矽晶P-N介面太陽能電池特性及鍺薄膜MIS太陽能電池元件製程

Abstract

本論文中，報告了對目前市場中普遍的矽晶P-N介面太陽能電池所作的分析結果。其中二極體的理想因子(Ideality Factor)，發現比1高出許多，且接近2，表示目前矽晶太陽能電池所採用的矽基板其純度與品質與IC產業比起來是較差的。太陽能電池的溫度響應，不論是理論推導或實驗，皆顯示開路電壓為主要的變化因子。且開路電壓的變化趨勢隨溫度上升而下降，導致發電效率下降。太陽能矽基板的方向，則利用XRD作了偵測，指出其為(100)的矽基板。在如何提昇矽晶P-N介面太陽能電池效率方面，應變技術被採用於太陽能電池上。施加的應變包含單軸向與雙軸向，結果顯示應變有機會藉由提昇太陽能電池的填充因子(Fill Factor)而提昇整體發電效率。目前的實驗結果指出，電池破片在雙軸向的拉伸應變中其光電轉換效率可以有最大輻度的提昇。薄膜太陽能電池方面，採用鍺作為反應層，因為鍺具有較高的載子遷移率，且吸收深度較矽來的淺。一種低溫的薄膜轉移技術將被介紹，可以將一層1.3微米的結晶鍺薄膜轉移至鍍有ITO(Indium Tim oxide)透明導電極之玻璃上。最後以此種基板，製作出薄膜太陽能電池。

In this these, some analyses of the commercial crystalline silicon-based P-N junction solar cells are reported. The ideality factor of the solar cell is found to be much larger than 1 and close to 2. It indicates the purity and quality of silicon wafers used for the solar cells are worse than the wafers used in IC industry. For the temperature effect of solar cells, both theoretical derivation and experiment results have been carried out. It is found that open-circuit voltage reduction is the dominant factor that leading to efficiency degradation at higher temperature. And the silicon substrate of the single crystalline solar cell, is found in (100) orientation by X-ray diffraction.Besides, strain technique is used on these commercial cells, including uniaxial and biaxial strain. The results show the fill factor is enhanced by the strain technique, and the efficiency improves due to the larger fill factor. The small-piece cells with biaxial strain are found with better improvement.About the thin film solar cells. Germanium is taken as the active layer due to the higher mobility and larger absorption coefficient as compared to silicon. A low temperature wafer bonding technique is introduced. This technique is taken to transfer a 1.3μm thin film crystalline germanium on a glass with indium tin oxide coated. Then, the thin film solar cells are fabricated with this substrate.