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 (VAl − ON)-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 К, are formed by the VN 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.
► 3D plots of thermoluminescence emission and excitation spectra in bulk AlN under UV.
► Comprehensive analysis of glow curves in terms of formal general order kinetics.
► We propose the band model of TL processes with VN-traps and (VAl–ON)-complexes.
Source: Diamond and Related Materials