气相外延ZnSe单晶膜的自由激子发光

本文在77K和N2激光器3371谱线高密度激发的VPE ZnSe单晶膜上,首次得到了起因于自由激子与自由激子(Ex-Ex)散射的发光谱带(P带),理论拟合了该谱带的形状并讨论了它的发光特性。文中把在选择的VPE ZnSe外延单晶膜中得到P带的起因归结为这些ZnSe外延单晶膜的质量较高。

FREE EXCITON EMISSION IN VPE ZnSe EPILAYERS

In recent years, the research on Ⅱ-Ⅵ compound semiconductors such as ZnSe and CdS has special attention. The most interesting work is to study the free exciton emission in the Ⅱ-Ⅵ crystals under high excitation density1]. Saito et al2]. observed E and P bands in ZnSe in photoluminescence (PL) within 4.2-65K,which they attributed to exciton-electron(Ex-e)and exciton-exciton (Ex-Ex) interaction, respectively. Colak et al3]. reported the stimulated emission in ZnSe crystal excited by electron beam. L. Ma et al. observed the P band excited by N2 Laser in VPE ZnSe epilayer at 64K. Up to now, there has been no report on Ex-Ex interaction in VPE ZnSe epilayer under high excitation density at 77K.In this work,a new band PA Was found at the low energy side of EA band under high excitation density. The origin of the new PA band was investigated.The ZnSe epilayer used in this work was grown on (100) GaAs substrate with VPE method. The ZnSe epilayer was excited by N2 Laser with the pulse width of 10ns, repetition frequency of 10Hz and the maximal pulse density of 2MW/cm2. PL spectra were measured using a grating spectrograph of model 44W with C31034 cooled photomultiplier.Fig.1 and Fig.2 show the PL spectra of the selected (specimen A) and ordinary (specimen B) ZnSe single crystal epilayers under different excitation . densities at 77K.