Identification of the deep-level defects in AlN single crystals: EPR and TL studies

Abstract

X-band electron paramagnetic resonance studies were performed on three different types of AlN single crystals. These studies revealed the presence of two different types of shallow donors, oxygen located in the N site of the AlN lattice and carbon or silicon located in the Al site. These findings are supported by the observation of the light-induced EPR signals with almost similar slightly anisotropic g factors typical for shallow donor in AlN, but strongly different anisotropic EPR line-width ΔB. Distribution of the wave-function density of the unpaired donor electron for both shallow donors is discussed. Moreover, findings related to the deep-donor of the V N centers are presented. The V N center EPR spectra intensity increased drastically after the x-ray irradiation of the sample. The annealing results in recombination thermoluminescence and the deep donor (V N) energy level was estimated to be about 0.75 eV.