低維度二六族半導體之成長與光電性質之研究

Abstract

低維度半導體已廣泛地被應用在光電半導體產業，並在學術研究上引起很大的注意。在此論文中，我們將會呈現在三種不同的二六族半導體奈米結構系統其特有的光電性質。在一維CdSe奈米結構成長方面，我們發現經由改變MOCVD系統中的磊晶參數，可在一次的製程中同時生長出不同形狀、不同晶體結構的一維CdSe。在矽太陽能電池的研究中，利用乾蝕刻所製作的錐狀表面提供了極佳的抗反射效果；將CdSe或CdTe的量子點灑在已做好的電池上，發現其功率可分別提升約兩成與四成，而這樣的結果歸因於量子點在光吸收與電子（或電洞）傳輸上皆有所助益。在ZnTe/ZnSe的研究中，我們發現在ZnSe中加入少量Te（δ-doped Te）或者成長ZnTe量子點，會分別形成等電子中心與type-II 的能帶結構，所觀察到的螢光光譜和時間解析螢光光譜皆有很大的差異。

Low-dimensional semiconductors systems have attracted much attention recently because they have many interesting properties and can have many potential technological applications. In this thesis we present our studies on the optical and electrical properties of three different II-VI semiconductor nanostructure systems. In the growth of one-dimensional CdSe nanostructures, different shapes and crystalline structures of one-dimensional CdSe were fabricated in a single process successfully by changing the growth parameters with a MOCVD system. In the study of Si solar cell, the efficiency of the solar cells was enhanced about 20 % or 40 % by spraying CdSe or CdTe quantum dots on the surfaces of textured Si wafer. The enhancement was attributed to the contribution of quantum dots in photo absorption and electron (or hole) transport. In the study on ZnTe/ZnSe system, the results demonstrate that there are two different mechanisms responsible for the green PL emission in ZnSeTe system and our growth methods provide a way of selecting one of the two mechanisms for the green light emission in this system.