Analysis of the Impact of Heat Treatment and the Presence of Hydrogen on the Optical Properties of WO3 Thin Films Prepared by EBE

The paper presents the results of a study of the optical and gasochromic properties of WO 3 thin films fabricated by electron beam evaporation. After deposition, the films were heated at 800 °C and then a Pd layer was deposited to the surface. Structural studies showed that after annealing, the structure of the coating changed from amorphous to crystalline The study of optical properties was performed by analyzing refractive index spectra. It was found that annealing causes an increase in refractive index values. The annealed layers were then subjected to a study of gasochromic properties in the presence of 25 ppm hydrogen. From the recorded transmission spectra, the refractive index waveforms were determined and a significant increase in this parameter was found, most likely due to the reduction of WO 3 to WO 2 . The study shows that thermal treatment significantly affects film morphology, optical transmission and hydrogen sensitivity, confirming the potential of WO 3 in optical gas detection applications.