La掺杂SrTiO3电子结构的密度泛函理论研究

A study on electronic structure of La-Doped SrTiO_3 by density function theory

目的研究La掺杂对SrTiO_3体系电子结构和导电性的影响。方法采用基于密度泛函理论(DFT)框架下的第一性原理平面波超软赝势方法。结果La掺杂后,体系总体态密度只是向低能方向进行了刚性平移,费米能级进入导带,简并化加剧,刚性能带模型仍然适用于Sr_(1-x)La_xTiO_3体系;由于Burstein-Moss移动效应,光学带隙明显展宽,在导带底出现大量由La原子贡献的自由载流子-电子,改善了SrTiO_3的导电性能。结论La掺杂对SrTiO_3的导电性起着非常重要的作用。

Aim To study the effect of La doping on the electronic structure and conductivity of SrTiO3. Methods Using the first principles calculation of plane wave ultra-soft pseudo-potential based on the density function theory. Results Due to the electron doping,the Fermi level shifts into conduction bands and the system exhibits n-type degenerate semiconductor features. It is suggested according to the density of states （DOS） of Sr1-xLaxTiO3 （x = 0. 125 and 0. 25 ） that the band structure of La doped SrTiO3 can be described by a rigid band model. At the same time, the DOS shifts towards high energies and the optical band gap is broadened. There are lots of free electrons provided by the impurity atoms in the bottom of conduction band and the conductivity of SrTiO3 is well improved. Conclusion It is possible to improve the conductivity of SrTiO3 by La doping.