Synthesis and spectroscopic properties of aluminum oxynitride doped with 3d-metal ions: The case of γ-AlON:Ti

Polycrystalline samples of γ-aluminum oxynitride (Al5O6N) doped with titanium ions have been prepared via high temperature annealing of mixtures of AlN, Al2O3 and TiO2. Electronic structure and spectroscopic properties of AlON:Tin+ were studied for the wide range of Tin+ concentrations varying from 0.05 to 5.0 at% vs. aluminum. The solubility limit of Tin+ ions in Al5O6N can be estimated at the level of 0.2–0.5 at% and an excess of Tin+ forms TiN phase. Following the XPS data, titanium exists in three different coordination environments including [TiO6], [TiOxN6–x] and [TiN6]. The optical gap evaluated from the diffuse reflectance spectra is consistent with the earlier defined for γ-AlON and shows the tendency to decrease at higher titanium content. Pulsed cathodoluminescence spectra show several bands originating from intrinsic and impurity defects. The titanium doping of γ-AlON results in overall reducing of optical and luminescence properties.