Inversion Domain and Stacking Mismatch Boundaries in GaN

We present first-principles calculations of domain wall energies for inversion domain boundaries and stacking mismatch boundaries in GaN. We find a low-energy inversion domain boundary in which each atom remains fourfold coordinated without the formation of Ga-Ga or N-N bonds. This boundary, denoted IDB*, does not induce electronic states in the band gap and would therefore not adversely impact photoluminescence efficiency. The stacking mismatch boundary has a higher formation energy than IDB*, and gives rise to occupied N-derived interface states in the band gap.