Structure and energetics changes during hydrogenation of 4H-SiC{0001} surfaces: a DFT study

The changes in the atomic and electronic structure of Si- and C-terminated hexagonal SiC{0001} surfaces resulting from on-surface and subsurface hydrogen adsorption have been studied within the density functional theory framework. Hydrogen coverages ranging from a submonolayer to one monolayer were considered. Our results show that a monolayer of adsorbed H almost completely suppresses the relaxation of the SiC surface atomic layers. On both terminations H binds strongly to the surface and the binding is about 2 eV stronger in on-surface sites than subsurface. Hydrogen binding to the C-terminated surface varies very little with coverage and is distinctly stronger than to the Si-terminated surface.