WO3 thin films prepared by sedimentation and plasma sputtering

- WO3 thin films were grown on FTO by sedimentation and/or magnetron sputtering.
- Orientation of crystallites was dependent on the mode of discharge pulsing.
- The (2 0 0) orientation revealed the highest photocurrents at PEC measurement.
- Combination of sedimentation and magnetron sputtering led to the best results.

Tungsten trioxide (WO3) semiconducting thin films were prepared by (i) sedimentation process, (ii) reactive magnetron sputtering from tungsten target under various modes of plasma excitation and (iii) combination of both methods. All samples were deposited on FTO (fluorine-doped tin oxide) coated glass substrate and were annealed after deposition under open air conditions in 450 °C in order to improve their crystallinity and semiconductor properties. This study deals with a comparison of photo-electro-chemical properties of the layers prepared by the methods mentioned above. After annealing, all the prepared WO3 films revealed monoclinic crystalline structure while the as-deposited samples were amorphous. Different orientation of crystallites was found for different mode of discharge pulsing in plasma prepared samples. The presence of crystalline WO3 is essential for significant photocurrent response. While the amorphous samples were not photo-electro-chemically active, the annealed samples revealed significant photocurrent density. Layers prepared by reactive magnetron sputtering exhibited photocurrents comparable to those of the layers prepared by sedimentation process. However, the combined layers achieved photo-currents approximately twice higher than the total sum of photocurrents of separate films prepared by particle deposition and by magnetron sputtering. The combined layer revealed also the best results in electrochemical impedance spectroscopy and achieved the highest efficiency in photocatalytical decomposition of monuron herbicide.