N-rich B-C-N layers: From segregated alloy to solid solution

We perform a theoretical study of nitrogen-rich B-C-N graphene-type alloys through a combination of Monte Carlo and ab initio methods. Different from the B/N = 1 limit, where both calculations and experiments indicate segregation into BN and C regions, the simulations of the N-rich alloys result in solid solution materials, with isolated carbon substituting boron sites of BN. We show that this is a consequence of the competition between bond energies. As a result of the solid solution morphology, the electronic structure of N-rich alloys depict a approximate to 1.5 eV wide, half-filled carbon impurity band that would result in either metallic behavior or disorder-induced semiconducting behavior with a mobility gap.