Wetting Silicon Carbide with Nitrogen: A Theoretical Study

In order to model the early stages of nitride growth on cubic silicon carbide, we have studied the deposition of atomic nitrogen on the Si-terminated SiC(001) surface, using first-principles molecular dynamics. For many configurations with coverages less than 1/2 monolayer, N is preferably adsorbed at zinc blende sites and forms nitridized Si pairs. At one monolayer, N forms instead hydrazinelike N₂Si₄ complexes, yielding a fully coated, inert substrate which inhibits growth. In this configuration, full nitridization of the surface is energetically favored. Interface mixing and formation of C-N bonds are observed when mimicking the deposition of positively charged nitrogen ions.