Luminescence characteristics of ZnGa2O4 thin film phosphors grown by pulsed laser deposition

ZnGa2O4 thin film phosphors have been deposited using a pulsed laser deposition technique on Si(100) substrates at a substrate temperature of 550 degreesC with various oxygen pressures and post-annealing temperatures. The structural characterization was carried out on a series of ZnGa2O4 films grown at an oxygen pressure range of 50-300 mTorr, and subsequently post-annealed at 600 and 700 degreesC. The optimum oxygen pressure for luminescent characteristics was about 100 mTorr. The luminescent spectra show a broad band extending from 350 to 600 nm peaking at 460 nm. A post-annealing treatment of ZnGa2O4 thin films led to the different shape of luminescent intensity and grain size. beta-Ga2O3 phase appeared at an annealing temperature of 600 degreesC and increased with increasing annealing temperature. We have also investigated the effect of the ligand field strength on the resultant energy levels for ZnGa2O4 thin film phosphor. The annealing process at different temperatures may lead to different dominant emissions. (C) 2002 Elsevier Science B.V. All rights reserved.