CAN HYDROGEN STABILIZE THE ALPHA-SIC(0001)ROOT-3X-ROOT-3 SURFACE

The paper presents an analysis of the energetics of a few possible can didates for the structural model of the root 3 X root 3 R30 degrees re construction of the alpha-SiC(0001) surface. The analysis is based on the semi-empirical, self-consistent, quantum-mechanical cluster calcul ations of MNDO-type (AM1 parametrization). Clean stoichiometric, Si ri ch and C rich surface structures as well as surfaces saturated by hydr ogen and the hydroxyl groups are examined and particular care is appli ed when comparing energies of the structures with different stoichiome tries. The results confirm the claim that the most favorable model for the reconstruction is here the one where hydrogenated triangles of C atoms saturate the surface silicon dangling bonds. Moreover, the calcu lated energies indicate that the reconstructed surface is a result of the desorption of SiO from the 1 X 1 surface originally saturated by h ydroxyl groups.