Study on the Electronic Structure and Optical Properties of (K, Rb, Cs, Fr) Doped CoSi Based on the First Principle

Abstract

In this paper, the band structure, density of States and optical properties of CoSi, K, Rb, Cs and Fr doped CoSi are calculated by first principles. It is found that the bottom and top of the conduction band pass through the Fermi level before and after doping, showing metal properties. The static permittivity of undoped CoSi, K, Rb, Cs and Fr doping is 28.9,154,168,110,105 respectively, which indicates that the static permittivity is improved after doping the refractive index of doped K, Rb, Cs and Fr increases compared with that of undoped CoSi. After doping, the maximum imaginary part of dielectric constant is 18.4; 608; 56; 32.9; 31 respectively.CoSi, K-CoSi, Rb-CoSi, Cs-CoSi and Fr-Cosi have strong absorption of light in the far ultraviolet region, and the maximum absorption coefficients are 3.83, 3.69, 3.37, 3.34 and 3.33 respectively. The maximum reflection peak of undoped CoSi is 0.807, that of K-doped system is 0.774, that of Rb-doped system is 0.713, that of Cs-doped system is 0.731, and that of Fr-doped system is 0.758. It can be seen that the reflectivity of doped CoSi decreases, and the reflectivity of Rb-doped system is the smallest Compared with the undoped system, the photoconductivity of the doped system moves to the high energy region, resulting in a blue shift.