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4); Comparison of X-ray diffraction and first-principles calculationTakahashi, Masamitsu; Kratzer, P.*; Penev, E.*; Mizuki, Junichiro
Surface Science, 600(18), p.4099 - 4102, 2006/09
Times Cited Count：1 Percentile：6.63(Chemistry, Physical)The GaAs(001)-c(44) has been studied by synchrotron surface X-ray diffraction. The atomic coordinates and Debye-Waller factors were determined up to the sixth layer from the surface. The results support the formation of the Ga-As heterodimers. The resultant atomic coordinates were compared with those given by a first-principle calculation. In spite of the theoretical prediction of the stability of the single-heterodimer structure, our data fit best a three-heterodimer model where three heterodimers are present in one unit cell. The preference of the formation of the three heterodimers will be discussed in the relationship with the transition process from the 24 to the c(44) structures.
Nishitani, Tomohiro; Nakanishi, Tsutomu*; Yamamoto, Masahiro*; Okumi, Shoji*; Furuta, Fumio*; Miyamoto, Masaharu*; Kuwahara, Makoto*; Yamamoto, Naoto*; Naniwa, Kenichi*; Watanabe, Osamu*; et al.
Journal of Applied Physics, 97(9), p.094907_1 - 094907_6, 2005/05
Times Cited Count：64 Percentile：87.28(Physics, Applied)no abstracts in English
Imaizumi, Mitsuru*; Sumita, Taishi*; Kawakita, Shiro*; Oshima, Takeshi; Ito, Hisayoshi; Kuwajima, Saburo*
Proceedings of 31st IEEE Photovoltaic Specialists Conference and Exhibition (PVSC-31), p.563 - 566, 2005/00
no abstracts in English
Ekins-Daukes, N. J.*; Arafune, Koji*; Lee, H. S.*; Sasaki, Takuo*; Yamaguchi, Masafumi*; Khan, A.*; Takamoto, Tatsuya*; Agui, Takaaki*; Kamimura, Kunio*; Kaneiwa, Minoru*; et al.
Proceedings of 31st IEEE Photovoltaic Specialists Conference and Exhibition (PVSC-31), p.683 - 686, 2005/00
no abstracts in English
4 surfaces under molecular-beam epitaxy conditionsTakahashi, Masamitsu; Yoneda, Yasuhiro; Mizuki, Junichiro
Applied Surface Science, 237(1-4), p.219 - 223, 2004/10
Times Cited Count：5 Percentile：29.73(Chemistry, Physical)The GaAs(001)-
reconstructed surface was investigated by in situ surface X-ray diffraction. The sample was subjected to measurements under molecular-beam epitaxy conditions without being transferred another chamber. Several X-ray diffraction patterns were measured with increasing the substrate temperature within the 
-phase of GaAs(001)- in a constant As flux of 510
Torr. At relatively low temperatures up to 545
C, the observed X-ray diffraction patterns agree well to the 2(24) surface. However, a different X-ray diffraction pattern was obtained at 585C, while the 
periodicity still persited. This change is explained by partial As-dimer desorption which results in a mixture of the 2(24) and 
2(24) structures.
Chandrasekaran, N.*; Soga, Tetsuo*; Inuzuka, Yosuke*; Taguchi, Hironori*; Imaizumi, Mitsuru*; Oshima, Takeshi; Jimbo, Takashi*
Japanese Journal of Applied Physics, 43(10A), p.L1302 - L1304, 2004/10
Times Cited Count：6 Percentile：27.8(Physics, Applied)no abstracts in English
Hirao, Toshio; Laird, J. S.; Onoda, Shinobu; Wakasa, Takeshi; Ito, Hisayoshi
Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-6), p.187 - 189, 2004/10
no abstracts in English
Oyama, Hidenori*; Takakura, Kenichiro*; Nakabayashi, Masakazu*; Hirao, Toshio; Onoda, Shinobu; Kamiya, Tomihiro; Simoen, E.*; Claeys, C.*; Kuboyama, Satoshi*; Oka, Katsumi*; et al.
Nuclear Instruments and Methods in Physics Research B, 219-220, p.718 - 721, 2004/06
Times Cited Count：3 Percentile：24.88(Instruments & Instrumentation)no abstracts in English
Imaizumi, Mitsuru*; Takamoto, Tatsuya*; Sumita, Taishi*; Oshima, Takeshi; Yamaguchi, Masafumi*; Matsuda, Sumio*; Oi, Akihiko; Kamiya, Tomihiro
Proceedings of 3rd World Conference on Photovoltaic Energy Conversion (WCPEC-3) (CD-ROM), 4 Pages, 2004/01
The radiation response of InGaP, InGaAs and Ge single junction sub-cells in the triple junction space solar cell are studied in order to develop a device simulator which predicts the End-Of-Life performance of space solar cells. InGaP top-cells show no significant difference in radiation response between under AM0 light and dark conditions during irradiation. The radiation resistance of InGaAs cell which is used as middle cell decreases with increasing In contents. The Ge cell shows lower radiation reisitance as compared to InGaP and InGaAs cells.
4 surfaceTakahashi, Masamitsu; Yoneda, Yasuhiro; Yamamoto, Naomasa*; Mizuki, Junichiro
Physical Review B, 68(8), p.085321_1 - 085321_5, 2003/08
Times Cited Count：17 Percentile：62.72(Materials Science, Multidisciplinary)The , and 
phases of the GaAs(001)-24 surface have been investigated by 
surface X-ray diffraction in an As flux and at temperatures ranging from 480C to 610C. It has been found that the fractional-order peaks originating from the fourfold symmetry show shift in the [110] direction as well as significant broadening of the peaks in the and phases. The direction of the peak shift is characteristic in each phase. This behavior is explained by the formation of the antiphase domain boundaries. The atomic structure of the domain boundaries is discussed.
Sumita, Taishi*; Imaizumi, Mitsuru*; Matsuda, Sumio*; Oshima, Takeshi; Oi, Akihiko; Ito, Hisayoshi
Nuclear Instruments and Methods in Physics Research B, 206, p.448 - 451, 2003/05
Times Cited Count：55 Percentile：94.77(Instruments & Instrumentation)Proton irradiation effects of triple-junction (InGaP/GaAs/Ge) solar cells for space use were studied. The changes in electrical and optical properties of the solar cells irradiated with protons at energies between 20 keV and 10 MeV were examined. As the result of analyzing the relationship between proton projection range and the degradation of their properties, the largest degradation of the properties was observed when proton projection range is near the junction of GaAs sub-cells. This indicates that improvement of the radiation resistance of GaAs is necessary to enhance radiation resistance of tliple-junction solar cells.
Oshima, Takeshi; Imaizumi, Mitsuru*; Takamoto, Tatsuya*; Sumita, Taishi*; Oi, Akihiko; Kawakita, Shiro*; Ito, Hisayoshi; Matsuda, Sumio*
Proceedings of 5th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications, p.113 - 116, 2002/10
The effects on proton and electron irradiateions of the characteristics of InGaP/GaAs/Ge triple junction designed for terrestrial application were studied. The solar cells used in this study has a 1% In-contained GaAs middle sub-cell, and their efficiency is more than 30 % under AM1.5, which is the highest efficiency of all solar cells in the world.As the results of 1MeV-electron and 10 MeV-proton irradiation, terrestrial triple-junction sole cells were found to have the same radiation resistance as space single junction GaAs solar cells, although terrestrial triple-junction solar cells is not stronger than space triple-junction solar cells made in USA. As the result of proton energy dependence of the electrical characteristics and quantum efficiency, the strong degradation of the GaAs middle cell was observed.
Laird, J. S.; Hirao, Toshio; Onoda, Shinobu*; Mori, Hidenobu*; Ito, Hisayoshi
Proceedings of 5th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications, p.155 - 160, 2002/10
no abstracts in English
InGaP solar CellsDharmarasu, N.*; Khan, A.*; Yamaguchi, Masafumi*; Takamoto, Tatsuya*; Oshima, Takeshi; Ito, Hisayoshi; Imaizumi, Mitsuru*; Matsuda, Sumio*
Journal of Applied Physics, 91(5), p.3306 - 3311, 2002/03
Times Cited Count：25 Percentile：66.93(Physics, Applied)3MeV proton irradiation effects on InGaP single junction and InGaP/GaAs two junction cells were studied. The degradation of electrocal properties for InGaP cells was smaller than that for InGaP/GaAs cells. The results of the measurement of spectral response showed the large degradation in long wavelength. This indicates that GaAs cell degrades. The Damage coefficient of minority carrier diffusion length was estimated to be 7.910
for InGaP and 1.610
for GaAs. These values of the damage coefficient for InGaP and GaAs are 580 times and 280 times larger than those for InGaP and GaAs irradiated with 1MeV electrons.
-ray irradiationOyama, Hidenori*; Hirao, Toshio; Simoen, E.*; Claeys, C.*; Onoda, Shinobu; Takami, Yasukiyo*; Ito, Hisayoshi
Physica B; Condensed Matter, 308-310, p.1185 - 1188, 2001/12
Times Cited Count：8 Percentile：44.9(Physics, Condensed Matter)no abstracts in English
Dharmarasu, N.*; Yamaguchi, Masafumi*; Khan, A.*; Yamada, Takashi*; Tanabe, Tatsuya*; Takagishi, Shigenori*; Takamoto, Tatsuya*; Oshima, Takeshi; Ito, Hisayoshi; Imaizumi, Mitsuru*; et al.
Applied Physics Letters, 79(15), p.2399 - 2401, 2001/10
Times Cited Count：75 Percentile：90.91(Physics, Applied)The radiation response of 3MeV proton-irradiated InGaP, InGaAsP, and InGaAs solar cells was measured and analyzed in comparison with those of InP and GaAs. The degradation of the minority-carrier diffusion length was estimated from the spectral response. The damage coefficient K
for 3MeV proton-irradiated InGaP, InGaAsP and InGaAs was also determined. The radiation resistance increases with increase in the function of In-P bonds in those materials. Minority-carrier injection under forward bias is found to cause partial recovery of the degradation on irradiated InGaP and InGaAsP cells.
Hirao, Toshio; Ito, Hisayoshi; Okada, Sohei; Nashiyama, Isamu*
Radiation Physics and Chemistry, 60(4-5), p.269 - 272, 2001/03
Times Cited Count：5 Percentile：38.96(Chemistry, Physical)no abstracts in English
Yoshino, Yoko; Takarabe, Kenichi*; Ishii, Masashi*; Katayama, Yoshinori; Shimomura, Osamu
Physica B; Condensed Matter, 273-274, p.781 - 783, 1999/12
Times Cited Count：1 Percentile：8.71(Physics, Condensed Matter)DX state is strongly localized. This nature could be investigated by observing relaxation process of localized electrons to emptied inner shells. We have found two different optical ionization process of the DX center in Al
Ga
As:Se (x=0.33,
(cm
)) by using synchrotron radiation. They are tentatively assigned to be a direct lift of an inner-shell electron to the conduction band (CB) followed by a capture of an electron at the DX center to the emptied inner shell 
K-edge
and the Auger ionization of one electron of the DX center to the CB followed by a capture of another electron to the emptied inner shell K-edge
.
*; *; Matsuda, Sumio*; Oshima, Takeshi; Nashiyama, Isamu
Proceedings of 3rd International Workshop on Radiation Effects on Semiconductor Devices for Space Application, p.63 - 68, 1998/00
no abstracts in English
Kuriyama, Kazuo*; Kazama, K.*; Kato, Takashi*; Yamamoto, Shunya; Aoki, Yasushi; Naramoto, Hiroshi
Journal of Applied Physics, 80(8), p.4488 - 4490, 1996/10
Times Cited Count：1 Percentile：8.28(Physics, Applied)no abstracts in English
