論文 - 鈴木 秀俊
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Nitrogen incorporation in GaAsN grown by chemical beam epitaxy
Ohshita Y., Nishimura K., Lee H., Kojima N., Gono I., Suzuki H., Yamaguchi M.
Proceedings - Electrochemical Society PV 2005-04 272 - 277 2005年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Proceedings - Electrochemical Society
Chemical beam epitaxial growth system has been developed for achieving good quality InGaAsN thin film, which will be adopted as a third material of four-junction tandem solar cell. Methylhydrazine, which was used as a N source, was decomposed on the growing surface. Between 400-420°C, N concentration had slight temperature dependence. The adsorbed N-related molecules hindered the decomposition of Ga precursor TEG on the surface, resulting in the decrease of the growth. Above 440°C, the number of N incorporated in the grown film swiftly decreased. The growth rate had slight temperature dependence and the quality of grown film became deteriorated although the amount of residual N decreased.
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C60/a-C superlattice structures for solar cell applications
Kojima N., Terayama T., Suzuki H., Imaizumi T., Yamaguchi M.
Conference Record of the IEEE Photovoltaic Specialists Conference 118 - 120 2005年11月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Conference Record of the IEEE Photovoltaic Specialists Conference
C 60 / amorphous carbon (a-C) superlattice structures were fabricated by shutter controlled molecular beam deposition. A-C layers were transformed from C 60 by nitrogen ion bombardment. The dark and photo conductivity of C 60 /a-C superlattice structures were measured by gap-cell structure. The resulted films show high resistivity, and the photosensitivity ratio is ranged 9-16. It is thought that such low photosensitivity is caused by high defect density of 2.7×10 21 cm -3 in the a-C layers. Use of hydrogen plasma in C 60 amorphization process, instead of nitrogen, reduces the spin defect density in two orders of magnitude. Hydrogen atoms effectively reduce the defect density of a-C films by etching the weak carbon bond structures and/or passivating the dangling bonds. © 2005 IEEE.
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Nishimura K., Lee H., Suzuki H., Gono I., Kojima N., Ohshita Y., Yamaguchi M.
Conference Record of the IEEE Photovoltaic Specialists Conference 722 - 724 2005年11月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Conference Record of the IEEE Photovoltaic Specialists Conference
GaInNAs films for the ultra high-efficiency ( > 40%) 4-junction tandem space solar cells ((Al)GaInP/GaAs/ GaInNAs/Ge) have been grown by using chemical beam epitaxy (CBE) in this study. In the growth of GaInNAs films, the selection of nitrogen source and understanding of nitrogen incorporation is important because nitrogen is play an important role in the crystallization and electrical properties of III-V-N compound materials. A proper nitrogen source between monomethylhydrazine (MMHy) and dimethylhydrazine (DMHy) was investigated, and the nitrogen incorporation in samples grown with MMHy was higher. From the dependence of nitrogen concentration on the substrate temperature, three distinct regions were observed, even in the nitrogen concentration usually decreased with increasing the substrate temperature, and a low FWHM value was obtained at an intermediate temperature. In addition, the dependence of the nitrogen incorporation on the ratio of N/(N+As) was investigated, and at a low temperature, the nitrogen concentration increased with increasing the ratio of N/(N+As). From these results, the nitrogen incorporation in GaInNAs films grown with the substrate temperature and the ratio of N/V elements in CBE technique is clarified, and the relationships between the nitrogen incorporation and crystallization of GaInNAs are clear. ©2005 IEEE.
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Structure of the Si(1 1 3) surface studied by surface X-ray diffraction
Mizuno Y., Akimoto K., Aoyama T., Suzuki H., Nakahara H., Ichimiya A., Sumitani K., Takahashi T., Zhang X., Sugiyama H., Kawata H.
Applied Surface Science 237 ( 1-4 ) 40 - 44 2004年10月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Applied Surface Science
We carried out a grazing incidence X-ray diffraction analysis of the Si(113) 3 × 1 surface using synchrotron radiation. We compared the experimental structure factors obtained from the integrated intensities of the fractional-order reflections with the calculated structure factors of the dimerized structure model of Ranke. By minimizing the R-factor, we determined the position and the size of the pentagon in the 3 × 1 dimerized structure model of Ranke. In addition, we found that a model with randomly distributed interstitial atoms at the center of the pentagon gi ves a smaller R-factor value. © 2004 Elsevier B.V. All rights reserved.
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Ga-induced nano-facet formation on Si(1 1 n) surfaces
Nakahara H., Suzuki H., Miyata S., Ichimiya A.
Applied Surface Science 212-213 ( SPEC. ) 334 - 338 2003年5月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Applied Surface Science
Surface morphology of three kinds of Si(1 1 n) surfaces during Ga deposition has been studied by scanning tunneling microscopy to investigate nano-facet formation processes on high-index silicon surfaces. It has been observed that Si(1 1 3) surfaces with vicinal angles of ±2° changed into nano-facet structures of (1 1 2) and (1 1 5) at 1 ML Ga deposition as well as a flat Si(1 1 3). In contrast, no faceting occurred on Si(1 1 4). In all cases of nano-facet formation, (1 1 2) facet formed prior to (1 1 5) facet. Thus, it is considered that (1 1 2) facet formation is a driving force of nano-facet formation process. It is also considered that large angle difference between (1 1 2) and (1 1 4) prevents the facet formation on Si(1 1 4). Difference of vicinal direction appears in distribution of facet width. The facet width distribution strongly depends on the initial morphology on the surface tilted toward [3 3 2̄] direction, while on the surface tilted toward [3 ̄ 3̄ 2] , initial morphology does not affect the final facet distribution. © 2003 Elsevier Science B.V. All rights reserved.
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Surface morphology of Ga adsorbed Si(1 1 3) surface
Suzuki H., Nakahara H., Miyata S., Ichimiya A.
Surface Science 493 ( 1-3 ) 166 - 172 2001年11月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Surface Science
Surface morphology and reconstruction of Ga adsorbed Si(1 1 3) surface have been investigated using scanning tunneling microscopy and reflection high-energy electron diffraction. Surface reconstruction changes from clean 3 × 2 structure to 3 × 1 structure at 0.2 ML Ga deposition. Then the surface changes to 2 × 2 structure at 0.4 ML Ga deposition. For more than 1 ML Ga deposition, well-ordered one-dimensional facet structure is formed with its width of about 5 nm. The two faces of the facet are determined as (1 1 2) and (1 1 5) surfaces. The surfaces have N × 1 (N=4-8) and 4 × 1 reconstructions, respectively. On (1 1 2) facet, mostly observed structure is 6 × 1, and this result agrees with previously reported result of Ga deposition on flat (1 1 2) surface. While on (1 1 5) surface, two kinds of 4 × 1 structures which are symmetric to [332̄] direction are observed. It is considered that nucleation of (1 1 2) facet leads a flat (1 1 3) surface to facet structure. © 2001 Elsevier Science B.V. All rights reserved.