Electrical, Optical and Sensing Properties of Photo-activated ZnO Thin Films

Zinc oxide is a wide gap semiconductor whose chemical activity at surface can be enhanced by proper electromagnetic radiation. This property opens the door to room temperature gas sensing with this material. In this work, nanosized ZnO powder was synthesized by sol-gel technique. Then, structural and morphological characterizations were carried out by means of X-Ray Diffraction and SEM techniques. Thin films were deposited by spin coating technique on both glass and alumina substrates, to perform optical absorption spectra and electrical conductance measurements, respectively. The electro-optical properties were studied on the photo-activated films, in air and in nitrogen conditions, to investigate first on the basic surface-oxygen interaction in photo-activated condition. Then, gas measurements were also performed in air and in nitrogen, to acquire information on the photo-enhanced surface chemistry, in order to be applied to gas sensing.