Copper tungsten oxide (CuxWOy) thin films for optical and photoelectrochemical applications deposited by reactive high power impulse magnetron co-sputtering

• Published in: Journal of applied physics Vol. 132; no. 21
• Main Authors: Hrubantova, A., Hippler, R., Wulff, H., Cada, M., Gedeon, O., Jiricek, P., Houdkova, J., Olejnicek, J., Nepomniashchaia, N., Helm, C. A., Hubicka, Z.
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 07.12.2022
• Subjects: Annealing; Argon; Copper; Crystal structure; Ellipsometry; Fluorine; Gas mixtures; Glass substrates; Magnetron sputtering; Magnetrons; Oxide coatings; Photoelectrons; Raman spectroscopy; Soda-lime glass; Sodium diffusion; Spectrum analysis; Thin films; Tin oxides; Tungsten oxides; X-ray spectroscopy
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/5.0123075

Copper tungsten oxide films are deposited with the help of reactive high power impulse magnetron sputtering (HiPIMS) in an argon/oxygen gas mixture. Two magnetrons, one equipped with a tungsten target and the other with a copper target, are employed. The HiPIMS discharge is operated with a repetition frequency of f = 100 Hz. Pulse widths of 100 and 20  μs separated by 25  μs are chosen for the tungsten and copper target, respectively. Films deposited on two different glass substrates [soda lime glass and fluorine doped tin oxide (FTO) coated glass] are characterized by energy dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, x-ray diffraction, Raman spectroscopy, and ellipsometry. Photoelectrochemical activity was investigated by linear voltammetry. The composition and crystal structure of as-deposited and annealed films are found to depend on the deposition conditions. Annealed films deposited on FTO glass are composed of WO3 and CuWO4 or Cu2WO4 crystal phases. Films deposited on soda lime glass are subject to sodium diffusion into the films during annealing and the formation of Na2W2O7 and Na2W4O 13 phases.