La掺杂AgSnO_2触头材料导电性能的第一性原理分析

First-principles analysis of conductivity of La-doped AgSnO_2 contact material

Ag SnO_2是一种较为理想的Ag Cd O替代材料,但由于其中SnO_2近乎绝缘,使得触头材料的接触电阻增大,故改善SnO_2的导电性是急需解决的重大难题。采用基于密度泛函理论的第一性原理赝势法,通过建模的方法,分别建立不同比例(50%、25%、16.67%、12.5%、8.34%)La掺杂的SnO_2晶胞模型,并计算分析其晶格常数、电荷布居、能带结构和态密度等性质。结果表明,La掺杂后触头材料中的SnO_2仍属于直接带隙半导体材料,但其禁带宽度变小,载流子浓度变大,使得材料的导电性增强。当La掺杂比为16.67%时导电性最佳。

Ag SnO_2 is an ideal substitute material for Ag Cd O electrical contact material. However, due to the near insulation of SnO_2, the contact resistance of this material increases, so improving the electrical conductivity of SnO_2 is an important problem to be solved. By using the first-principle method based on the density functional theory, different proportions（50%, 25%, 16.67%, 12.5%, 8.34%） of La doped SnO_2 were established respectively, then lattice constant, Mulliken population, band structure and density of states were calculated. The results show that La doped SnO_2 is also direct band gap semiconductor material, the band gap becomes smaller, the carrier concentration becomes larger, and the conductivity is enhanced. The doping ratio is 16.67% when the conductivity is the best.