Hydrogenated Al-doped ZnO (H:AZO) thin films were deposited on glass substrates at room temperature by radio-frequency magnetron sputtering at various hydrogen flow rates. The addition of hydrogen improved the resistivity of the H:AZO films significantly. A thin insulating layer was produced on H:AZO films by atmospheric pressure plasma with Ar/O(2) reactive gas. The resistivity degenerated and the optical band gap of the oxygen plasma-treated H:AZO films decreased from 3.7 eV to 3.4 eV. This was attributed to a decrease in the hydrogen concentration at the film surface according to elemental depth analysis. (C) 2010 Elsevier B.V. All rights reserved.