Competing processes with participation of shallow traps in an anion-defective aluminum oxide

Abstract

Anion-defective single aluminum oxide crystals are very sensitive to ionizing radiation and are widely used in thermoluminescent dosimeters [1, 2]. The thermoluminescence curve of these crystals in the temperature interval 300– 900 K contains four thermoluminescence (TL) peaks centered at 350, 480, 730, and 880 K [3, 4]. The peak at 480 K used in dosimetric measurements is dominating. High-temperature peaks at 730 and 880 K are caused by deep traps whose occupation, as demonstrated in a number of works, influences significantly the TL dosimetric peak [3]. The TL peak at 350 K is caused by shallow trap levels. Interest in the shallow trap levels is caused by the fact that these traps can be competitive to the dosimetric centers. Despite the shallow traps were mentioned in many works (for example, see [5, 6]), their TL kinetics and the influence of anion-defective α-Al2O3 crystals on the thermoluminescence and dosimetric properties have not yet been studied in detail. In the present study, the kinetics of the TL peak at 350 K and processes of interaction of shallow and dosimetric traps in aluminum oxide single crystals are investigated.