Stable highly conductive ZnO via reduction of Zn vacancies

Growth of Ga-doped ZnO by pulsed laser deposition at 200 °C in an ambient of Ar and H2 produces a resistivity of 1.5 × 10−4 Ω-cm, stable to 500 °C. The resistivity can be further reduced to 1.2 × 10−4 Ω-cm by annealing on Zn foil, which reduces the compensating Zn-vacancy acceptor concentration NA to 5 × 1019 cm−3, only 3% of the Ga-donor concentration ND of 1.6 × 1021 cm−3, with ND and NA determined from a degenerate mobility theory. The plasmon-resonance wavelength is only 1060 nm, further bridging the gap between metals and semiconductors.