Features of formation of metal oxide thin film layers in a gas-sensor structure Pt/WO x /SiC by means of pulsed laser deposition

Abstract

The effect of regimes of reactive pulsed laser deposition (PLD) of WOx thin films on gas sensing performance of a metal-oxide-silicon carbide device potentially applicable for monitoring explosive gases, in particular, hydrogen, and environmentally harmful gases at elevated temperatures was investigated. The films were deposited from a tungsten target in oxygen at room temperature and subjected to high-temperature annealing. The features of the film deposition under free laser plume expansion and the deposition of the plume scattered in a buffer gas were considered. Weak differences in the structural and chemical state of the WOx films arising from the variation of the deposition conditions had a significant influence on the properties of the sensor. Deposition of WOx by the scattered plume at an oxygen pressure of ∼10 Pa made it possible to increase the value of the sensor response to hydrogen at temperatures of 150 to 500°C by more than one order of magnitude. Mathematical modeling of the dynamics of the laser plume expansion from the W target at a given oxygen pressure allowed identifying the factors that have significant influence on the properties of metal oxide films fabricated using various schemes of PLD.