Annealing effects on the structural, electrical and H2 sensing properties of transparent ZnO thin films, grown by pulsed laser deposition

Transparent zinc oxide thin films were grown by reactive pulsed laser deposition on glass substrates. The substrates were kept at 200 oC constant temperature. Post-deposition heat treatment, applied to further promote crystallization and overcome any oxygen deficiency, yielded transparent thin films. Structural investigations carried out by atomic force microscopy (AFM) and X-ray diffraction (XRD), have shown a strong influence of deposition technique parameters and post-annealing on the crystallinity of the zinc oxide films. The gas sensing characteristics of these films were investigated towards different hydrogen concentrations (5000-30,000 ppm) at a selected operating temperature within the 150-230 oC range.