Michio Okajima

Blue-Green Emitting SrS:Ce, Cl Thin-Film Electroluminescent Devices Prepared by Reactive Evaporation Using H2S Gas

SrS:Ce, Cl phosphor films were deposited by evaporating Sr metal and CeCl3 in H2S gas. The crystallinity, luminance, and emission spectra of the films were investigated in relation to the deposition conditions. X-ray diffraction intensity from the (200) plane of the SrS films was found to increase with the substrate temperature when the H2S pressure was kept constant, and had the maximum value at the H2S pressure of 1×10-2 Pa when the substrate temperature was kept constant. The variation of luminance in relation to the H2S pressure and the substrate temperature was similar to that of the (200) diffraction intensity. The luminance of 600 cd/m2 and the maximum emission efficiency as high as 1 lm/W were obtained at 1 kHz 30 µs wide ac pulse excitation for the films deposited at 600°C and H2S pressure of 1×10-2 Pa, although the emission color was not blue but whitish green.