AgGa(S_(1-x)Se_x)_2固溶体的电子结构和光学性质

Electronic Structures and Optical Properties of AgGa(S_(1-x)Se_x )_2 Solid Solutions

采用基于赝势平面波基组的密度泛函理论方法,对一系列具有黄铜矿结构的AgGa(S1-xSex)2固溶体的构型、电子结构、线性和二阶非线性光学性质进行了系统研究.结果表明,各固溶体具有类似的能带结构,体系带隙随x值增加而逐渐减小.当所引入的Hartree-Fock交换项贡献为22.56%时,对应的杂化PBE泛函得到的带隙值与实验结果相近.固溶体的各种光学性质,包括折射率、双折射率、反射率、吸收系数和二阶倍频系数等均随着组成的改变呈现出有规律的变化趋势,变化范围介于AgGaS2和AgGaSe2二者之间.因此,利用固溶体光学性质的变化规律,可从中寻找出具有特定光学性能的晶体材料.

Density functional theory （DFT） based on the plane wave basis set was used to investigate the geometries, electronic structures, and linear and second-order nonlinear optical properties of a series of AgGa（S~_xSex）2 solid solutions with chalcopyrite structures. The compounds showed similar band structures, and band gaps decreased with increasing x value. When 22.56% Hartree-Fock exchange was employed, the solid solution band gaps predicted by hybrid PBE functionals were consistent with experimental values. The optical properties of AgGa（S1-xSex）2 solid solutions, including refractive index, birefringence, reflectivity, adsorption coefficient, and second harmonic generation coefficient, changed regularly with composition. The range of variation was between that for AgGaS2 and AgGaSe2. The results indicated that crystals with specialized optical performances could be designed.