| 摘要: | 本論文的主題為應用在磷化銦鎵/砷化銦鎵/鍺三接面太陽能電池上的磷化銦鎵上層子電池的製備以及在一個太陽光，AM1.5G下之特性改善。 本論文的第一部分探討射極層厚度對元件特性的影響，經由實驗發現，採用較薄的射極層可增加短路電流密度，進而提升太陽能電池的轉換效率。 第二部分探討基極層摻雜方式對元件特性的影響，採用漸變的摻雜方式可在基極層內形成「漂移電場」，加強多數及少數載子的傳輸，使得太陽能電池的短路電流密度以及轉換效率得以提升。 第三部分延續第二部分的結果，在基極層採用漸變摻雜方式的基礎上，進一步增加基極層的厚度，經由實驗發現，較厚的基極層可增加短路電流密度，進而提升太陽能電池的轉換效率。 最後，三種不同的材料，亦即磷化鋁銦鎵、磷化銦鎵以及磷化鋁銦，分別被應用於製作背表面電場層。實驗結果顯示太陽能電池的表現似乎與基極層及背表面電場層接面上的傳導帶偏移量直接相關。採用磷化鋁銦當做背表面電場層材料的太陽能電池具有最大的傳導帶偏移量，因此展現出最高的短路電流密度及轉換效率。In this thesis, the GaInP solar-cells which are the top cell of the GaInP/GaInAs/Ge triple-junction solar-cell have been fabricated with several different epitaxial conditions, in order to improve the characteristics of the GaInP solar-cells under one sun, AM1.5G, condition. Firstly, the effects of emitter thickness have been studied. By employing a thinner emitter, the cell efficiency can be improved mainly due to the increasing of short-circuit current density. Secondly, different base doping profiles have been employed. The results indicate a graded base doping can generate a “drift-field” in the base region, which enhances the transports of majority and minority carriers, thus improves the short-circuit current density and conversion efficiency. Thirdly, following the consequence of the second experiment, the short-circuit current density and conversion efficiency can be further improved by employing a thicker base layer. Finally, three different materials for back-surface field (BSF) layer, AlGaInP, GaInP, and AlInP have been adopted, respectively. From the experiment results, it seems that the solar-cell performance is directly related to the degree of conduction-band offset at the interface between base and BSF. The solar-cell with an AlInP BSF which has the largest conduction-band offset, demonstrates the highest conversion efficiency, mainly due to the largest short-circuit current density. |
