Surface properties of the refractory metal-nitride semiconductor ScN: Screened-exchange LDA-FLAPW investigations

Density-functional theory calculations employing the screened-exchange local-density approximation (SX-LDA) with the full potential linearized augmented plane-wave method have recently shown that the relatively unexplored refractory nitrides ScN, YN, and LaN are semiconductors. For the ScN(001) surface, the present calculations predict that the ideal-relaxed surface has the lowest formation energy for most of the range of the allowed chemical potentials - and is semiconducting - while N-deficient structures, which are predicted to form for Sc-rich conditions, are metallic in nature. Compared to the LDA surface-state band structures, the SX-LDA selectively pushes down the valence bands for the Sc-terminated surface and pushes up the conduction bands for the N-terminated structure.