AN INTERACTIVE PROCESS IN THE MECHANISM OF THE THERMALLY STIMULATED LUMINESCENCE OF ANION-DEFECTIVE ALPHA-AL2O3 CRYSTALS

The role played by deep traps in the appearance of specific features o f the thermally stimulated luminescence (TL) of anion-defective alpha- Al2O3 single crystals is reported. The existence of deep traps has bee n proved by direct observations of the TL peaks associated with these traps. From the experimental evidence it is adduced that the degree of occupancy of the deep traps affects the basic features of the main TL peak at 450 K. A model of an interactive trap system is proposed. The main difference of this model from those described in the literature is that it allows for the temperature dependence of the probability of the charge carriers to be captured at the deep traps. The proposed mo del was used to calculate the basic TL parameters of the main peak (th e TL output and the shape of the glow curve) of the crystals in questi on as a function of the heating rate and the occupancy of the deep tra ps. The calculated values are similar to those observed experimentally . (C) 1998 Published by Elsevier Science Ltd. All rights reserved.