Theory of the clean and hydrogenatedAl2O3(0001)−(1×1)surfaces

Abstract

We present the results of a first principles investigation of the equilibrium properties of c-plane $\alpha -{\mathrm{Al}}_2{\mathrm{O}}_3$ surfaces. The stable structure for the $1\times 1$ clean surface is Al terminated with a stoichiometric composition, while other terminations are unstable independent of surface preparation conditions. We discuss the implications of our results in the frame of possible extended reconstructions. For 1 monolayer of H coverage, we find that the preferred structure has OH dimers both perpendicular and nearly parallel to the surface. H-terminated surfaces may form in suitable preparation conditions. We discuss our results in terms of water adsorption and atomic layer epitaxy of $\alpha -{\mathrm{Al}}_2{\mathrm{O}}_3\mathrm{}\left(0001\right).$