分子束磊晶成長氯摻雜覆蓋層對硒化鎘量子點之光學特性影響

Abstract

利用分子束磊晶成長不同大小的硒化鎘量子點樣品，探討在硒化鋅覆蓋層上摻雜氯對量子點的光性影響。發現有摻雜氯之覆蓋層會影響量子點光激螢光譜峰值紅移及半高寬增加，相對於未摻雜之樣品，發光強度也明顯提升。在變溫的光激螢光光譜中，有摻雜氯覆蓋層之量子點發光強度明顯不受溫度升高而衰減，接著以阿瑞尼士方程式做擬合，可得到在高溫區中，氯摻雜覆蓋層之樣品的活化能較大。最後以變溫變功率圖的走勢可得知，硒化鎘量子點因熱所導致的熱淬減現象可因覆蓋層摻雜氯而被抑制，使其發光效率大幅提升，有助於應用在發光二極體和雷射二極體中。

CdSe quantum dots of different sizes were grown by molecular beam epitaxy. The effect of Cl-doped ZnSe capping layer on the optical properties of QDs were investigated. The existence of the Cl-doped capping layer results in a clear peak energy red-shift but also the broadening of the full width at half maximum in the photoluminescence (PL) spectrum. In addition, the emission intensity was remarkably increased. The temperature dependent PL showed that the emission intensity of the QDs capped by Cl-doped ZnSe deos not strongly depend on temperature. Following the fitting with Arrhenius equation, QDs with Cl-doped ZnSe had larger thermal activation energy in the high temperature range. The excitation power dependent PL also showed that the nonradiative recombination process was suppressed in the QDs with Cl-doped ZnSe. Current study illustrates that the CdSe QDs with Cl-doped ZnSe capping layer could improve the emission efficiency for the application in the QD light-emitting diodes and QD lasers.