Three-dimensional ZnO hybrid nanostructures for oxygen sensing application

Three-dimensional (3D) ZnO hybrid nanostructures, composed of a bottom ZnO film, ZnO nanowire arrays, and a top ZnO film, are continuously fabricated by adjusting the supersaturation conditions, using metal-organic chemical vapour deposition, to utilize the vertically aligned ZnO nanowires as an active element in oxygen sensing applications. The oxygen sensing characteristics of the different 3D hybrid nanostructures, fabricated to have different average values of radius and length of the ZnO nanowire arrays, are studied comparatively without complicated nanowire manipulation processes. The decrease of the current flow through the ZnO nanowire arrays with increasing ambient oxygen concentration indicates that the 3D hybrid nanostructures can be applied in oxygen sensors. In addition, the 3D hybrid nanostructure having thinner radius of the nanowire arrays exhibits higher oxygen sensitivity.