Strain- and Compositional Modulation of the Near-Band-Edge Band Structures of AlN and Its Ternary Alloys with GaN and InN

In this paper, the k- p perturbation theory is adopted to calculate the interband excitonic transition energies and their polarization selection rules in c-plane A1N films, Ga_xAl_1-xN and In_xAl_1-xN alloys modulated by both isotropic biaxial in-plane strain and alloy compositions. It is shown that valence band mixing induced by both strain and alloy composition has dramatic influence on the optical polarization properties. The calculated results provide both good physical insight into the band structure engineering and helpful instructions in the future design of high efficient and novel UV-emitters.