First-principles study of doping and distribution of Si in TiC

In this work, first principles calculations have been performed to study the doping and distribution of Si atoms in TiC lattice. The results confirm that Si atoms prefer to occupy Ti sites and their segregation on the TiC crystal surface may occur. But in the presence of carbon vacancies on the surface, Si atoms tend to be chemically adsorbed around the vacancies rather than occupy the carbon sites. It is also shown that the diffusion of Si may be very difficult in stoichiometric TiC, in particular the diffusion from bulk to surface. However, the carbon vacancies can considerably decrease the energy barrier and enhance the diffusion of Si atoms.