ZnGa2O4 and doped ZnGa2O4 thin film phosphors were prepared by the rf magnetron sputtering method. Deposition parameters were controlled to characterize the deposition mechanism and structural changes. And then the relation between the structure and luminous properties was characterized. To observe the effects of the substrates, thin films were deposited on Si(100), Si(111), and indium-tin-oxide (ITO) coated glass substrates. The orientational transition was observed by varying the substrate temperature. The grain size of ZnGa2O4:Mn thin film deposited on a Si wafer was smaller than that on an ITO/glass substrate, which resulted in higher photoluminescence (PL) intensity. By heat treatment, PL intensity was increased because it eliminated the defects in films and improved the crystallinity.