Electronic structure and microwave dielectric properties of Al and N co-doped 3C-SiC

The formation energy, electronic structure and complex permittivities of 3C-SiC with different Al and N codoping levels were studied by the first principles plane wave pseudo-potential method based on the density functional theory. Results showed that the incorporation of N into SiC lowered the formation energy of Al-doped SIC, and that the band gap of co-doped SiC increased with increasing Al level. Both real part epsilon' and imaginary part epsilon '' of complex permittivities for co-doped SiC in the frequency range of 8.2-18GHz increased firstly, and then decreased as the level of Al increased, with the maximum values in epsilon' and epsilon '' for Ala-N complex.