This study systematically investigates the microstructural evolution of nanoparticle-based CuO, WO3, and composite 'CuO-WO3' thin films induced by their post-deposition annealing. The films were reactively deposited using a magnetron-based gas aggregation technique, with the composite films consisting of alternating monolayers of CuO and WO3 nanoparticles. After deposition, the films were annealed in synthetic air at temperatures ranging from 200 to 400∘C and characterized using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. Annealing of the CuO films led to the most pronounced changes associated with a gradual enhancement of crystallinity accompanied by significant particle growth with increasing annealing temperature, while the WO3 and CuO-WO3 films were more thermally stable to crystallization and particle growth. Notably, at 400∘C, the CuO--WO3 films crystallized into a novel γ-CuWO4 phase. The annealed films were further evaluated for their gas-sensing performance upon H2 exposure and the obtained results were analyzed in relation to film properties and the microstructural evolution induced by annealing.
@article{arxiv.2502.15497,
title = {Thermally-induced microstructural evolution in nanoparticle-based CuO, WO$_3$ and CuO-WO$_3$ thin films for hydrogen gas sensing},
author = {Kalyani Shaji and Stanislav Haviar and Petr Zeman and Michal Procházka and Radomír Čerstvý and Nirmal Kumar and Jiří Čapek},
journal= {arXiv preprint arXiv:2502.15497},
year = {2025}
}