La、Bi共掺杂Ag/SnO2触头材料导电性能的理论分析

Theoretical Analysis of Conductive Properties of La,Bi Co-doped Ag/SnO2 Contact Materials

通过CASTEP软件计算了La、Bi共掺杂SnO2的电子结构和导电性能,分析了晶格常数、能带结构、态密度和电荷布局。分析结果表明,共掺杂后的材料仍为直接带隙半导体材料,共掺杂后晶胞体积增加,La的5p和Bi的6s、6p电子态进入导带部分,使导带底向低能端移动,费米能级进入价带顶,带隙变小,载流子只需较小的能量就可以从价带跃迁至导带,与La,Bi单掺杂相比,SnO2的导电性进一步增强。该仿真结果与已有的实验结果相互验证,为获得导电性优良的Ag/SnO2触头材料提供了理论支持。

Electronic structure and electrical conductivity of(La,Bi)codoped SnO2 were calculated by CASTEP software.The lattice parameters,band structure,density of states and charge density were analyzed based on the calculation.The results have shown that the codoped material is still a direct bandgap semiconductor material.After codoping,the unit cell volume increases.The 5 p state of La and the 6 s、6 p states of Bi inserts into the conduction band,which leads to the shift of the conduction band bottom to lower energy zone.Fermi level enters the top of the valence band and narrowing the band gap.The activation energy of the carrier from the valence band to the conduction band decreases.Comparing with La or Bi single doping,SnO2 conductivity is further enhanced.The theoretical results are validated with the existing experimental results,which provide a theoretical support for Ag/SnO2 contact materials with excellent conductivity.