First-principles investigation of lattice constants and bowing parameters in wurtzite Al_xGa_1−xN, In_xGa_1−xN and In_xAl_1−xN alloys

First-principles calculations, by means of the full-potential augmented plane wave method using the local density approximation, were carried out for the structural and electronic properties of the Al_xGa_1−xN, In_xGa_1−xN and In_xAl_1−xN alloys in the wurtzite structure. We have investigated the lattice parameters and band gap energies. The lattice constants a and c are found to change linearly for the Al_xGa_1−xN alloy, while for both In_xGa_1−xN and In_xAl_1−xN alloys the lattice parameters, a, exhibit an upward bowing. The calculated band gap variation for the three alloys exhibit a downward bowing of 0.71 eV, 1.7 eV and 4.09 eV for Al_xGa_1−xN, In_xGa_1−xN and In_xAl_1−xN, respectively.