Interaction of water molecules with SiC(001) surfaces

We have investigated the interaction of water molecules with the polar Si- and C-terminated surfaces of cubic silicon carbide by means of ab initio molecular dynamics simulations at finite temperature. Different water coverages were considered, from 1/4 to a complete monolayer. Irrespective of coverage, we find that water dissociates on the silicon-terminated surfaces, leading to important changes in both its structural and electronic properties. On the contrary, the carbon-terminated surface remains inert when exposed to water. We propose experiments to reveal the ionic and electronic structure of wet Si-terminated surfaces predicted by our calculations, which at full coverage are notably different from those of hydrated Si(001) substrates. Finally, we discuss the implications of our results for SiC surface functionalization.