静压下ZnS∶Te中Te等电子陷阱的发光

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

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 15K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

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 15 K. 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 Te-1 and Te-2 centers.