硒化物半导体纳米材料光学吸收谱的温度特征

目的研究半导体纳米薄膜材料的光学吸收谱由于温度效应产生的吸收边变化和能带移动。方法采用共沉淀法制备了硒化物半导体纳米薄膜材料CdSe,并测量材料在室温至低温下的紫外-可见吸收光谱,观察不同温度下谱带吸收边的变化。结果实验发现光学吸收边随温度降低而发生蓝移的情况,将(αhν)2～hν曲线直线部分外推,与横轴的截距即为材料带隙宽度Eg,数据模拟结果显示Eg随温度变化是非线性的,且能带随温度的变化较好地符合Fernandez公式。结论进而分析造成吸收谱温度效应的原因是温度变化对晶格参数及电子-声子相互作用的影响,引起能带边缘的相对移动,导致吸收边能量位置的漂移,并从理论公式上表达了带隙变化随温度的依赖关系。

The temperature characteristic of optical absorption spectra for nanostructured selenide semiconductors

Aim To investigate the changes of absorption edge and band shift of the optical absorption spectra of the semiconductor nanometer films which are caused by temperature effects.Methods Selenide semiconductor CdSe nanometer films was prepared with co-precipitation method,then the changes of absorption edge at different temperatures via UV-Vis absorption spectra from room temperature to low temperature were observed.Results It was found experimentally that blue shift occurred on the optical absorption edge as temperature went down,the intercept between the extrapolated straight part of curve(αhν) 2~hν,and the transverse axis was the band gap Eg,the data simulation results show that Eg with temperature was nonlinear and accorded well with the Fernandez formula.Conclusion Based on the analysis of temperature effects of absorption spectra,temperature effects had an influence on the lattice parameter and electron-phonon interaction,causing relative movement of the band edge and absorption edge shift,the temperature dependence of the band gap Eg was derived by theoretical formula.