Cathodoluminescence properties of blue-emitting SrGa2S4:Ce thin-films grown by low-temperature process

The cathodoluminescence (CL) properties of Ce-activated strontium thiogallate (SrGa2S4:Ce) thin films have been investigated aiming towards phosphor screen application in an emissive display under low to medium accelerating voltage (<5 kV) excitation. The SrGa2S4:Ce thin films were grown by multisource deposition using a molecular beam epitaxy system. The growth temperature of the CL phosphor thin films was 472.5 °C, which is the lowest value ever achieved. Several related properties were observed, including the CL spectra, luminance, luminous efficacy, and surface morphology of the thin films. A luminance of 1000 cd/m2 and an efficacy of 1 lm/W were obtained at an accelerating voltage of 5 kV with a current density of 60 μA/cm2. The light-outcoupling efficiency (ηout) of the film was 0.0531. In spite of this small ηout of the films compared to that of powder phosphors, the luminance and efficacy were comparable to the conventional ZnS:Ag, Cl powder phosphor. The average grain size of the films was 0.14 μm×0.04 μm. The high luminance and luminous efficacy of the films with their submicron grain size is useful to realize high-resolution emissive displays.