First-principles calculation of structural, electronic, and optical properties of zinc-blende Al_xGa_(1-x)N alloys

摘要

The structural, electronic, and optical properties of zinc-blende Al_xGa_(1-x)N alloys have been calculated based on the density functional theory within the generalized gradient approximation. The calculated lattice constants and band gap bowing parameter are in good agreement with the previous results. According to the calculations of the density of states, we find that the peaks in the conduction band have a tendency of shifting to the higher energy as Al concentration increases, and in the deep valence band, the three peaks become smooth and unite into one peak. Furthermore, the dielectric function, reflectivity, absorption coefficient, and electron energy-loss function are presented and discussed in detail. The peaks in the imaginary part of the dielectric function, the absorption edge and the main peak in energy-loss function are found to have a remarkable blue-shift with the increase of aluminum composition.