Microstructure and properties of epitaxial antimony-doped p-type ZnO films fabricated by pulsed laser deposition

Antimony-doped p-type ZnO films epitaxially grown on (0001) sapphire substrates were fabricated by pulsed laser deposition at 400–600°C in 5.0×10−2Torr oxygen without postdeposition annealing. The films grown at 600°C have among the highest reported hole concentration of 1.9×1017cm−3 for antimony doping, Hall mobility of 7.7cm2∕Vs, and resistivity of 4.2Ωcm. Transmission electron microscopy reveals that the p-type conductivity closely correlates to the high density of defects which facilitate the formation of acceptor complexes and the compensation of native shallow donors. The thermal activation energy of the acceptor was found to be 115±5meV and the corresponding optical ionization energy is ∼158±7meV.