Thin-film ZnGa2O4:Mn2+ phosphors were grown on quartz substrates through radio frequency magnetron sputtering method. Film phosphors were annealed at different temperatures under reducing ambient. Three microstructural factors of crystallinity, surface roughness, and stoichiometry were strongly dependent on annealing temperatures, and they affected strongly the luminescent properties of film phosphors. The best luminescent intensity was found at annealing temperature of 800 degrees C where three competing factors were optimized. (c) 2007 Elsevier B.V. All rights reserved.