Ab initio structural and electronic study of metals on diamond (111)-(1×1) surface

Abstract

Metal contacts on clean diamond surfaces have been studied using ab initio Density Functional Theory. Five metals, i.e., gold, titanium, tantalum, vanadium and palladium on these surface were studied. Gold and palladium were found to form weak bonds on clean diamond (111) surface compared to the other three metals. The clean diamond surface was found to have surface states which were modified by oxygen but removed by hydrogen. Density of states revealed that on adsorption, these metals removed the band gap on clean diamond surface. A peak that was characteristic of diamond was observed at ≈ -11.8 eV. For the clean diamond surface terminated with Au and Pd, states due to Au-2p orbitals were observed at -2.5 eV and ≈ -1.5 eV, while Pd-5s orbitals were located at ≈ -1.7 eV and -0.5 eV. Ti, Ta and V showed unique states at high binding energies; ≈ -38 eV for V, ≈ -34 eV for Ta and ≈ -32.5 eV for Ti, which may explain their strong bonding.