成果報告書詳細
管理番号20150000000013
タイトル*平成25年度中間年報 太陽エネルギー技術研究開発 革新的太陽光発電技術研究開発 (革新型太陽電池国際研究拠点整備事業) 高効率集光型太陽電池セル、モジュール及びシステムの開発 (日EU 共同開発) 新材料・新構造太陽電池の創製及び評価解析技術の開発(WP1)
公開日2015/5/1
報告書年度2013 - 2013
委託先名豊田工業大学
プロジェクト番号P07015
部署名新エネルギー部
和文要約
英文要約Title:R & D on Innovative Solar Cells (International Research Center for Innovative Solar Cell Program) "Ultra-high efficiency concentration photovoltaic’s (CPV) cells, modules and systems (WP 1:New materials and device characterization)" (FY2011-FY2014) FY2013 Annual Report

1. III-V-N novel materials: N-H bonds found in GaAsN grown by chemical beam epitaxy have [1-10] orientations. They have different degrees of the orientations: N-H bonds with vibration frequencies of 960, 2952, and 3098 cm-1 have infrared absorption intensity ratios of [1-10]- to [110]-polarization of 2:1, 5:1, and 6:4, and N-H bond with the frequency of 3011 cm-1 is almost completely oriented to [1-10]. The different orientation degrees indicate that those N-H bonds belong to different kinds of N-H complexes. Therefore, there are at least four kinds of N-H complexes.: Growth temperature dependent recombination kinetics of photo-generated charge carriers and the changes of N-H species in GaAsN were studied by time-resolved IR absorption spectroscopy. We found that the lifetime of photo-generated charge carriers becomes longer by increasing the growth temperature from 633 K to 693 K. The absorption intensity and the vibrational frequency of N-H species in GaAsN were also changed by the band gap photo-excitation, and these changes were also affected by the growth temperature. The changes of the N-H species are responsible to the capture of photo-generated charge carriers therefore it was indicated that the N-H species are responsible to the change of the lifetime of photo-generated charge carriers.: 2. III-V on Si structure: The dislocation defects in GaP/Si sample provided from Fraunhofer ISE were investigated. The cross-sectional TEM observations were intended to find some dislocations. However, there were no threading dislocations in the observed areas. Then, we applied an X-ray topography method to estimate the density of threading dislocation. Analysis is under way.: The effects of pre-evaporation of group III atoms onto Si(111) surface on the formation of rotational twin have been analyzed. It was observed that the Ga pre-evaporation enhanced the formation of rotational twin domains (TW), while the In pre-evaporation effectively reduced the formation of TW at low V/III ratio. The pre-evaporation of In and Ga resulted in the formation of InAs and GaAs 3D islands, respectively. The analyses on the surface morphologies after pre-evaporation revealed that the In pre-evaporation resulted in smaller 3D islands, while Ga pre- evaporation led to larger islands. These results suggested that the size of island formed during the initial pre-evaporation phase ultimately controlled the TW growth in the final GaAs film.: A GaAsSb buffer layer for the epitaxial growth of GaAs on Si substrate was investigated. Significant reduction of dislocation density at the interface between the GaAs layer and the buffer layer was confirmed by TEM. This thin buffer layer that reduces dislocations has a potential to improve GaAs crystal quality and facilitate the fabrication of high-quality multi-junction solar cells on Si substrates.
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