Excitation mechanism of the Cr3+ luminescence center in SrTiO3

From thermoluminescence (TL), thermally stimulated currect (TSC), and photoluminescence and photoconductivity kinetic response measurements, the excitation mechanism of the Cr3+ luminescence center in SrTiO3 is explored. Based primarily on the strong correlation between TSC and TL, it is concluded that the dominant excitation mechanism is a charge-transfer process, although a contribution from a resonance-transfer process cannot be completely ruled out. The superficial differences which exist between photoluminescence and photoconductivity kinetics can be accounted for completely within the framework of a charge-transfer model by recognizing that the photocurrent is controlled primarily by the electron traffic through the conduction band, while the photoluminescence is controlled primarily by the hole traffic through the luminescence center.