Hydrogen-induced transport properties of holes in diamond surface layers

Three hydrogen-terminated diamonds with different surface roughness and morphologies have been investigated by conductivity and Hall experiments in the temperature regime 0.34-350 K. The sheet hole densities are weakly temperature dependent above a critical temperature T(c) (20 K less than or equal toT(c)less than or equal to 70 K), below T(c) carriers freeze out. The mobilities of holes show a minimum at T(c) increasing towards higher and even stronger towards lower temperatures significantly up to 400 cm2/V s. A transport model is introduced where holes propagate in the valence band where a disorder-induced tail of localized states is present. (C) 2001 American Institute of Physics.