Papers - UMEZU Ikurou
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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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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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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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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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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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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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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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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.