Thermoluminescence of deep electron and hole traps in irradiated sapphire

The photo-induced and photo-transferred thermoluminescence of sapphire crystals testifies in favor of the existence of deep traps for charge carriers in crystals. These traps which fill up under the ionizing irradiation of a crystal are not emptied by heating of the crystal up to 700 K. The traps of both signs exist, and their concentrations are very large, estimated at approximately 10¹⁷ - 10¹⁸ cm^-3. They are very stable, are preserved for years, and are annealed at 1000 K. We offer as one hypothesis that under the ionizing irradiation of sapphire crystals a lattice defect of anew kind might be created: a quasi-atom, which has as its core a self-trapped electron with a hole spread around.