UV light induced processes in pure and doped AlN ceramics

AlN ceramics samples, pure and doped with Y₂O₃, Eu₂O₃ and GaN, and produced from the same AlN powder, were studied for photoelectric effect, photoluminescence spectra and kinetics and thermoluminescence under irradiation with UV light from above- and below-bandgap spectral region. Common properties of all studied samples were found, such as presence of the complex UV-Blue and Red emission bands in PL and TL emission due to oxygen-related defects and manganese impurities, correspondingly; a new emission band at 320 nm, which is present in PL and absent in TL emission spectrum and is assigned to an oxygen-related centre; luminescence decay comprised of superposition of exponents of various duration from nanoseconds to hundreds of minutes. Among the studied samples the dopant-related luminescence was observed only in AlN:Eu₂O₃ at 525 nm. No effect of the dopants on fading rate of the stored TL signal was observed. Such properties of the PL and TL as luminescence intensity and relative contribution of the emission bands manifested by individual samples were explained by influence of the dopant type and ceramics sintering procedure on generation and recharging of the intrinsic and impurity defects.