Luminescent properties of SrGa2S4:Eu thin film phosphors deposited by two electron beam evaporation

SrGa2S4:Eu thin film phosphors have been deposited on quartz glass substrates at substrate temperatures of 350–450 8C by multi-source deposition method in which two electron beam (2EB) evaporation sources were used. The films were annealed between 750 and 850 8C for 30 min in H2S atmosphere after the deposition. It was shown by XRD measurement that SrGa2S4 phase was not formed but crystalline GaS was included in an as-deposited film, therefore, PL and CL due to SrGa2S4:Eu were not observed. The SrGa2S4 phase was formed by the annealing. Photoluminescence (PL) and cathodoluminescence (CL) spectra of all annealed films showed green emission peaked at about 530 nm. CL luminance of all the films increased as the substrate temperature was increased. But the dependence on annealing temperature was not observed. So CL luminance depended only on substrate temperature during deposition. However, the CL luminance did not depend clearly on the annealing temperature between 750 and 850 8C. The SrGa2S4:Eu film deposited at 450 8C and annealed at 850 8C for 30 min showed a CL luminance and CIE coordinates of 1700 cd/m2 and (0.27, 0.67), respectively under excitation with 3 kV and 60 mA/cm2.