Absolute surface energies of polar and nonpolar planes of GaN

Accurate values for absolute surface energies are required to understand bulk and thin-film growth. Using first-principles calculations based on hybrid density functional theory we determine energies for bare and hydrogenated surfaces of wurtzite GaN in polar and nonpolar orientations. We find that the energies of the nonpolar m and a planes are similar and constant over the range of Ga, N, and H chemical potentials studied. In contrast, the energies of the polar planes are strongly condition dependent. We find that the +c polar plane is systematically lower in energy than the -c plane.