Density functional theory calculations were made of the binding and diffusion of Ga and N adatoms on GaN (00▪1) and (00▪¯1) surfaces under various conditions, including stoichiometric and Ga-rich surfaces, as well as in the presence of electron-hole pairs induced by light- or electron-beam irradiation. It was found that both Ga-rich conditions and electronic excitations caused a significant reduction of the adatom diffusion barriers, as required to improve the quality of the material. However, the 2 effects were non-additive, as the influence of electron-hole pairs was found to be less important for the more metallic cases.

Adsorption and Diffusion of Ga and N Adatoms on GaN Surfaces - Comparing the Effects of Ga Coverage and Electronic Excitation. N.Takeuchi, A.Selloni, T.H.Myers, A.Doolittle: Physical Review B, 2005, 72[11], 115307 (5pp)