P和Al掺杂立方相Ca2Si电子结构及光学性质的第一性原理计算

采用基于密度泛函理论的第一性原理平面波超软贋势方法,分别计算了立方相Ca2Si及掺杂P、Al的电子结构和光学性质.结果表明:立方相Ca2Si是带隙为0.55483 eV的直接带隙半导体,价带主要由Si的3p和Ca的3d、4s态电子构成,导带主要由Ca 的3d、4s和Si的3p态电子共同构成,静态介电常数为11.92474,折射率为3.45322.Ca2Si掺P后,Ca2Si转变为n型半导体,其带隙值是0.42808 V,价带主要由Si、Al的3p和Ca的3d、4s态电子构成,导带主要由Ca的3d、Al的3p、3s和Si的3p态电子构成.静态介电常数为7.92698,折射率为2.81549.掺Al后, Ca2Si转变为n型半导体,带隙值是0.26317 eV,费米面附近的价带主要由Si、P的3p和Ca的3d态电子构成,导带主要由Ca的3d 4s、P的3p、3s和Si的3p态电子构成.静态介电常数为17.02409,折射率为4.12603.掺P和Al均降低Ca2Si的反射率,提高Ca2Si的吸收系数,提高Ca2Si的光利用率.说明掺杂能够有效地改变Ca2Si的电子结构和光学性质,为Ca2Si材料的研发和应用提供理论依据.

First-principle Calculation of Electronic Structure and Optical Properties of P and Al Doped Cubic Ca2Si

Energy band structure and optical properties of cubic Ca2Si and P(Al)-doped Ca2Si have been calculated by density functional theory of the first-principles pseudo potential wave method.The results show that the energy band of cubic Ca2Si is a direct semiconductor with the band gap of 0.55483 eV.The valance bands are mainly compose of Si 3p and Ca 3d 4s, the conduction bands mainly composed of Ca 3d 4s and Si 3p, the static dielectric function is 11.92474, the refractive index is 3.45322.The P-doped cubic Ca2Si is an n-type direct semiconductor with the band gap of 0.42808 eV.The valance bands are mainly compose of Si 3p, P 3p and Ca 3d 4s, the conduction bands mainly composed of Ca 3d, P 3p 3s and Si 3p, the static dielectric function is 7.92698, the refractive index is 2.81549.The Al-doped cubic Ca2Si is an n-type with the band gap of 0.26317 eV.The valance bands are mainly compose of Si 3p, Al 3p and Ca 3d, the conduction bands mainly compose of Ca 3d 4s, Al 3p 3s and Si 3p, the static dielectric function is 17.02409, the refractive index is 4.12603.The reflectivity are decrease and the absorption are increase by P(Al)-doped.The electronic structure and optical properties of Ca2Si is effectively modulate by doped, the results offer theoretical data for the experimental study of the cubic Ca2Si.