成果報告書詳細
管理番号20110000000645
タイトル*平成22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)高度秩序構造を有する薄膜多接合太陽電池の研究開発(ナロー/ワイドギャップ、高性能透明導電膜、有機単結晶)
公開日2011/8/25
報告書年度2010 - 2010
委託先名国立大学法人東京工業大学
プロジェクト番号P07015
部署名新エネルギー部
和文要約和文要約等以下本編抜粋:1. 研究開発の内容及び成果等
半那純一担当分
【1】 Si 基板上でのGe ヘテロエピタキシャル成長技術の検討と太陽電池の試作
前年度までの検討により、Si2H6-GeF4を原料ガスとすGe(100)基板へホモエピタキシャル成長条件を確立できた。この条件(350ºC、2torr、Si2H6:GeF4=7.5:1sccm/sccm)をもとに基板をSi(100)基板に変えてヘテロエピタキシャル成長を検討したところ、エピタキシャル成長は認められるものの、格子定数のミスマッチに起因する結晶性の劣化や表面モルフォロジーの劣化のみならず、Ge組成の低下が認められた。そこで、成長初期における成長条件、特に、本CVD法に特有な成長支配因子である基板温度、ガスの滞留時間、膜の表面成長モードに注意しながら、再度、成膜条件ついて検討した。その結果、GeF4の表面吸着により膜成長が支配されると思われる基板温度300oC以下の条件では、図1のRHEED、AFMによる表面モフォロジーに示すようにから判断されるように、結晶性、表面モルフォロジーが改善し、Ge組成が98%以上まで向上が見られた。
英文要約Title: Exploring multi-junction thin-film solar cells with highly ordered structures (FY2008-2010) FY2009 Annual Report
-Development of epitaxial growth of single crystalline germanium and its related materials
Epi-Ge thin films were fabricated on Si(100)) substrates by the reactive thermal CVD with Si2H6-GeF4 at the optimized condition for homoepitaxial growth of Ge established previously, but crystallinity and surface morphology of the films were degraded due to the lattice mismatch with the Si substrate. In order to improve the crsytallinity of the films, the growth condition was reexamined in the surface growth mode at temperature region below 350oC. The film crystallinety was improved much when the film was deposited at 275oC, but the deposition rate was too low to apply cell fabrication. According to these results, new condition was established to satisfy both a reasonable growth rate of a few A/s and high crystallinity: the epi-Ge fims were deposited at a rate 2-4 A/s at 350oC and 0.7 to 2 torr.
-Development of novel wide gap oxide semiconductors for solar cells
In order to clarify the possibility of a-IGZO as an n-type layer of solar cells, p-type Si/n-type a-IGZO solar cells were fabricated: the efficiency, JSC, VOC, and FF of the optimized solar cell were 5.3%, 28 mA/cm2, 0.31 V and 0.61, respectively. The C–V and XPS measurements revealed that the prime cause of low VOC was the deep CBM of a-IGZO: An oxide with shallow CBM is preferable for realizing solar cells with high VOC.
-Development of high-performance transparent conducting thin film technology using wonder-glass substrates
In this work, we examined the crystal growth and electric properties of ITO (indium tin oxide) thin films on our originally developed nanoimprinted-glass substrates in order to fabricate the high-performance TCO (transparent conducting oxide) thin films for the thin film solar cell.
-Development of a new solar cell device based on single crystalline organic semiconductors
We have made a great progress in the development of the flux-mediated organic epitaxy with ILs; the principle of this new process has been verified. In the following FY2011, we will try to fabricate an organic solar cell device and demonstrate its benefit from using the organic single crystal in view of energy conversion efficiency.
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