra-fine-particles with heat treatment
Kobori H, Nanao T, Kawaguchi S, Umezu I, Sugimura A
Physics of Semiconductors, Pts A and B 772 867 - 868 2005
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Correlation between PL emission band and growth of oxide layer on surface of silicon nanocrystallites
Umezu I, Koyama M, Hasegawa T, Matsumoto K, Inada M, Sugimura A
Physics of Semiconductors, Pts A and B 772 855 - 856 2005
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Correlation between electronic structure and chemical bond on the surface of hydrogenated silicon nanocrystallites
Umezu I, Makino T, Takata M, Inada M, Sugimura A
Physics of Semiconductors, Pts A and B 772 691 - 692 2005
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Preparation of surface controlled silicon nanocrystallites by pulsed laser ablation
Umezu I, Inada M, Makino T, Sugimura A
PHYSICS OF SEMICONDUCTORS, PTS A AND B 772 861 - 862 2005
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Correlation between surface oxide and photoluminescence properties of Si nanoparticles prepared by pulsed laser ablation（共著）
I. Umezu, K. Matsumoto, M. Inada, T. Makino and A. Sugimura
Applied Physics A 79, 1545 - 1547 2004.11
Joint Work
Authorship：Lead author
-
Recombination process of CdS quantum dot covered by novel Polymer Chains（共著）
I. Umezu, R. Koizumi, A. Sugimoto, M. Inada, T. Makino, A. Sugimura, Y. Sunaga, T. Ishii and Y. Nagasaki
Physica E 21, 1102 - 1105 2004.11
Joint Work
Authorship：Lead author
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Optical and transport studies in coupled InAs quantum dots embedded in GaAs（共著）
M. Inada, I. Umezu, P. O. Vaccaro, S. Yamada and A. Sugimura
Physica E 21, 317 - 321 2004.11
Joint Work
-
Inter-dot electron transport in coupled InAs quantum dots under magnetic field（共著）
M. Inada, I. Umezu, P. O. Vaccaro, S. Yamada and A. Sugimura
Semicond. Sci. Technol. 19, 54 - 55 2004.11
Joint Work
Semicond. Sci. Technol. 19, (2004)S54-S55,
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Structural and optical properties of silicon nanoparticles prepared by pulsed laser ablation in hydrogen backgrond gas（共著）
T. Makino, M. Inada1, K. Yoshida, I. Umezu and A. Sugimura1
Applied Physics A to be, 2004.11
Joint Work
-
Optical Properties of CdS Nanocrystal Covered by Polymer Chains on the Surface（共著）
I. Umezu, K. Mandai, R. Koizumi, M. Inada, A. Sugimura, Y. Sunaga, T. Ishii and Y. Nagasaki
MicroElectronic Engineering 66, 53 - 58 2003.11
Single Work
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Observation of inter-dot electron transport via spin-split states in InAs quantum dots （共著）
M. Inada, S. Sato, I. Umezu, P. O. Vaccaro, S. Yamada and A. Sugimura.
(Institute of Physics Publishing, Bristol (UK)and Philadelphia (USA), 2003) Institute of Physics Conference Series Number 171 、H188,1-5. 2003.11
Single Work
-
Effects of hydroganation on photoluminescence of Si nanoparticles formed by pulsed laser ablation（共著）
M. Inada, H. Nakagawa, I. Umezu and A. Sugimura
Materials Science & Engineering B 101, 283 - 285 2003.11
Joint Work
-
Effect of gas pressure on reactive pulsed laser ablation of a silicon target（共著）
M. Inada, I. Umezu and A. Sugimura
J. Vac. Sci. Technol. A 21, 84 - 86 2003.11
Joint Work
-
Mechanizms of Visible Photoluminescence from Size-Controlled Silicon Nanoparticles（共著）
T. Makino, N. Suzuki, Y. Yamada, T. Yoshida, I. Umezu and A. Sugimura
Mat. Res. Soc. Symp. Proc. 737, 265 - 270 2003.11
Joint Work
-
Optical properties of CdS quantum dot covered by novel polymer chains（共著）
I Umezu, K.Mandai1, R. Koizumi1, M. Inada, A. Sugimura, Y. Sunaga, T. Ishii and Y. Nagasaki.
(Institute of Physics Publishing, Bristol (UK)and Philadelphia (USA), 2003) Institute of Physics Conference Series Number 171 、H202, 1-5, 2003.11
Joint Work
Authorship：Lead author
-
Correlation between structure and nonradiative recombination process in silicon nanocrystallites （共著）
I Umezu, M. Inada, H. Nakagawa, K. Matsumoto and A. Sugimura.
(Institute of Physics Publishing, Bristol (UK)and Philadelphia (USA), 2003) Institute of Physics Conference Series ，Number 171 D173, 1-5, 2003.11
Joint Work
Authorship：Lead author
-
Reaction between nitrogen gas and silicon species during pulsed laser ablation（共著）
I. Umezu, M. Inada, K. Kohno, T. Yamaguchi, T. Makino and A. Sugimura
J. Vac. Sci. Technol. A 21, 1680 - 1682 2003.11
Joint Work
Authorship：Lead author
-
Mechanisms of visible photoluminescence from size-controlled silicon nanoparticles
Makino T, Suzuki N, Yamada Y, Yoshida T, Umezu I, Sugimura A
QUANTUM CONFINED SEMICONDUCTOR NANOSTRUCTURES 737 265 - 270 2003
Joint Work
-
Preparation of SiNx film by pulsed laser ablation in nitrogen gas ambient（共著）
I. Umezu, T. Yamaguchi, K. Kohno, M. Inada and A. Sugimura
Appl. Surf. Sci. 197-198C, 314 - 316 2002.11
Joint Work
Authorship：Lead author
-
Deposition of silicon nitride films by pulsed laser ablation of Si target in nitrogen gas（共著）
I. Umezu, K. Kohno, T. Yamaguchi, A. Sugimura and M. Inada
J. Vac. Sci. and technol. A 20, (2002)30-32， 2002.11
Joint Work
Authorship：Lead author
-
Study of silicon nanocrystal prepared by pulsed laser ablation in H2 gas（共著）
K. Matsumoto, H. nakagawa, M. Inada, I. Umezu and A. Sugimura
Mem. Konan Univ., Sci. Ser. 49, (2002)17-23, 2002.11
Joint Work
-
Nano-oxidation of an amorphous silicon surface with an atomic force microscope（共著）
I. Umezu, T. Yoshida, K. Matsumoto, M. Inada and A. Sugimura
J. Noncryst. solids 299-302, (2002)1090-1094, 2002.11
Joint Work
Authorship：Lead author
-
Effects of hydrogen on Si nanoparticles formed by pulsed laser ablation（共著）
M. Inada, H. Nakagawa, I. Umezu and A. Sugimura
Applied surface science 197-198, (2002)666-669, 2002.11
Joint Work
-
Effect of Structure on Radiative Recombination Process in Amorphous Silicon Suboxide Prepared by RF Sputtering（共著）
K.-i. Yoshida, I. Umezu, N. Sakamoto, M. Inada and A. Sugimura
Journal of applied physics 92, 5936 - 5941 2002.11
Joint Work
-
Photoluminescence Properties of Amorphous Silicon-based Oxygen and Hydrogen Alloys（共著）
I. Umezu, K.-i. Yoshida, N. Sakamoto, T. Murota, Y. Takashima, M. Inada and A. Sugimura
J.Appl. Phys. 91, 2009 - 2014 2002.11
Joint Work
Authorship：Lead author
-
Effects of Argon and hydrogen plasmas on the surface of silicon（共著）
I. Umezu, K. Kohno, K. Aoki, Y. Kohama, A. Sugimura and M. Inada
Vacuum 66/3-4, 453 - 456 2002.11
Joint Work
Authorship：Lead author
-
Nanoscale anodization of an amorphous silicon surface with an atomic force microscope（共著）
I. Umezu, Takashi Yoshida, K. Matsumoto, A. Sugimura and M. Inada
Appl. Phys. Lett. 81, 1492 - 1493 2002.11
Joint Work
Authorship：Lead author
-
Preparation of SiNx film by pulsed laser ablation in nitrogen gas ambient（共著）
I. Umezu, T. Yamaguchi, K. Kohno, M. Inada and A. Sugimura
Appl. Surf. Sci. 197-198C, 314 - 316 2002.11
Joint Work
Authorship：Lead author
-
Effects of annealing on luminescence properties of si nanocrystallites prepared by pulsed laser ablation in inert gas（共著）
I. Umezu, G. Yamazaki, T. Yamaguchi, A. Sugimura, T. Makino, Y. Yamada, N. Suzuki and T. Yoshida，
Materials Science & Engineering C Vol 15/1-2, (2001)129-131， 2001.11
Joint Work
Authorship：Lead author
-
Many body effect in photo-conductivity in InAs/GaAs self assembled quantum dots（共著）
M. Inada, K. Ohnishi, I. Umezu, P. O. Vaccaro and A. Sugimura
Mat. Res. Soc. Symp. Proc. 642, (2001)J3.3.2-J3.3.6 2001.11
Joint Work
-
Effects of inter-dot electronic coupling on laser gain in InAs/GaAs quantum dot ensemble（共著）
A. Sugimura, K. Ohnishi, I. Tadamasa and I. Umezu
Mat.Res.Soc.Symp.Proc., 642, (2001)J5.5.1-J5.5.6， 2001.11
Joint Work
-
Conduction-type control of Ge films grown on (NH4)2S-treated GaAs by molecular beam epitaxy（共著）
M. Inada, T. Fujishima, I. Umezu, A. Sugimura and S. Yamada
Journal of Crystal Growth 227-228, (2001)791-795 2001.11
Joint Work
-
Photoluminescence from Nanoscale Si in a-SiOx matrix（共著）
I. Umezu, K. Yoshida, M. Inada and A. Sugimura，
Mat. Res. Soc Symp. Proc. 638, (2001)F5.19.1-F5.19.6 2001.11
Joint Work
Authorship：Lead author
-
Effect of Non-equilibrium Pulsed Ejection of Si Species into Background Gas on the Formation of Si Nanocrystallite and Nanocrystal-film Reviewed
Ikurou Umezu, Shunto Okubo, Akira Sugimura
Mater. Res. Soc. Symp. Proc. 1305 2001.11
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Lateral photo-conductance via in-plane interdot tunneling in self-assembled InAs/GaAs quantum dot ensemble
Ohnishi K, Inada M, Umezu I, Sugimura A, Vaccaro PO
PROCEEDINGS OF THE 25TH INTERNATIONAL CONFERENCE ON THE PHYSICS OF SEMICONDUCTORS, PTS I AND II 87 1063 - 1064 2001
Joint Work
-
Lateral photo-conductance via in-plane inter-dot tunneling in self-assembled InAs/GaAs quantum dot ensemble（共著）
K. Ohnishi, M. Inada, I. Umezu, A. Sugimura and P. O. Vaccaro
Proc.25th Int. Conf. Phys. Semicond 1063 - 1064 2000.11
Joint Work
-
correlation between Photoluminescence Intensity and Micro Structure in Amorphous Silicon Films Prepared by Reactive RF Sputtering（共著）
Umezu, T. Murota, M. Kawata, Y. Takashima, K.-i. Yoshida, M. Inada and A. Sugimura
Jpn. J. Appl. Phys. 39 Part2, (2000)L844-L846, 2000.11
Joint Work
Authorship：Lead author
-
Optical Properties of Self-assembled InAs Quantum Dots Grown on GaAs(211)A Substrates（共著）
A. Sugimura, K. Ohnishi, I. Umezu and P. O. Vaccaro
Thin film solids 380, 97 - 100 2000.11
Joint Work
-
Photoluminescence property of self-assembled InAs/GaAs quantum dots on GaAs(211)A at low coverage（共著）
K. Ohnishi, P. O. Vaccaro, K. Hara, I. Umezu and A. Sugimura
Mem. konan Univ., Sci Ser. 47(1), 21 - 29 2000.11
Joint Work
-
Structure, optical absorption and electronic states of Zn+ ion implanted and subsequently annealed sol-gel anatase TiO2 films（共著）
K. Oyoshi, N. Sumi, I. Umezu, R. Souda, A. Yamazaki, H. Haneda and T. Mitsuhashi
Nuclear Instruments and Methods in Physics Research B 168/2, 221 - 228 2000.11
Joint Work
-
Microstructure in a-SiOx prepared by RF sputtering method and its effect on radiative recombination mechanism（共著）
K. Yoshida, M. Inada, I. Umezu and A. Sugimura
Mem. konan Univ. , Sci. Ser. 47 (2) 119 - 132 2000.11
Joint Work
-
Resonance Raman Scattering of Br2 Doped Single-Walled Carbon Nanotube Bundles
梅津郁郎
Mo. Cryst. and Liq. Cryst. 340, 757 - 762 2000.11
Single Work
-
Journal of Non-Crystalline Solids 266-9（共著）
H. Kataura, Y. Kumazawa, N. Kojima, Y. Maniwa, I. Umezu, S. Masubuchi, S. Kazama, Y. Ohtsuka, S. Suzuki and Y. Achiba
Journal of Non-Crystalline Solids 266-9, 1029 - 1032 2000.11
Joint Work
-
Correlation between photoluminescence intensity and micro structure in amorphous silicon films prepared by reactive RF sputtering
Umezu I, Murota T, Kawata M, Takashima Y, Yoshida K, Inada M, Sugimura A
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS 39 ( 8B ) L844 - L846 2000.8
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A comparative study of the photoluminescence properties of a-SiOx : H film and silicon nanocrystallites
Umezu I, Yoshida K, Sugimura A, Inokuma T, Hasegawa S, Wakayama Y, Yamada Y, Yoshida T
JOURNAL OF NON-CRYSTALLINE SOLIDS 266 1029 - 1032 2000.5
-
Optical properties of single-wall carbon nanotubes
Kataura H, Kumazawa Y, Maniwa Y, Umezu I, Suzuki S, Ohtsuka Y, Achiba Y
SYNTHETIC METALS 103 ( 1-3 ) 2555 - 2558 1999.6
-
Effects of thermal processing on photoluminescence of Si nanocrystallites prepared by pulsed laser ablation
Umezu I, Shibata K, Yamaguchi S, Sato H, Sugimura A, Yamada Y, Yoshida T
PROCEEDINGS OF THE FIFTH INTERNATIONAL SYMPOSIUM ON QUANTUM CONFINEMENT: NANOSTRUCTURES 98 ( 19 ) 40 - 48 1999
Joint Work
-
Optical absorption and resonance Raman scattering of carbon nanotubes
Kataura H, Kumazawa Y, Kojima N, Maniwa Y, Umezu I, Masubuchi S, Kazama S, Zhao X, Ando Y, Ohtsuka Y, Suzuki S, Achiba Y
ELECTRONIC PROPERTIES OF NOVEL MATERIALS - SCIENCE AND TECHNOLOGY OF MOLECULAR NANOSTRUCTURES 486 328 - 332 1999
Joint Work
-
Effects of thermal processes on photoluminescence of silicon nanocrystallites prepared by pulsed laser ablation
Umezu I, Shibata K, Yamaguchi S, Sugimura A, Yamada Y, Yoshida T
JOURNAL OF APPLIED PHYSICS 84 ( 11 ) 6448 - 6450 1998.12
-
Nano-oxidation of vanadium thin films using atomic force microscopy
Vaccaro PO, Sakata S, Yamaoka S, Umezu I, Sugimura A
JOURNAL OF MATERIALS SCIENCE LETTERS 17 ( 22 ) 1941 - 1943 1998.11
-
Effect of plasma treatment on the density of defects at an amorphous Si : H-insulator interface
Umezu I, Kuwamura T, Kitamura K, Tsuchida T, Maeda K
JOURNAL OF APPLIED PHYSICS 84 ( 3 ) 1371 - 1377 1998.8
-
Defect formation mechanism during plasma enhanced chemical vapor deposition of undoped a-Si : H
Maeda K, Umezu I
JOURNAL OF NON-CRYSTALLINE SOLIDS 227 43 - 47 1998.5
-
A study of interface state density between a-Si : H and insulating layer in terms of plasma surface reaction
Umezu I, Tsuchida T, Maeda K
JOURNAL OF NON-CRYSTALLINE SOLIDS 227 1235 - 1239 1998
-
Temperature-dependent photoluminescence of silicon nanocrystallites prepared by inert-gas-ambient pulsed laser ablation
Umezu I, Yamaguchi S, Shibata K, Sugimura A, Yamada Y, Yoshida T
MATERIALS AND DEVICES FOR SILICON-BASED OPTOELECTRONICS 486 219 - 224 1998
Joint Work
-
Defect formation during deposition of undoped a-Si:H by rf glow discharge
Maeda K, Umezu I, Ishizuka H
PHYSICAL REVIEW B 55 ( 7 ) 4323 - 4331 1997.2
-
Defect formation mechanism during PECVD of a-Si : H
Maeda K, Umezu I
AMORPHOUS AND MICROCRYSTALLINE SILICON TECHNOLOGY - 1997 467 573 - 578 1997
-
Investigation of interface state density between a-Si:H and insulating layers by ESR and photothermal deflection spectroscopy
Umezu I, Kitamura K, Maeda K
JOURNAL OF NON-CRYSTALLINE SOLIDS 198 778 - 781 1996.5
-
Optical properties of silicon nanocrystallites prepared by excimer laser ablation in inert gas
Yamada Y, Orii T, Umezu I, Takeyama S, Yoshida T
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 35 ( 2B ) 1361 - 1365 1996.2
-
Defect formation during deposition of undoped a-Si:H by PECVD
Maeda K, Umezu I
AMORPHOUS SILICON TECHNOLOGY - 1996 420 569 - 574 1996
-
Optical properties of silicon nanocrystallites prepared by pulsed laser ablation in inert gas ambient
Yoshida T, Yamada Y, Takeyama S, Orii T, Umezu I, Makita Y
LASER PROCESSING OF MATERIALS AND INDUSTRIAL APPLICATIONS 2888 6 - 13 1996
-
A COMPARATIVE-STUDY ON STRUCTURAL AND ELECTRONIC-PROPERTIES OF PECVD A-SIOX WITH A-SINX
MAEDA K, SAKAMOTO N, UMEZU I
JOURNAL OF NON-CRYSTALLINE SOLIDS 187 287 - 290 1995.7
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MECHANISM OF SURFACE-REACTION IN THE DEPOSITION PROCESS OF ALPHA-SI-H BY RF GLOW-DISCHARGE
MAEDA K, KUROE A, UMEZU I
PHYSICAL REVIEW B 51 ( 16 ) 10635 - 10645 1995.4
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OPTICAL-BOND GAP AND TAUC GAP IN A-SIOX-H AND A-SINX-H FILMS
UMEZU I, MIYAMOTO K, SAKAMOTO N, MAEDA K
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 34 ( 4A ) 1753 - 1758 1995.4
-
ANALYSIS OF JOULE HEAT IN A-SI-H FILM BY PHOTOTHERMAL DETECTION SPECTROSCOPY
UMEZU, I, K MAEDA
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 33 ( 10 ) 5647 - 5651 1994.10
Joint Work
Publisher：JAPAN J APPLIED PHYSICS
Photothermal deflection (PD) signals without applied bias are a direct observation of nonradiative recombination processes of photoexcited carriers, which strongly correlate with photocurrent under applied bias. The PD signal under DC bias was carefully compared with the photocurrent (PC) signal in the energy region around and above the band gap. A large dip, which was not observed in PC spectra, was observed in PD spectra in the spectral region near the absorption edge. This spectral feature was discussed from the standpoint of Joule heat due to drift of photocarriers. We have pointed out that dark Joule heat (W-d) and effective applied voltage (V-s) are important in analysis. By taking into account these parameters, the experimental spectrum of PD signals under DC bias was successfully reproduced. It is concluded that variation of V-s which arises from large photosensitivity causes a dip in PD spectra. No evidence of the photon energy dependence of the recombination process was observed in PD spectra.
-
DEPLETION LAYER WIDTH IN UNDOPED A-SI-H SCHOTTKY-BARRIER REVEALED BY REVERSE BIAS PHOTOCURRENT
K MAEDA, W CHIYODA, UMEZU, I, A KUROE
JOURNAL OF APPLIED PHYSICS 75 ( 7 ) 3522 - 3529 1994.4
Joint Work
Publisher：AMER INST PHYSICS
Reverse bias photocurrent of undoped a-Si:H Schottky barrier was investigated under excitation with uniformly absorbed light. Dependence of the photocurrent on the applied voltage V gives unambiguous dependence of the depletion layer width W on voltage V, which cannot be obtained by conventional capacitance-voltage measurements for undoped a-Si:H. There are two voltage ranges giving parabolic dependence of W with different apparent ionized donor densities due to a spatial variation of the space-charge density. These observations are considered to be characteristic of semiconductors with major deep gap states of large energy width. The experimental results were analyzed using a simple model of energy distribution of the gap state density of dividing the depletion layer into two. In one of these deep depletion occurs. The variation of the apparent W-V relation observed upon lowering the exciting photon energy was analyzed to be related to a decrease in the absorption coefficient with the applied voltage due to an emptying of the initial states of the gap state absorption. Results of the analysis are consistent with the electron-spin density observed in the same undoped a-Si:H.
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Analysis of joule heat in a-Si:H film by photothermal deflection spectroscopy
Ikurou Umezu, Keiji Maeda
Japanese Journal of Applied Physics 33 ( 10R ) 564 - 561 1994
Joint Work
Photothermal deflection (PD) signals without applied bias are a direct observation of nonradiative recombination processes of photoexcited carriers, which strongly correlate with photocurrent under applied bias. The PD signal under DC bias was carefully compared with the photocurrent (PC) signal in the energy region around and above the band gap. A large dip, which was not observed in PC spectra, was observed in PD spectra in the spectral region near the absorption edge. This spectral feature was discussed from the standpoint of Joule heat due to drift of photocarriers. We have pointed out that dark Joule heat (W d) and effective applied voltage (V S) are important in analysis. By taking into account these parameters, the experimental spectrum of PD signals under DC bias was successfully reproduced. It is concluded that variation of V S which arises from large photosensitivity causes a dip in PD spectra. No evidence of the photon energy dependence of the recombination process was observed in PD spectra. © 1994 IOP Publishing Ltd.
DOI： 10.1143/JJAP.33.5647
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INTERFACE STATE DENSITY OF SINX-H/C-SI MIS STRUCTURE
MAEDA K, JINNAI T, UMEZU I
JOURNAL OF NON-CRYSTALLINE SOLIDS 166 849 - 852 1993.12
Joint Work
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ATOMIC MICROSTRUCTURE AND ELECTRONIC-PROPERTIES OF A-SINX-H DEPOSITED BY PECVD
MAEDA K, UMEZU I
JOURNAL OF NON-CRYSTALLINE SOLIDS 137 883 - 886 1991.12
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INVESTIGATION OF SINX-H/SI INTERFACE BY CAPACITANCE METHOD
K MAEDA, UMEZU, I, A KAWAGUCHI
APPLIED PHYSICS LETTERS 59 ( 19 ) 2421 - 2423 1991.11
Joint Work
Publisher：AMER INST PHYSICS
A new capacitance method was developed to investigate properties of the SiN(x):H/c-Si interface. By comparison of the frequency dependence of C-V characteristics of p- and n-type c-Si substrate sample pairs, flatband voltage for an intrinsic substrate sample can be determined. Analyses of two kinds of frequency dependence, i.e., the variation of voltage at flatband capacitance and the variation of capacitance at flatband voltage, disclose different aspects of the interface state density with respect to the energy level in the band gap, response time, and ionized state. Donor states are predominant in the investigated interface.
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STRUCTURE OF AMORPHOUS SINX-H STUDIED BY PHOTOEMISSION AND INFRARED-ABSORPTION
UMEZU, I, K MAEDA
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 30 ( 10 ) 2547 - 2552 1991.10
Joint Work
Publisher：JAPAN J APPLIED PHYSICS
We present an X-ray photoemission (XPS) and infrared absorption (IR) study of hydrogenated amorphous silicon-nitride (SiNx:H) films which were prepared by plasma decomposition of SiH4 and NH3. Both Si 2p (XPS) and Si-H (IR) peaks are decomposed to contributions from Si-centered tetrahedrons. The peak shift in both XPS and IR can be divided into two compositional regions: below and above x = 1.0. Peak energy increases gradually with x until it reaches 1.0. For x > 1.0, the increment of peak shift is small. There are no particular features at around stoichiometric composition, x = 1.33. The kink point at around x = 1.0 and maximum composition of x = 1.7 are discussed in terms of Si-centered tetrahedrons. The Si-Si bond, which decreased with increasing source gas ratio R (R = [NH3]/[SiH4]), did not disappear even though a large gas ratio R was given. This feature is important in accounting for the structure of the films.
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ATOMIC MICROSTRUCTURE AND ELECTRONIC-PROPERTIES OF A-SINX-H DEPOSITED BY RADIO-FREQUENCY GLOW-DISCHARGE
K MAEDA, UMEZU, I
JOURNAL OF APPLIED PHYSICS 70 ( 5 ) 2745 - 2754 1991.9
Joint Work
Publisher：AMER INST PHYSICS
a-SiN(x):H films of various composition x were deposited by rf glow discharge (GD). The deposition rate was analyzed for three ranges of gas flow ratio R = [NH3]/[SiH-4] depending on the deposition mechanism. Properties of these films were measured by means of x-ray photoelectron spectroscopy (XPS), infrared (IR) absorption, optical absorption, and the temperature dependence of electrical conductivity. The composition x was determined by XPS. For large values of R, x was found to be saturated at 1.7. The variation of H content was detected by IR absorption. The variation of coordinating atoms of Si with increasing x was deduced from the variation of XPS spectra of the Si 2p core-level and the shift of Si-H stretching vibration frequency in IR absorption. Based on the random bonding model and assuming bonding units to the central Si atom to be Si, N, and NH, probabilities of Si tetrahedra with various coordinating units were obtained. The results indicate that there are many Si-Si bonds for the stoichiometric x = 1.33 and that the concentration of Si-Si bonds diminishes at around the saturation value x = 1.7. These results seem to imply that the presence of Si-Si bonds to some extent is a prerequisite condition for film deposition by GD. Experimental results of optical absorption analyzed by Tauc relation revealed the presence of two kinds of x region whose properties are quite different. For x < 1.5, its optical absorption is similar to a-Si:H modified by the presence of N. With increasing x, the optical band gap E(O) increases and B coefficient in the Tauc plot decreases. At about x = 1.5, Si-Si bonding effectively disappears and the optical absorption abruptly changes to that similar to beta-Si3N4. Considering these results, the change of electronic band structure with x was deduced on the basis of the atomic structure obtained above and by the tight binding approximation. For x < 1.5, the optical band gap is due to Si-Si bonding, the energy gap of which increases, and the linear band tail becomes broad with increasing x. From the observed temperature dependence of conductivity, variations of the activation energy and pre-exponential factor are obtained with x up to x = 1.0. For the decrease of conductivity with x, the contribution from the pre-exponential factor is much larger than that from the activation energy. This result can be understood by a transport mechanism in the electronic band structure obtained above. Finally, it is concluded that the electronic properties of a-SiN(x):H deposited by GD ranging from semiconductor to insulator can be explained by the atomic microstructure and the electronic energy band structure.
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NONIDEAL J-V CHARACTERISTICS AND INTERFACE STATES OF AN A-SI-H SCHOTTKY-BARRIER
K MAEDA, UMEZU, I, T YOSHIMURA, H IKOMA
JOURNAL OF APPLIED PHYSICS 68 ( 6 ) 2858 - 2867 1990.9
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光音響法による非輻射遷移過程の研究
梅津郁朗
1990.3
Single Work
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A comparative study of photoluminescence properties of a-SiOx:H film and silicon nanocrystallites（共著）
I. Umezu, K. Yoshida, A. Sugimura, T. Inokuma, S. Hasegawa, Y. Wakayama, Y. Yamada and T. Yoshida
- 1111.11
Joint Work
Authorship：Lead author
A comparative study of photoluminescence properties of a-SiOx:H film and silicon nanocrystallites