CdS单晶中的绿色电致发光和光致发光

在50-290K温度范围内,研究了在正向电压激发下,用高纯CdS单晶制备的MIS发光二极管的电致发光光谱。在室温时,发射光谱分别由峰值为5135±25Å和5300±15Å的二个绿色谱带所组成,而在低温下,观测到有很多结构的光谱。在50K时,自由和束缚激子的发射实际上占有统治地位。文中提出,在室温时,谱峰为5135±25Å的谱带是与受导带自由电子散射的自由激子的发射有关;而谱峰为5300±15Å的谱带归结为与同时发射二个纵光学声子的自由激子的发射有关。比较了刚生长的高阻CdS单晶以及在熔融镉中热处理的低阻CdS单晶的光致发光光谱。在熔融镉中的热处理抑制了自由到束缚(HES)和束缚到束缚(LES)的边缘发射,也抑制了I2束缚激子谱线,但是增强了自由激子的发射,在电场激发下,也使自由激子的发射增强。

GREEN ELECTROLUMINESCENCE AND PHOTOLUMINESCENCE IN CdS

The electroluminescence emission spectrum of forward-biased MIS diodes on high-purity single crystal CdS has been studied over the temperature range 50-290K.At room temperature the emission consisted of two intense bands in the green at 5135±25Å and 5300±15Å,while at lower temperatures considerably more structure was observed.Thus at 50K free and bound ex-citon emission was particularly prominent. Evidence is presented to suggest that the band at 5135±25A at room temperature is associated with free ex-citon recombination following scattering from free electrons in the conduction band.The band at 5300±15A is attributed to free exciton recombination with the emission of two longitudinal optical phonons.The photoluminescence emission of as-grown CdS crystals has been compared with that of crystals rendered semiconducting by heat treatment in molten cadmium.This treatment suppressed the free-to-bound(HES) and bound-to-bound edge emission.As well as the I1 bound exciton line,which was also preferentially excited ion electroluminescence.