Improved Electronic Structure and Optical Performance of Bi2Te3-xSex From First-principle Calculations Within TB-mBJ Exchange Potential

Using the first-principle calculations of density functional theory within the (FP-LAPW) method, we have investigated the structural, electronic and optical properties of Bi2Te3-xSex alloys with compositions x = 0, 1, 2 and 3 of Se. The generalized gradient approximation functional of Wu and Cohen (GGA-PBE) is used to calculate ground state structural parameters of Bi2Te3-xSex , which are in good agreement with theoretical and experimental data. The electronic band structures and optical constants have been improved with Tran-Blaha modified Becker-Johnson (TB-mBJ) parameterization scheme. Also, we have analyzed in detail the performance of dielectric function, refractive index, reflectivity and optical conductivity of these alloys. Our results show that Bi2Te3-xSex alloys are promising candidates for optoelectronic applications especially in the Infrared and visible fields. Bi2Te3-xSex materials have a direct band gap and can be tuned from 0.1706 eV to 0.7819 eV by varying In composition so emission was tunable from 1.58 to 7.26 micrometers (infrared field), in addition for their direct band gap and in view of their attractive optical properties such conductivity, absorption and reflectivity these materials is considered as promising materials for optoelectronic applications.

本研究采用全势线性缀加平面波（FP-LAPW）方法下的密度泛函理论第一性原理计算，针对硒（Se）组分x分别为0、1、2、3的Bi₂Te₃₋ₓSeₓ合金的结构、电子及光学性质展开了系统研究。本研究采用吴-科恩广义梯度近似泛函（GGA-PBE）计算该合金的基态结构参数，计算结果与已有理论及实验数据吻合良好。借助Tran-Blaha修正Becker-Johnson（TB-mBJ）参数化方案，我们对该合金的电子能带结构与光学常数进行了精准计算。此外，我们还详细分析了该类合金的介电函数、折射率、反射率及光导率特性。研究结果表明，Bi₂Te₃₋ₓSeₓ合金是极具潜力的光电子应用候选材料，尤其适用于红外及可见光领域。Bi₂Te₃₋ₓSeₓ材料为直接带隙半导体，通过改变硒组分可将其带隙从0.1706 eV调控至0.7819 eV，对应发射波长可在1.58至7.26微米（红外波段）范围内调谐；此外，得益于其直接带隙特性以及优异的光学特性（如电导率、吸收率与反射率），该类材料被视为极具应用前景的光电子候选材料。