Authors
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Stefan Jovanovski
Institute of Physics, Faculty of Natural Sciences and Mathematics, University Ss Cyril and Methodius, Skopje, Arhimedova 3, Republic of North Macedonia
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Maja Popović
Department of Atomic Physics, Vinča Institute of Nuclear Sciences - National Institute of Thе Republic of Serbia, University of Belgrade, Belgrade, Republic of Serbia
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Mirjana Novaković
Department of Atomic Physics, Vinča Institute of Nuclear Sciences - National Institute of Thе Republic of Serbia, University of Belgrade, Belgrade, Republic of Serbia
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Vladimir Rajić
Department of Atomic Physics, Vinča Institute of Nuclear Sciences - National Institute of Thе Republic of Serbia, University of Belgrade, Belgrade, Republic of Serbia
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Miha Bukleski
Institute of Chemistry, Faculty of Natural Sciences and Mathematics, University Ss Cyril and Methodius, Arhimedova 5, Republic of North Macedonia
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Marko Erich
4Department of Physics, Vinča Institute of Nuclear Sciences - National Institute of Thе Republic of Serbia, University of Belgrade, Belgrade, Republic of Serbia
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Mimoza Ristova
Institute of Physics, Faculty of Natural Sciences and Mathematics, University Ss Cyril and Methodius, Skopje, Arhimedova 3, Republic of North Macedonia
Abstract
WO3 thin films were prepared by RF sputtering metallic tungsten onto glass substrates, followed by thermal oxidation through annealing in air. This technique is straightforward, cost-efficient, and time-effective, achieving high deposition rates of 16 nm/min on average at 200 W magnetron power for the highly homogeneous W-metallic films. SEM/EDX analysis showed that after annealing at 450ᵒC in air, the RF sputtered 269 nm thick metallic W films with a round grain morphology (~30 nm) turned into 420 nm thick nearly stoichiometric transparent WO3 (tungsten (VI) oxide) film, with a dramatically changed morphology of aggregated crystal rods approximately 1 µm long. XRD and Raman spectroscopy confirmed a biphasic crystal structure, with a dominant monoclinic phase and a minor tetragonal phase. XPS analysis revealed the characteristic W4f7/2 and W4f5/2 electron peaks associated with the W6+ oxidation state, with no evidence of W5+ species, indicating a stoichiometric nature of the WO3 films.
