成果報告書詳細
管理番号20090000000286
タイトル*平成20年度中間年報 新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)ポストシリコン超高効率太陽電池の研究開発(集光型多接合)
公開日2009/8/21
報告書年度2008 - 2008
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技術開発部 太陽電池グループ
和文要約以下本編抜粋:1. 研究開発の内容及び成果等 サブテーマ1: 4接合太陽電池の研究開発 本サブテーマでは、新規な1eV 材料としてケミカル・ビーム・エピタキシー(CBE)法を用いた高品質なInGaAsN 材料を開発することにより、AlInGaP/GaAs/InGaAsN/InGaAs(2.0eV/1.4eV/1.0eV/0.67eV)、AlInGaP/GaAs/InGaAsN/Ge の4 接合セルの研究開発を行う。
英文要約Title:R & D on Innovative Solar Cells (International Research Center for Innovative Solar Cell Program) “Research and Development of Post-silicon solar cells for ultra-high efficiencies (Concentrator Multi-Junction Solar Cells)” (FY2008-FY2010) FY2008 Annual Report 1. Development of 4-juction cells with InGaAsN new materials: (1) High-quality InGaAsN growth by Chemical Beam Epitaxy (CBE): The CBE-grown (In)GaAsN crystal quality depends on the atomic step density and step directions on the growing surface. We investigated the surface step effects on the GaAsN growth by using vicinal GaAs (001) substrates. The step structure is defined as A-, B-, and AB-step for the three different step directions. By increasing AB-step density, we achieved the reduction of the carrier scattering centers of the N-rich GaAsN films.: (2) Crystal growth simulation for III-V-N materials: The relationships between solid composition of InGaN thin films and MOVPE growth conditions were investigated. We carried out thermodynamic analyses and empirical interatomic potential calculations to clarify the influence of lattice constraint from bottom layer on In incorporation ratio into the films. The results well reproduce the composition pulling effect. This approach is applicable to other system such as InGaAsN.: (3) Electrical characterization and defect study: The temperature dependence of hole mobility was analyzed by parameter fitting. The unknown scattering center density increased linearly with increasing N composition. This result suggests that the origin of unknown scattering is point defect contained one N atom. Minority carrier traps in p-type GaAsN were investigated by using deep level transient spectroscopy (DLTS). We have confirmed experimentally the existence of recombination center in p-type GaAsN.: (4) Development of single junction solar cells: We developed Si-doped n-type GaAsN films grown by CBE using silane as doping source. The carrier concentration of n-type GaAsN could be controlled by the silane flow rate and the growth temperature. We tested the single homo-junction cells consisted of the Si-doped n-type GaAsN and undoped p-type GaAsN.: 2. Analysis of materials and cells under concentrator operation: (1) Analysis of misfit dislocations and their reduction: In situ real-time x-ray diffraction measurements during the InGaAs/GaAs epitaxy were performed first time to understand the strain relaxation mechanisms in the lattice-mismatched system. The obtained results allow us to evaluate the evolution of the residual strain and crystal quality simultaneously as a function of the layer thickness. The regions with different strain relaxation mechanisms are classified, and the dominant dislocation motions such as dislocation generations, multiplications or interactions could be deduced in each region.: (2) Development of simulator for analysis of concentrator photovoltaic modules: By connecting the ray trace simulation and circuit simulation with multi-unit model, we analyzed the I-V characteristics of concentrator photovoltaic modules, totally. The developed simulator enables the total optimization of concentrator photovoltaic modules.
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