The Effect on the Electric Structure and Optical Properties of Ca<sub>2</sub>Ge Bulk with Sr-Doping

Abstract

The electronic structure and the optical properties of Ca 2 Ge have been calculated by the first-principles pseudo potential method. The results of the electric structure show that Ca 2 Ge bulk is a direct semiconductor with the band gap of 0.306 eV, the conduction band is mainly composed of Ca 3d, the valence band is mainly composed of Ge 3p. With Sr-doping, Ca 2 Ge bulk is a direct semiconductor with the band gap of 0.350 eV, the conduction bands are mainly composed of Ca 3d and Sr 3d, the valence bands are mainly composed of Ge 3p and Sr 3d. The results of the optical properties show that the dielectric constant of Ca 2 Ge bulk is reduced from 21.52 to 13.94, the reflectivity is decreased, and the absorption is increased with Sr-doping. The optical properties are improved with Sr-doping, the results offer theoretical guide for the optical properties control of Ca 2 Ge.