Influence of annealing temperature and atmosphere on the morphology and luminescent properties of nanostructured materials

The aim of the study was to determine how the temperature and gaseous environment of annealing affect the morphological and luminescent properties of nanostructured zinc oxide (Zn) -based materials. The study was carried out in Ukraine at the National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute". The methodology included chemical deposition from aqueous solutions followed by thermal annealing at 300, 500, and 700 °C in air, nitrogen, and argon. The morphology was analysed by scanning electron microscopy (SEM), the crystal structure by X-ray diffraction (XRD), and the luminescence spectra by photoluminescence (PL) spectroscopy. The results showed an increase in particle size with increasing temperature, regardless of the atmosphere, with a minimum (~45 nm) at 300 °C in argon and a maximum (~112 nm) at 700 °C in air. With increasing temperature, the coverage density decreased, especially under inert conditions, due to nanoparticle aggregation. Correlation analysis showed a strong negative relationship between particle size and emission intensity (r=-0.89) and a positive correlation between coverage density and PL brightness (r=0.76). Thus, it was established that high-temperature annealing in an oxygen atmosphere most effectively improves the luminescent characteristics of ZnO for optoelectronic and sensor applications. The results are of practical significance for the development of high-efficiency optoelectronic and sensing devices.