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Son, N. T.*; Hemmingsson, C. G.*; Paskova, T.*; Evans, K. R.*; Usui, Akira*; Morishita, Norio; Oshima, Takeshi; Isoya, Junichi*; Monemar, B.*; Janz
n, E.*
Physical Review B, 80(15), p.153202_1 - 153202_4, 2009/10
Times Cited Count：40 Percentile：79.94(Materials Science, Multidisciplinary)GaN samples were irradiated with electrons of 2 MeV at 1
10
/cm
, and electron spin resonance (ESR) was measured at 77 K. As a result, four defect signals which are labeled D1 to D4 were observed. The D2 signal was identified to be negatively charged gallium vacancy - oxygen pair from the details studies of 
N hf structure.
Ishii, Yasuyuki; Isoya, Akira*; Kojima, Takuji; Arakawa, Kazuo
Nuclear Instruments and Methods in Physics Research B, 211(3), p.415 - 424, 2003/11
Times Cited Count：17 Percentile：72.74(Instruments & Instrumentation)A beam width measurement system has been developed for keV submicron ion beams of 0.1 
m or less in width assuming a round shape beam. The system enables to measure beam current change as a function of knife-edge position by cutting a beam focusing point (beam spot) with the sharp edge within a spatial resolution of 0.02 m. The width of 30 keV order submicron 
ion beam was estimated by fitting current change curves based on three different ion density models: uniform, flat-top and Gaussian. Among these models, the flat-top model provide the most reasonable beam width of 0.56 m interpreting contribution of halo around the beam spot to beam width estimation. The beam width measurement system with the high spatial resolution and the data analysis based on the flat-top ion density model should contribute to accelerate developments of submicron ion beam production technologies.
Ishii, Yasuyuki; Isoya, Akira*; Kojima, Takuji
Nuclear Instruments and Methods in Physics Research B, 210, p.70 - 74, 2003/09
Times Cited Count：13 Percentile：64.66(Instruments & Instrumentation)The conception for this microbeam formation, which consists in combining beam contraction effect of acceleration process with the lens action, was published in 1991. The test machine was installed in JAERI. The study of reducing beam size showed that the incident beam condition strongly depend on its size. Recently about 40 keV stable microbeam 
of 0.1 m order in radius has been obtained after optimizing the ion beam injection system. The test machine is composed of a duoplasmatron-type discharge source, an initial acceleration system, a main acceleration lens system, and microbeam diameter measurement system. We will present the schematic of the test machine and the result of the beam size measurement. Performance of the system will also show to depend mostly on how nicely a low energy injection beam is prepared at the entrance region.
Ishii, Yasuyuki; Isoya, Akira*; Arakawa, Kazuo; Kojima, Takuji; Tanaka, Ryuichi*
Nuclear Instruments and Methods in Physics Research B, 181(1-4), p.71 - 77, 2001/07
Times Cited Count：14 Percentile：68.97(Instruments & Instrumentation)no abstracts in English
Ishii, Yasuyuki; Isoya, Akira*; Arakawa, Kazuo; Tanaka, Ryuichi*
JAERI-Conf 2000-019, p.117 - 120, 2001/02
no abstracts in English
Ishii, Yasuyuki; Isoya, Akira*; Tanaka, Ryuichi
F-113-'98/NIES, p.105 - 108, 1998/00
no abstracts in English
Ishii, Yasuyuki; Tanaka, Ryuichi; Isoya, Akira*
Nuclear Instruments and Methods in Physics Research B, 113(1-4), p.75 - 77, 1996/06
Times Cited Count：16 Percentile：77.77(Instruments & Instrumentation)no abstracts in English
Ishii, Yasuyuki; Isoya, Akira*; Tanaka, Ryuichi
Dai-8-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.74 - 77, 1996/05
no abstracts in English
Komatsubara, Akira*; Teraji, Tokuyuki*; Hori, Masahiro*; Kumagai, Kuninori*; Tamura, Shuto*; Oshima, Takeshi; Onoda, Shinobu; Yamamoto, Takashi; Muller, C.*; Naydenov, B.*; et al.
no journal, ,
no abstracts in English
Tamura, Shuto*; Komatsubara, Akira*; Teraji, Tokuyuki*; Onoda, Shinobu; Oshima, Takeshi; Christoph, M.*; Naydenov, B.*; McGuinness, L.*; Jelezko, F.*; Shinada, Takahiro*; et al.
no journal, ,
no abstracts in English
Tamura, Shuto*; Komatsubara, Akira*; Teraji, Tokuyuki*; Onoda, Shinobu; McGuinness, L.*; Jelezko, F.*; Rogers, L.*; Oshima, Takeshi; Isoya, Junichi*; Shinada, Takahiro*; et al.
no journal, ,
no abstracts in English
