Sr掺杂对正交相BaSi_2能带结构和光学性质的影响

Effects of Sr Doping on Band Structure and Optical Properties of Orthorhombic BaSi_2

利用密度泛函理论赝势方法,采用第一性原理对Sr掺入正交相BaSi_2晶格的影响进行了计算。首先,对BaSi_2型的Ba_(1-x)Sr_xSi_2(x=0.125)进行几何优化,接着对其能带结构和光学性质进行了计算。结果表明:Sr原子的替代具有择位性,Sr倾向替换BaI位的Ba原子。与块体BaSi_2相比较,能带宽度变大了,但仍为间接带隙半导体。Ba_(1-x)Sr_xSi_2(x=0.125)的静态介电常数和折射率的值都变大了,介电函数虚部第一峰值的出现位置、吸收谱、复折射率和光电导率都向低能方向移动。

Effects of Sr incorporation into the orthorhombic BaSt： lattice was calculated by first - principle pseudopotential method based on the density function theory（DFT）. At first, Ba1 xSrxSi： （x = 0. 125） with the BaSt： type are geometrically optimized. Band structure and optical properties of Ba1 xSrxSi： （x = 0. 125） are calculated. The results show that BaI site will be preferentially replaced by Sr rather than the Bail sites. Ba1 xSrxSi： （x = 0. 125 ） is an indirect gap semiconductor with wilder band gap. The value of the states of dielectric function and refractive index are increased. The speturm of absorption, complex refractive index, optical conductivity and the first value of image part of dielectric funvtion of Ba1 xSrxSi： （ x = 0. 125 ） shift to the low - energy.