| Project/Area Number |
23360163
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | Waseda University |
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Principal Investigator |
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| Co-Investigator(Renkei-kenkyūsha) |
KAWAHARAZUKA Atsushi 早稲田大学, 理工学術院, 准教授 (40329082)
FUJITA Miki 早稲田大学, 理工学術院, 次席研究員 (60386729)
NISHINAGA Jiro 早稲田大学, 理工学術院, 准教授 (90454058)
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| Project Period (FY) |
2011-04-01 – 2015-03-31
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| Project Status |
Completed (Fiscal Year 2014)
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| Budget Amount *help |
¥19,890,000 (Direct Cost: ¥15,300,000、Indirect Cost: ¥4,590,000)
Fiscal Year 2014: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2013: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2012: ¥7,670,000 (Direct Cost: ¥5,900,000、Indirect Cost: ¥1,770,000)
Fiscal Year 2011: ¥9,880,000 (Direct Cost: ¥7,600,000、Indirect Cost: ¥2,280,000)
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| Keywords | 太陽電池 / 温度安定性 / 励起子吸収効果 / 分子線エピタキシー / 超格子太陽電池 / AlGaAs/GaAs超格子 / Si/SiO2超格子 / スパッタリング / 超格子 / タンデム太陽電池 / 励起子吸収 / AlGaAs/GaAs / 解放電圧 / Si/SiO2 / 半導体 / 薄膜・量子構造 / 作成・評価技術 / 表面 / 界面 / エピタキシャル成長 / 結晶評価 / ヘテロ構造 |
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| Outline of Final Research Achievements |
One of the most serious problems of solar cells is the degradation of solar cell efficiency(η) at elevated temperatures. This effect is probably caused by the bandgap(Eg) shrinkage at elevated temperatures. The shrinkage of Eg decreases Voc, and as a result, lowers η.In semiconductor superlattices(SLs), effective Eg includes an increment by quantum confinement effect which is rather temperature insensitive. Therefore, temperature stable solar cells could be achieved by using SL absorption layers.
We have fabricated AlGaAs/GaAs SL solar cells by using an optimized SL structure grown by MBE. Both Voc andη are found to be more temperature-stable compared with GaAs bulk solar cells with an equivalent solar cell structure. Even at 100℃, dη/dT is as low as 0.22%/deg which is the lowest ever reported. In addition, in SL solar cells, the excitonic absorption is found to be operative even at elevated temperatures which lead to the higher efficiency compared to bulk solar cells.
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