Improving the hydrogen gas sensitivity of WO3 thin films by modifying the deposition angle and thickness of different promoter layers

In this research, we tried to improve the H2 gas sensitivity of WO3 thin films by changing the deposition angle and thickness of different promoter layers (Pt and Au). The WO3 thin films of 100 nm thickness were deposited by e-beam evaporation technique on SiO2/Si substrates and then post-annealed at 500 °C with a flow of oxygen for 4 h. Two various promoter layers (Pt and Au) were deposited on the WO3 thin films by e-beam evaporation method under different thicknesses (3, 6, and 9 nm) and deposition angles (0 and 30 deg.). The sensitivity of all activated and non-activated WO3 thin films was tested to 0.1% hydrogen gas at different temperatures (40-240 °C). The investigations show that the hydrogen gas sensitivity of the samples is improved by an increase in the Pt layer thickness and oblique deposition of the Au layer. The results also show that the WO3 thin films activated with Pt layer present more reliability than the sample activated with Au layer.