High quality ZnO film prepared on ITO substrate for H2 sensing application

In this paper, we report the temperature effect on the properties of ZnO films prepared on ITO coated glass substrate by a spray pyrolysis technique. XRD studies revealed the polycrystalline hexagonal wurtzite ZnO structure. The promoting effect of ITO on the crystal quality of ZnO film is reflected in the film prepared at 350 degrees C. The red-shift in the PL peak with increase in temperature was confirmed from the decrease in the optical band gap of the film, contributed partially by the size effect and partially by the strain relaxation of ZnO crystallites. Highly compact and porous morphology of the films with large RMS roughness favored the surface reactivity with H-2 gas. The large response of ZnO/ITO sensor at low operating temperature, with fast response and recovery was attributed to the microstructure of the ITO underlayer. (C) 2015 Elsevier B.V. All rights reserved.