Persistent Luminescence of SrAl_2O_4:Eu, Dy Thin Films on Alumina and Sapphire Substrates

摘要

Thermal evaporation was used to synthesize SrAl2O4:Eu, Dy thin films with long lasting phosphorescence on alumina and sapphire substrates. The thin film on the alumina substrate showed a bright afterglow that persisted for as long as 500 seconds after shutting off the UV excitation source, and its photoluminescence intensity was of a comparable order of magnitude to that of the SrAl2O4:Eu, Dy powder. The thin film on sapphire showed a relatively faster decay rate and lower photoluminescence intensity than that on the alumina substrate. In both cases, the film thickness was in the range from 2 to 6.5 mu m. The thin film on alumina had a corrugated surface and internal micro-voids while that on sapphire showed a very dense and uniform surface. The crystal morphology of the thin film is thus considered to be the controlling parameter that contributes to improvements in PL intensity and decay rate.