WO3 and WO3-x thin films prepared by DC hollow cathode discharge

Photoactive semiconducting crystalline films of non-stoichiometric tungsten oxides (WO3-x, 0 < x < 3) were deposited by DC hollow cathode discharge from a tungsten nozzle in a reactive Ar + O2 atmosphere. The ratio of tungsten to oxygen in the layer was driven by controlling the O2 flow. All layers were prepared on soda-lime glass substrate (SLG) and on glass substrates coated with an FTO thin film and after deposition were annealed in air or argon atmosphere. The properties of WO3-x layers were analyzed with respect to their potential applications. Surface morphology was analyzed by SEM, qualitative phase analysis by XRD and Raman spectroscopy, chemical composition by EDX and photoactivity of individual samples by linear voltammetry. The layers stoichiometrically closest to WO3 and annealed in an argon atmosphere showed the highest photoactivity response.