静压下ZnS：Te中Te等电子陷阱的发光

研究了4块ZnS：Te薄膜样品(Te组分从0．5％到3．1％)的光致发光谱在常压下的温度特性．对于Te组分较小的2块样品观察到2个发光峰，分别来自Te1和Te2等电子陷阱；而对Te组分较大的2块样品则只观察到1个来自Te2等电子陷阱的发光．我们还研究了这些发光峰在低温1．5K下的流体静压压力行为．观察到与Te1有关的发光峰压力系数比ZnS带边的要大很多，而与Te2有关的发光峰压力系数则比带边小．根据Koster-Slater模型，价带态密度半宽随压力的增加是Te1中心有较大压力系数的主要原因，而Te1和Te2中心的不同压力行为则是由于压力对两者缺陷势增强的不同效果引起的．

PHOTOLUMINESCENCE OF Te ISOELECTRONIC CENTERS IN ZnS:Te UNDER HYDROSTATIC PRESSURE

The photoluminescence of four epitaxial ZnS∶Te samples with Te concentration from 0.5% to 3.1% was investigated at different temperature and ambient pressure. Two well-known emission bands related to the isolated Te 1 and Te 2 pair isoelectronic centers were observed for the samples with Te concentrations of 0.5% and 0.65%. For the samples with Te concentrations of 1.4% and 3.1%, only was the Te 2-related peak observed. The pressure behaviors of these emission bands were studied at 15K. The Te 1-related band has faster pressure shift to higher energy than ZnS band gap. On the other hand, the pressure coefficient of Te 2-related bands is smaller than that of the ZnS band gap. According to a Koster-Slater model, we found that the increase of the density bandwidth of the valence band with pressure is the main reason for the faster shift of the Te 1 centers, while the relatively large difference in the pressure behavior of the Te 1 and Te 2 centers is mainly due to the difference in the pressure-induced enhancement of the impurity potential on Te1 and Te2 centers.