Influence of structural orientation of tungsten oxide films on gas sensing properties

Tungsten oxide films with different preferred orientations were deposited by reactive magnetron sputtering with glancing angle deposition. The influence of the structural orientation of the films on the NO2 gas sensing properties was investigated through orthogonal experiments. The film deposited at a lower Ar/O2 ratio and higher sputtering pressure displayed a significantly enhanced NO2 sensing performance, which can be attributed to the high crystallinity and (200)-preferred orientation of monoclinic WO3. There are more active sites near the surface of the (200)-oriented WO3 films, which is beneficial for NO2 adsorption, enhancing the gas sensing properties. Clarifying the effect of structural orientation on the gas response will guide further optimization of sensing films, aiding the fabrication of high-performance MEMS gas sensors.