Exciton Luminescence of YAlO[sub 3] Single Crystals and Single-Crystal Films

Abstract

The paper reports on a study of exciton luminescence in single crystals (SCs) and single-crystal films (SCFs) of YAlO3, which have substantially different concentrations of vacancy-type and substitutional defects, under excitation by synchrotron radiation near the fundamental absorption edge. The radiative annihilation of excitons in SCFs was shown to occur primarily at regular perovskite lattice sites and to be accompanied by luminescence in a band peaking at λmax = 295 nm with τ = 5.2 ns. In contrast to SCFs, the radiative exciton decay in YAlO3 SCs takes place predominantly near vacancy-type defects (F+ and F centers) and is accompanied by luminescence in the bands at λmax = 350 nm (τ = 2.5 ns) and 440 nm (τ1 = 1.9 ns, τ2 = 30 ms). Photoexcitation in the 175-nm band of YAlO3 SCs revealed photoconversion of the centers F → F+.