DIAMOND-NICKEL INTERFACES - CALCULATION OF THE ELECTRONIC AND ATOMIC-STRUCTURE AND SCHOTTKY BARRIERS

We report the results of first-principles local-density functional calculations of abrupt diamond-nickel interfaces of four types: for both (001) and (111) interfaces we considered atomic geometries with the first nickel layer either in (i) a "tetrahedral" orientation providing a semiconductor-like coordination of the carbon atom at the interface, or (ii) an "in-hollow" orientation providing a more metallic-like coordination. The interlayer distances were optimized in each case. We find that the in-hollow geometries lead to a (hole) Schottky barrier height of 0.9 eV while the tetrahedral arrangements lead to ohmic interfaces (barrier height less than 0.1 eV). The tetrahedral arrangements are favored energetically; analysis of the electronic structure suggests that both the barrier heights and the stabilization energy are related to interface states which retain some diamond dangling-bond character.