The luminescence enhancement mechanism of a white ZnGa2O4 phosphor screen with an In2O3 buffer layer was studied by growing ZnGa2O4 with optimal sputtering parameters and varying the deposition conditions of In2O3. A ZnGa2O4 film with better crystallization and smaller grains was obtained when it was deposited on In2O3. These qualities revealed that the resistivity of the phosphor screen was correlated with the surface roughness and resistivity of the In2O3 buffer layer. The photoluminescence spectra of the phosphor screen revealed that the ligand field of the Ga luminescence center was not modified when the In2O3 deposition parameters were varied; however, the emission intensities were altered due to the electron-transition probability in the Ga energy levels changing with the crystallization of phosphor. A significantly enhanced emission from the phosphor screen was observed by improving the crystallization, surface morphology, and resistivity of the prepared ZnGa2O4 phosphor film with the In2O3 buffer layer. (c) 2007 The Electrochemical Society.