Barrier Heights of Metal Contacts on H-Terminated Diamond: Explanation by Metal-Induced Gap States and Interface Dipoles

Barrier heights reported by Kawarada et al. for metal contacts on H-terminated p -diamond surfaces are by approximately 1 eV smaller than what was found earlier with the same metals on clean p -diamond surfaces. The latter data are explained by the model that the continuum of metal-induced gap states determines the barrier heights in metal-semiconductor contacts and the charge transfer across such interfaces may be described by the difference of the metal and semiconductor electronegatives. Both sign and magnitude of the H-induced lowering of the barrier heights on p -diamond are explained by an interface layer of additional H–C dipoles.