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

• Fine YAlO3:Gd3 +–Pr3 + films were obtained on LaAlO3 single crystal substrates.
• The thin films on the LaAlO3 substrates showed intense UV emission from Gd3 +.
• Close lattice constants and thermal expansion resulted in the fine films on LaAlO3.

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 314 nm from Gd3 + was observed under 217 nm 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.