Properties of tungsten oxide thin films formed by ion-plasma and laser deposition methods for MOSiC-based hydrogen sensors

Thin-film structures based on gas-sensitive tungsten oxide and catalytic platinum are fabricated by room-temperature deposition on a silicon carbide wafer using pulsed laser and ion-plasma methods. Oxide layer annealing in air to 600$^\circ$C caused the formation of microstructured and nanostructured crystalline states depending on the deposition conditions. Structural differences affect the electrical parameters and the stability of characteristics. The maximum response to hydrogen is detected in the structure fabricated by depositing a low-energy laser-induced flow of tungsten atoms in oxygen. The voltage shift of the currentvoltage curves for 2% H$_2$ in air at 350$^\circ$C was 4.6 V at a current of $\sim$10 $\mu$A. The grown structures’ metastability caused a significant decrease in the shift after long-term cyclic testing. The most stable shifts of $\sim$2 V at positive bias on the Pt contact were detected for oxide films deposited by ion-plasma sputtering.