First-Principles Investigation on Electronic Structure and Optical Properties of Wurtzite InxGa1-xN Alloys

First-principles calculations of plane wave ultra-soft pseudo-potential method based on the density functional theory (DFT) were used to study lattice constants, band structure, density of states and optical properties of wurtzite InxGa1-xN alloys. The calculated results indicate that the lattice constant gradually increases, the conduction band shifts to low energy direction and the band gap becomes narrower with the increase in In-doped concentration. Meanwhile, the dielectric function moves towards low energy direction, which is red-shift. The first dielectric peak appears near 2.0 eV, and the maximum dielectric peak close to 4.76 eV is found. There are two intersection points at about 5.6 and 9.2 eV. When the photon energy is less than 5.6 eV or higher than about 9.2 eV, the absorption coefficient of InxGa1-xN in low doping concentration (less than 50%) is smaller than that of high doping concentration of InxGa1-xN. However, when the photon energy is located between 5.6 and 9.2 eV, the absorption spectra of InxGa1-xN in low doping concentration are greater than those of high doping concentration. Therefore, the study result shows that InxGa1-xN alloys can be applied as solar cell and the transparent conductive materials.