Mechanism of F-center luminescence in anion-defective aluminum oxide single crystals

Abstract
New experimental data illustrating the effect of deep traps on the luminescence properties of anion-defective α-Al2O3 single crystals are presented. It was established that deep traps have electronic nature and their filling occurs through photoionization of F centers and is accompanied by FF+-center conversion. Model concepts were developed that describe the luminescence mechanism in anion-defective aluminum oxide single crystals with inclusion of thermal ionization of the excited F-center states. The validity of the model was supported by experimental data obtained in a study of thermoluminescence, thermally stimulated exoelectron emission, and thermally stimulated electrical conductivity.