Different Roles of a Boron Substitute for Carbon and Silicon in β-SiC

The first-principles numerical simulation is employed-to calculate the effect of replacement of carbon and silicon with boron on the electronic structure and optical properties of β-SiC.Mulliken analysis shows that the B impurity bond lengths shrink in the case of Bsi,while they expand with reference to Bc.In addition,Bsi contains C-C,Si-Si and B-Si bonds.The calculated results show that the two systems of Bc and Bsi apply different dispersion.Bc is in accordance with the Lorentz dispersion theory while Bsi follows the Drude dispersion theory.Theoretic analysis and quantitative calculation are used for conductivity spectra in the infrared region.