Thermoluminescence kinetics of oxygen-related centers in AlN single crystals

Abstract

Excitation and emission spectra of thermoluminescence (TL) in bulk aluminum nitride single crystals irradiated by UV have been studied. TL has been found to be most effectively excited by the 5.04 eV photons. The 3.44 eV band caused by recombination processes with oxygen-vacancy (V Al - O N)-centers dominates in the TL spectrum. Besides, the 2.91 and 2.0 eV emissions have been also observed. The TL mechanisms have been quantitatively analyzed in terms of formal kinetics of general order. On the basis of the obtained values and from their comparison with literature data it has been concluded that the main traps of charge carriers, responsible for the TL peak at 470 K, are formed by the V N vacancy. To interpret the observed regularities, the model of TL has been proposed, which satisfactorily agrees with independent data for thermally and optically stimulated processes in aluminum nitride. © 2012 Elsevier B.V. All rights reserved.