First-principles study of spontaneous polarization and band gap bowing in ScxAlyGa1 − x − yN alloys lattice-matched to GaN
First-principles calculations are carried out to estimate the spontaneous polarization and the band gap bowing in the ScxAlyGa1 − x − yN alloys lattice-matched to GaN based on the density functional theory together with a pseudopotential plane-wave method. The results indicate nonlinear behavior of the spontaneous polarization and the band gap energies in the ScxAlyGa1 − x − yN alloys similar to that in YxAlyGa1 − x − yN (Shimada et al 2011 J. Appl. Phys. 110 074114). The band gap energies and the magnitude of the spontaneous polarization of ScxAlyGa1 − x − yN is larger than that of YxAlyGa1 − x − yN in a wide range of the mole fraction of Ga. We find that the atomic configuration of Sc affects the magnitude of the polarization in ScxAlyGa1 − x − yN. Another finding is the apparent deviation from Vegard's law of the lattice constants of the ScxAlyGa1 − x − yN alloys lattice-matched to GaN.