Potential Energy Surfaces for H Adsorbed at 4H-SiC{0001} Surfaces

The constant adsorption energy surfaces for hydrogen adsorbed on Si- and C-terminated hexagonal 4H-SiC{0001} surfaces have been calculated within density functional theory framework. The two unreconstructed and one reconstructed √3 × √3 surfaces were taken into account. We show that on all surfaces there is a global energy minimum indicating the most favourable adsorption site corresponding to H atom adsorption on-top of the topmost substrate layer atom. In case of reconstructed surface, there is another small and shallow local minimum. Moreover, the diffusion barrier is much higher at reconstructed surface than at unreconstructed ones.