Photoluminescence characteristics of ZnGa 2O 4− xM x:Mn 2+ (M=S, Se) thin film phosphors grown by pulsed laser ablation

Abstract

Mn-doped ZnGa 2O 4− x M x (M=S, Se) thin film phosphors have been grown using a pulsed laser deposition technique at varying growth conditions. The structural characterization carried out on a series of ZnGa 2O 4− x M x :Mn 2+ (M=S, Se) films grown on MgO (100) substrates using Zn-rich ceramic targets. Oxygen pressure was varied from 50 to 200 mTorr and substrate temperatures were varied from 500 to 700 °C. The lattice constants of the ZnGa 2O 4− x M x :Mn 2+ (M=S, Se) thin film decrease with the substitution of sulfur and selenium for the oxygen in the ZnGa 2O 4. Measurements of photoluminescence (PL) properties of ZnGa 2O 4− x M x :Mn 2+ (M=S, Se) thin films have indicated that MgO (100) is a promising substrate for the growth of high quality ZnGa 2O 4− x M x :Mn 2+ (M=S, Se) thin films. In particular, a remarkable increase of green emission intensity was observed with ZnGa 2O 3.925Se 0.075:Mn 2+ and ZnGa 2O 3.925S 0.075:Mn 2+ films, whose brightness was increased by a factor of 3.1 and 1.4 in comparison with that of ZnGa 2O 4:Mn 2+ films, respectively. Improved PL brightness with Se or S doping is suggested to result not only from improved crystallinity, but also from reduced internal reflections caused by rougher surfaces. The PL intensity and root mean square (rms) roughness behave similarly as a function of oxygen pressure. These phosphors maybe promising for application to the flat panel displays.