Manufacturing technology (mechanical, electrical/electronic, chemical engineering), Measurement engineering

Natural sciences, Magnetism, superconductivity, and strongly correlated systems

1969
Tohoku University, 工学研究科, 電子工学専攻, Japan

1969
Tohoku University, Graduate School, Division of Engineering

1966
Tohoku University, 工学研究科, 電気及び通信工学専攻, Japan

1966
Tohoku University, Graduate School, Division of Engineering

1964
The University of Electro-Communications, Faculty of Electro-Communications, 電波通信学科, Japan

1964
The University of Electro-Communications, Faculty of Electro Communications

266 nm pulsed laser-induced oxygen atoms desorbed from 873 K high temperature,high vacuum pretreated rutile TiO₂
2000, Surf. Sci., 445, 480-487

Preparation and evaluation of nitrogen-terminated silicon nanoparticles: laser annealing effect
CK Choo; T Sakamoto; M Tohara; K Tanaka; R Nakata; N Okuyama
Nitrogen-terminated silicon nanoparticles were synthesized on AFI AlPO4-5 zeolite by pulsed laser ablation of silicon target in the presence of 1.33 x 10(-5) Pa of ammonia and were annealed by multiple laser shots at 532 nm. The samples were characterized by X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy and UV-vis absorption measurements. The results indicate that they are composed of nonstoichiometric silicon nitride nanoparticles as well as silicon species with dangling bonds. NHx (x = 1,2) polyhydride species are dissociated by pulsed laser annealing, which shows the improvement of the silicon and silicon nitride crystallinities. It is suggested that the nanoparticles will agglomerate as clusters after laser annealing. According to the Tauc plot obtained from UV-vis absorption data, a blue shift of band gap energy from bulk silicon was observed. (C) 2000 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV, Jan. 2000, SURFACE SCIENCE, 445, 2-3, 480-487, English, 0039-6028, WOS:000085085500035

266 nm pulsed laser-induced oxygen atoms desorbed from 873 K high temperature,high vacuum pretreated rutile TiO₂
2000, Surf. Sci., 445, 480-487

Preparation and evaluation of nitrogen-terminated silicon nanoparticles: laser annealing effect
CK Choo; T Sakamoto; M Tohara; K Tanaka; R Nakata; N Okuyama
Nitrogen-terminated silicon nanoparticles were synthesized on AFI AlPO4-5 zeolite by pulsed laser ablation of silicon target in the presence of 1.33 x 10(-5) Pa of ammonia and were annealed by multiple laser shots at 532 nm. The samples were characterized by X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy and UV-vis absorption measurements. The results indicate that they are composed of nonstoichiometric silicon nitride nanoparticles as well as silicon species with dangling bonds. NHx (x = 1,2) polyhydride species are dissociated by pulsed laser annealing, which shows the improvement of the silicon and silicon nitride crystallinities. It is suggested that the nanoparticles will agglomerate as clusters after laser annealing. According to the Tauc plot obtained from UV-vis absorption data, a blue shift of band gap energy from bulk silicon was observed. (C) 2000 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV, Jan. 2000, SURFACE SCIENCE, 445, 2-3, 480-487, English, 0039-6028, WOS:000085085500035

"蛍石型バルク混晶 Ca_1-xSr_xF₂ のX線結晶性評価"
Mar. 1999, 日本物理学会、講演概要集2, 95

Analysis of space charge relaxation by equivalent electric circuit for yttrium doped CaF(2)
K Tanaka; K Tanaka; K Kawano; R Nakata
Characteristic behaviours of high temperature ionic thermocurrent (HT ITC) in CaF(2):Y were studied by a usual ITC method with Teflon insulated electrodes in the nominal yttrium concentration range from n = 0.002 to 30 mol%. An equivalent electric circuit was used to analyze HT ITC by assuming a space charge how model with a specific resistivity in the form of rho(T) = rho(sysc) T exp(E(a)/kT). The analysis revealed that a relaxation of the space charges occurred in the specific resistivity from insulating to semi-insulating change-over of CaF(2):Y crystal. In addition, dependences of the peak temperature shift and total charge of HT ITC on the crystal thickness could be explained by taking into account the capacitance of the crystal. And the yttrium concentration dependence of the activation energy for the space charge flow could be well approximated by E(a)(n) = E(ao) = gamma n(1/3). (C) 1998 Elsevier Science Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD, Feb. 1999, JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS, 60, 2, 247-256, English, 0022-3697, 80010852872, WOS:000078135500013

Analysis of space charge relaxation by equivalent electric circuit for yttrium doped CaF(2)
K Tanaka; K Tanaka; K Kawano; R Nakata
Characteristic behaviours of high temperature ionic thermocurrent (HT ITC) in CaF(2):Y were studied by a usual ITC method with Teflon insulated electrodes in the nominal yttrium concentration range from n = 0.002 to 30 mol%. An equivalent electric circuit was used to analyze HT ITC by assuming a space charge how model with a specific resistivity in the form of rho(T) = rho(sysc) T exp(E(a)/kT). The analysis revealed that a relaxation of the space charges occurred in the specific resistivity from insulating to semi-insulating change-over of CaF(2):Y crystal. In addition, dependences of the peak temperature shift and total charge of HT ITC on the crystal thickness could be explained by taking into account the capacitance of the crystal. And the yttrium concentration dependence of the activation energy for the space charge flow could be well approximated by E(a)(n) = E(ao) = gamma n(1/3). (C) 1998 Elsevier Science Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD, Feb. 1999, JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS, 60, 2, 247-256, English, 0022-3697, 80010852872, WOS:000078135500013

X-Ray Excitation Fluorescence of the Eu²⁺-stabilized VK Center in Alkaline Earth Fluoride Mixed-Crystal Systems
KAWANO K; OHYA T; TSURUMI T; KATOH K; NAKATA R
1999, Phys. Rev. B, 60, 17, 11984-11992, 0163-1829, 80010763276

Oxygen containing silicon clusters on teflon and their work functions studied with x-ray photoelectron spectroscopy and Ultraviolet Photoelectron spectroscopy
TANAKA K; SAKAMOTO T; TOHARA M; CHOO C‐K; NAKATA R
1999, App. Surf. Sci., 148, 3/4, 215-222, 0169-4332, 80011189679

Characterization of nitrogen terminated silicon nanoparticles on AFI zeolite with x-ray and ultraviolet photoelectron spectroscopies
CHOO C‐K; SAKAMOTO T; TANAKA K; NAKATA R
1999, App. Surf. Sci., 148, 1/2, 116-125, 0169-4332, 80011155065

Negatively charged subnanometer-sized silicon clusters and their reversible migration into AFI deolite studied with x-ray photoelectron spectroscopy and ultraviolet lectron spectroscopy
CHOO C‐K; SAKAMOTO T; TANAKA K; NAKATA R; ASAKAWA T
1999, Appl. Surf. Sci., 140, 1/2, 126-137, 0169-4332, 80010929388

大学力を創る，FDハンドブック（分担執筆）
1999, 東信堂

X-Ray Excitation Fluorescence of the Eu²⁺-stabilized VK Center in Alkaline Earth Fluoride Mixed-Crystal Systems
1999, Phys. Rev. B, 60, 17, 11984-11992, 0163-1829, 80010763276

Oxygen containing silicon clusters on Teflon and their work functions studied with X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy
Katsumi Tanaka; Takashi Sakamoto; Makoto Tohara; Cheow-Keong Choo; Rhouhei Nakata
Silicon species were deposited on tetrafluoroethylene (Teflon) with pulsed laser silicon ablation at 532 nm under UHV. Surface species with studied with X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). Tetrafluorocarbon (CF4) was easily desorbed by the decomposition reaction of Teflon with flying silicon species. Surface species were characterized as a function of pulsed laser shots. Silicon species were terminated with oxygen in gas phase to form two kinds of SiOx clusters (x <
0.3) in addition to oxygen terminated silicon networks. Their work functions could be estimated by the shift of their Fermi energies., Elsevier Science Publishers B.V., 1999, Applied Surface Science, 148, 3, 215-222, English, 0169-4332, 80011189679, 0032632940

Characterization of nitrogen terminated silicon nanoparticles on AFI zeolite with X-ray and ultraviolet photoelectron spectroscopies
Cheow-Keong Choo; Takashi Sakamoto; Katsumi Tanaka; Ryouhei Nakata
Nitrogen terminated silicon nanoparticles were synthesized on AFI AlPO4-5 zeolite by pulsed laser ablation of silicon target in the presence of 1.33×10-5 Pa of ammonia, and were characterized in situ by X-ray photoemission spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). Nonstoichiometric silicon nitride and unterminated silicon nanoparticles with size of estimated to be approximately 5.4 angstroms in diameter were existed. They were found to migrate and diffuse into the AlPO4-5 channels at 373 K and migrate back to the external surface at 503 K. The effect of sample annealing was studied at 373 K. The change of silicon surface state (unterminated silicon nanoparticles) to hydride species was observed concurrently with breaking of the NHx species. This result implies that the NHx species remained on the silicon particles form Si3N4 like bonds and the dissociated H-species are bound to the unterminated silicon surface., Elsevier Science Publishers B.V., 1999, Applied Surface Science, 148, 1, 116-125, English, 0169-4332, 80011155065, 0032665587

Negatively charged subnanometer-sized silicon clusters and their reversible migration into AFI deolite studied with x-ray photoelectron spectroscopy and ultraviolet lectron spectroscopy
1999, Appl. Surf. Sci., 140, 1/2, 126-137, 0169-4332, 80010929388

アンモニアを用いた窒素終端Si微粒子の作製と評価
Mar. 1998, 第45回応用物理学関連連合講演会, 29aH-2

"単結晶中の希土類イオンの発光を利用した太陽電池の高効率化"
1998

Conversion Efficiency of Solar Cell whith Ion-Implanted Rare Earth into Anti-Refilection Film
1998, Proceedings of the International 2nd World Conference of Photovoltaic Solar Energy Conversion, Vienna, Austria, 334-337

Conversion Efficiency of Solar Cell whith Ion-Implanted Rare Earth into Anti-Refilection Film
1998, Proceedings of the International 2nd World Conference of Photovoltaic Solar Energy Conversion, Vienna, Austria, 334-337