Luminescent Characteristics of ZnGa2O4:Mn Phosphor Thin Films Grown by Radio-Frequency Magnetron Sputtering

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Abstract
Mn-doped ZnGa2O4 phosphor thin films on Si(100) were prepared by rf sputtering at 500° C. Under UV light excitation, the deposited films showed a green emission band with a peak at 508 nm. Monitored at 508 nm, the excitation spectrum of the films showed a primary absorption at 245 nm. The spectra were similar to those of zinc gallate powder but with a larger band width. The films exhibited a high resistivity whether or not under the UV excitation. The possible energy transfer processes occurring in the material were discussed, and the resonance process was considered the dominant mechanism. From the spectral transmittance of undoped zinc gallate films sputtered on quartz glass, the evaluated indirect-transition optical gap was found to be 4.25 eV. The absorption by Ga3+ ions at 245 nm in the excitation spectrum was identified with the band-to-band transition of ZnGa2O4 host lattice.