Charge transfer processes and dynamic equilibrium of electronic state occupancies in optically excited SrTiO 3:Cr crystals

Abstract

Spectral and kinetic measurements of 2E → 4A 2 photoluminescence (PL) in SrTiO 3 crystals containing small amounts of Cr were performed and a strong effect of IR illumination on the PL was observed. The dominant photoionization mechanism of Cr 3+ PL excitation was established. The locations in the SrTiO 3 band gap of Cr 3+ donor levels (1.85eV below the bottom of the conduction band) and of Cr 4+ acceptor levels (1.4 eV above the top of the valence band) were found. A new mechanism of optical erasing of burnt spectral holes of the R lines in SrTiO 3: Cr was determined.