Tungsten oxide nanowire sensors grown by cold wall reactor aerosol assisted chemical vapour deposition

This paper reports on a new method for the growth of single-crystalline WO₃ nanoneedles (NN) on sensor substrates using a horizontal aerosol assisted CVD cold wall reactor. The heating element of the sensors is used to keep the appropriate growth temperature. The morphology and the crystalline structure of the films were characterized by using scanning electron microscopy, X-ray diffraction and Raman spectroscopy, and the results proved the synthesis of thin layers of monoclinic WO₃ NN with preferred orientation in the [002] direction. The gas sensing properties of the films were also evaluated by exposing our sensors to different analytes: EtOH, H₂, and CO and we have compared their responses to those obtained from WO₃ sensors fabricated by a hot AA-CVD wall reactor. The new growth method is able to highly improve sensor stability and sensitivity in comparison to the conventional hot wall reactor. Additionally, it could be more easily adapted to rigid and flexible sensor substrates.