Electro-optical and structural properties of thin ZnO films, prepared by filtered vacuum arc deposition

Thin ZnO films were deposited at room temperature on glass substrates by a filtered vacuum arc deposition system. The electrical, optical and structural properties were investigated as a function of the oxygen pressure in the range of 0.26-0.73 Pa and arc current in the range of 100-300 A. No additional treatment was applied to the samples. Film thickness was in the range of 100-400 nm, depending linearly on the arc current. As-deposited electrical resistivity was in the range of (1-2) × 10^-4 Ωm and the optical transmission of 300-nm-thick films was in the range of 85-95% in the visible and near-IR spectral region. Minimal resistivity of 1.05 × 10 ^-4 Ωm was obtained for a 240-nm-thick film, which had ∼94% transmittance in the visible and near-IR range, and which was deposited at 0.42-Pa oxygen pressure. The relative standard deviation of the measured parameters, determined on a set of seven samples deposited with the same current and pressure was less than 4%. XPS analysis showed that the films were non-stoichiometric both on the surface and within the film, and that the composition was weakly pressure dependent. X-ray diffraction analysis showed the films to be crystalline, with a pressure dependent preferred orientation.