Preparation of thin films of perovskite-type YAlO3:Gd3+–Pr3 + UV phosphors

Abstract

Thin films of the perovskite-type YAlO3:Gd3+–Pr3+ UV phosphor were deposited on a silica glass substrate, a perovskite-type SrTiO3 (001) single crystal substrate, and a LaAlO3 (001) single crystal substrate by a radio-frequency sputtering method. All thin films were noncrystalline in the as-deposited state, and crystallized after annealing at 1000°C in air. Then, films on the silica glass and SrTiO3 substrates frequently showed cracks, in contrast with films on the LaAlO3 substrates which led to smooth surfaces. Such YAlO3:Gd3+–Pr3+ thin films on LaAlO3 substrates exhibited a high crystallinity and strong preferential (00l)- and (hh0)-orientations of the crystallites. Consequently, although UV emission at 314nm from Gd3+ was observed under 217nm excitation in all annealed films, the YAlO3:Gd3+–Pr3+/LaAlO3 film gave the most intense UV emission. It was concluded that fine luminescent YAlO3:Gd3+–Pr3+ thin films were obtained especially on LaAlO3 substrates because of the small thermal expansion difference and lattice mismatch between the YAlO3 phosphor and the LaAlO3 substrate.