碲硒化鋅磊晶層中的碲等電性中心之光激螢光時間解析光譜

Abstract

我們使用光激螢光譜和時間解析光譜來分析參雜不同碲濃度的碲硒化鋅磊晶層(碲莫耳濃度小於百分之四十二)。我們發現不同碲濃度的碲硒化鋅複合時間在數個奈秒到數十個奈秒之間。當碲莫耳濃度由零增加到百分之十時，最長的複合時間到達七十八奈秒。複合時間的增加是由於局部位能隨碲濃度增加而變大。當碲濃度再度增加，複合時間卻隨著碲濃度的增加而減少。這現象可以被碲的局部態和主要的價帶混成的模型解釋。藉著不同碲濃度之激子束縛能、光激螢光譜的半高寬和熱活化能的結果都支持這驅勢。

ZnSe1-xTex (x ≦ 0.42) epilayers grown by molecular beam epitaxy were studied by photoluminescence (PL) and time-resolved photoluminescence (TRPL). The recombination time varies with Te concentration from a few nanoseconds to tens of nanosecond. The recombination time reaches a maximum value of about 78 ns when x increases from 0 to 0.10. The increase of the recombination time is attributed to the increasing localization potential with Te concentration. As the Te composition is further increased, the exciton recombination lifetime decreases with x. This behavior can be explained by the hybridization of Te localized states and the host valence band states. This tendency can be further supported by the dependence of the PL line width, exciton binding energy, and thermal activation energy on the Te concentration.