Electronic properties of H and D doped ZnO epitaxial films

Abstract

ZnO epitaxial films grown by pulsed laser deposition in an ambient of H2 or D2 exhibit qualitatively different electronic properties compared to films grown in vacuum or O2 or bulk single crystals annealed in H2. These include temperature-independent resistivities of ∼0.1Ωcm, carrier (electron) concentrations in the 1018cm−3 range, mobilities of 20–40cm2∕Vs, and negligible (a few meV) activation energies for conduction. These transport properties are consistent with H (D) forming an ultrashallow donor or conduction band states not achievable by postgrowth annealing in H2.