Enhanced luminescence in ZnGa2O4-xSx:Mn2+ thin-film phosphors grown on MgO(100) substrate

Mn-doped ZnGa₂O_4-xS_x thin-film phosphors have been grown using a pulsed laser deposition technique at varying growth conditions. Structural characterization was carried out on a series of ZnGa₂O_4-xS_x:Mn²⁺ films grown on MgO(100) substrates using Zn-rich ceramic targets. Oxygen pressure was fixed at 100 mTorr and substrate temperatures were varied from 500 to 700 °C. The results of X-ray-diffraction patterns showed that the lattice constants of the ZnGa₂O_3.95S_0.05:Mn²⁺ thin films decrease with the substitution of sulfur for the oxygen in ZnGa₂O₄. Measurements of photoluminescence (PL) properties of ZnGa₂O_4-xS_x:Mn²⁺ thin films have indicated that MgO(100) is one of the most promising substrates for the growth of high-quality ZnGa₂O_4-xS_x:Mn²⁺ thin films. In particular, the incorporation of sulfur into the ZnGa₂O₄ lattice could induce a remarkable increase of PL. The highest green-emission intensity was observed with ZnGa₂O_3.95S_0.05:Mn²⁺ films, whose brightness was increased by a factor of 3.5 in comparison with that of ZnGa₂O₄:Mn²⁺ films. This phosphor may be promising for application to flat-panel displays. PACS 78.20.-e; 78.55.-m; 78.66.-w