Optical gain for wurtzite GaN with anisotropic strain in c plane

We calculated band structures of (11̄00)-oriented GaN with various strains. We found that introducing anisotropic strain in the c plane separates heavy- and light-hole bands. We also found that a tensile strain in the (11̄00) plane makes the light-hole band topmost. These two effects result in a reduction in the density of states at the valence-band edge. In this way we can significantly reduce the transparent carrier density to generate gain.