Gallium-doped ZnO (ZnO:Ga) films for an alpha-particle scintillator were grown on a sapphire (0001) substrate by radio-frequency magnetron sputtering. Spectral analysis shows that the photoluminescence and scintillation properties of ZnO:Ga films under alpha-particle radiation can be remarkably improved by a post rapid thermal annealing process and also by increasing the film thickness. The surface morphology, crystallinity, and scintillation properties of ZnO:Ga thin films were further improved by in situ growth interruption during the two-step growth process. (C) 2008 The Electrochemical Society.