Stability and electronic structure of ordered Si0.75Ge0.25C alloy

Abstract

Calculations are performed on the stability and electronic structure of an ordered Si0.75Ge0.25C alloy within the generalized gradient approximation using the first-principles method. The alloy is stable at zero pressure and temperature, with its lattice constant 4.34 Å close to that of cubic SiC and bulk modulus 223 GPa. An analysis of the band structure and density of states shows the cubic alloy to be an indirect semiconductor with a wider band gap compared to SiC and therefore is a candidate material that can function in heterostructure applications. When combined with cubic SiC to form heterostructure bipolar transistors, an enhancement coefficient 2×104 for current gain β would be expected relative to the SiC homojunction bipolar junction transistors at room temperature.