Dissociative chemisorption of NH3 molecules on GaN(0001) surfaces - art. no. 113301

We performed ab initio calculations to study the structure and the relative stability of hydrogenated GaN(0001) surfaces which may form during the gro wth of gallium nitride using an NH3 nitrogen source. The surfaces that we h ave studied contain H ad-atoms and NH2 ad-complexes adsorbed on GaN(0001). We find that adsorption of H, alone or accompanied by other species, stabil izes the surface of GaN and is able to catalyze the formation of an ideal-l ike geometry. We give an interpretation of this effect in terms of the elec tron band structure. Our results suggest, on microscopic grounds. that roug h surfaces are formed by metal organic chemical vapor deposition under N-ri ch conditions. Ga-rich and H-rich conditions are suggested for the attainme nt of high quality films.