Features of spectrally resolved thermoluminescence in UV irradiated aluminum nitride microcrystals

The regularities of photo- and thermoluminescence processes in submicrosized AlN crystals with cationic deficiency after UV excitation are studied. The observed emission spectra are a superposition of Gaussian bands with maxima at 3.0 and 2.5 eV. The indicated spectral features are due to electronic transitions involving O$_{\mathrm{N}}$ impurity and ($V_{\mathrm{Al}}$–O$_{\mathrm{N}}$) oxygen-vacancy complexes. According to a quantitative analysis in the framework of the general order kinetics, carrier capture centers based on ($V_{\mathrm{N}}$ nitrogen vacancies have an activation energy of 0.45 eV and are responsible for the forming of the thermally stimulated luminescence with maximum at a temperature of 345 K.