Effect of substrate heating and bias on the DC reactive magnetron sputtering of ZnO using Ar-H2O plasma

Abstract

The effect of varying substrate bias and temperature conditions for zinc oxide (ZnO) film deposition using water vapor plasma was investigated. Near surface plasma parameters were measured using a single Langmuir probe, and was correlated to the film properties. The substrate bias polarity modified the incident energetic species during film deposition, while the magnitude modified the incident particle energy. These changes were found to reflect at the film properties, particularly in the crystallite size and surface resistivity. The band gap was measured to be 3.32 eV, indicating the shallow donor doping of hydrogen (H). The substrate heating affected the adsorption behavior of water near the substrate surface. Increasing the temperature resulted to a localized increase in ion density, and the growth of other ZnO orientations after crossing a threshold temperature. The higher substrate temperature decreased the film's resistivity, while the shallow donor doping and transmittance of the films were nearly constant.