Vacuum ultraviolet reflectivity measurements of thin-film electroluminescent phosphors

Vacuum ultraviolet reflectivity measurements of three thin-film electroluminescent phosphors, zinc sulfide (ZnS), strontium sulfide (SrS), and strontium-calcium thiogallate (Sr0.45Ca0.55Ga2S4), are reported using thin-film samples. Measured ZnS reflectivity peak positions are in agreement with values previously reported in the literature. SrS room temperature reflectivity measurements are found to be consistent with previously reported low temperature measurements. Reflectivity measurements of Sr0.45Ca0.55Ga2S4 are reported for the first time; the reflectivity spectrum is found to rise monotonically above the band gap and to exhibit almost no structure, except for a small shoulder at similar to 6.8 eV and a single, broad peak at similar to 8.5 eV. The unusual nature of the Sr0.45Ca0.55Ga2S4 reflectivity spectrum is attributed to positional disorder in the stoichiometric thiogallate film. (C) 1996 American Institute of Physics.