A procedure for producing high-luminance thin-film electroluminescent (TFEL) devices with an oxide phosphor thin-film emitting layer prepared without high-temperature postannealing is described. The TFEL devices were fabricated by depositing an oxide phosphor thin film onto a thick BaTiO3 ceramic sheet insulator using magnetron sputtering and in situ rapid thermal annealing (RTA). The oxide phosphor thin films were deposited by rf magnetron sputtering onto an insulating ceramic sheet mounted on a rotating platform; a thin film was deposited onto the ceramic sheet when it passed over the target, and subsequent in situ RTA was performed on the deposited film when it passed over the halogen lamps. High-luminance green emissions were obtained in TFEL devices using either a Ga2O3:Mn or a ZnGa2O4:Mn thin-film emitting layer prepared under optimized deposition conditions. A ZnGa2O4:Mn TFEL device driven at 1 kHz exhibited a luminance of 200 cd/m(2).