New experimental data illustrating the effect of deep traps on the luminescence properties of anion-defective α-Al2O3 single crystals were presented. It was established that deep traps had electronic nature and their filling occurred through photo-ionization of F centers and was accompanied by F → F+-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 exo-electron emission, and thermally stimulated electrical conductivity.

Mechanism of F-Center Luminescence in Anion-Defective Aluminum Oxide Single Crystals. V.S.Kortov, I.I.Milman, S.V.Nikiforov, V.E.Pelenev: Physics of the Solid State, 2003, 45[7], 1260-6