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

Abstract

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 NO 2 gas sensing properties was investigated through orthogonal experiments. The film deposited at a lower Ar/O 2 ratio and higher sputtering pressure displayed a significantly enhanced NO 2 sensing performance, which can be attributed to the high crystallinity and (200)-preferred orientation of monoclinic WO 3 . There are more active sites near the surface of the (200)-oriented WO 3 films, which is beneficial for NO 2 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. • WO 3 films with different degrees of preferred orientation were deposited by glancing angle deposition. • The WO 3 film with higher crystallinity and stronger (200)-preferred orientation displayed significantly enhanced response to NO 2 . • The improvement of sensing performance can be mainly attributed to more active sites for NO 2 adsorption near the surface of (200)-oriented monoclinic WO 3 . • The effect of structural orientation on gas response of WO 3 films can be used as a reference for further optimization of sensing films.