氧硒化鋅/砷化鎵太陽能電池

中間能帶材料在太陽能電池的應用中是目前相當具有潛力的概念，主要原因在於中間能隙帶能有效延伸光譜的吸收範圍。在本論文中，我們首次以中間能帶材料，氧硒化鋅 (ZnSeO)，應用於太陽能電池的結構中，並以理論及實驗檢視氧硒化鋅太陽能電池的特性。文中首先探討不同氧含量之氧硒化鋅的結構與光學特性，其中大於10^4 cm-1的吸收係數使得氧硒化鋅在太陽能電池上的應用具有相當程度的潛力。本文中亦引用一中間能帶太陽能電池理論計算，同時將氧硒化鋅材料的各項參數導入，其結果顯示具中間能隙的氧硒化鋅太陽能電池光電轉換效率可達25 % 。為實現該太陽能電池，文中以p型砷化鎵為基板，於上成長氧硒化鋅和n型氧化鋅以形成一p-n二極體。為減少太陽能電池的串聯電阻及電流傳輸上的功耗，文中提出鈦/鋁/鎳/金 (Ti/Al/Ni/Au)歐姆接觸，且在高摻雜鎵摻雜氧化鋅薄膜上可達到相當低的特徵接觸阻值為2.6×10^-7 Ω-cm2。元件特性顯示，相較於硒化鋅吸收層的太陽能電池，氧硒化鋅太陽能電池增加了16 %的短路電流，且開路電壓維持不變，轉換效率可提高約43 %。但由於材料品質的問題及尚在開發階段的磊晶技術，因此本實驗中未能實際觀察到中間能帶的現象，但也為接續的材料開發與應用踏出重要的一步。

關鍵字

硒化鋅；中間能帶；太陽能電池；氧硒化鋅

並列摘要

To date, materials with intermediate band become potential applications in solar cells because the spectral response could be extended by the intermediate band in the forbidden gap. In this thesis, we first demonstrated the ZnSeO based intermediate band solar cells and its characteristics were particularly investigated. The structural and optical properties of ZnSeO with varying oxygen content were studied in this work. The high absorption coefficients (>104 cm-1) of ZnSeO made it a promising candidate in solar cell. Theoretical calculation based on self-consistent drift-diffusion method was referred in this work. The results showed the conversion efficiency of ZnSeO based solar cell could reach 25 %. To realize the solar cell structure, ZnSeO with n-ZnO window layer were grown on p-GaAs substrate in this study. We also propose Ti/Al/Ni/Au ohmic contact to minimize the series resistance and power consume in solar cells, and low specific contact resistivity of 2.6×10-7 Ω-cm2 could be achieved. The ZnSeO based solar cells exhibit a 16 % increase of the short circuit current and same open circuit voltage in comparison to ZnSe based cells. Thus, a 43 % improvement in conversion efficiency could be obtained. However, existence of intermediate band could not be observed in ZnSeO solar cell because of the quality issues. This work does provide the opportunities for ZnSeO applied in photovoltaic devices.

並列關鍵字

ZnSe ； ZnSeO ； solar cells ； intermediate band

參考文獻

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國際替代計量

氧硒化鋅/砷化鎵太陽能電池

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