Pb_(1-x)Sr_xSe薄膜材料的微结构和光学特性

Microstructure and Optical Properties of Pb_(1-x)Sr_xSe Thin Films

采用分子束外延的方法在BaF_2衬底(111)上制备出了高质量的Pb_(1-x)Sr_xSe(0≤x≤0.050)薄膜.X射线衍射结果表明,Pb_(1-x)Sr_xSe薄膜为立方相NaCl型晶体结构,没有观察到SrSe相分离现象,薄膜的取向为平行于衬底(111)晶面.薄膜晶格常数随Sr含量的增加逐渐增大,Sr含量由Vegard公式得到.再用理论模拟Pb_(1-x)Sr_xSe薄膜透射光谱的方法得到了相应的带隙.最后通过介电函数模型拟合得到了PbSe和Pb_(1-x)Sr_xSe薄膜在光子能量位于基本带隙附近的折射率n和吸收系数α.

High quality Pb1-xSrxSe （0≤ x ≤0.050） thin films were grown on BaF：（111） substrates by using molecular beam epitaxy（MBE）. Optical and structural properties of the Pb1-xSrxSe films were studied using transmission spectrum and high resolution X-ray diffraction （HRXRD）. HRXRD patterns indicate that Pb1-xSrxSe films has cubic-phase structure, with no SrSe phase separation. The films orientation is parallel to （111） surface of substrate. The lattice constants of the Pb1-xSrxSe films increase with increasing Sr content. The Sr content can be obtained by using Vegard formula. Sharp absorption edges are observed in the transmission spectrum of Pb1-xSrxSe films. The fundamental band gap of the Pb1-xSrxSe films is attained by simulation. Refractive indexes and absorption coefficients near the fundamental band-gap are obtained by simulation using dielectric function model（DFM）.