TiO 2-ZnO Composite thin films fabricated by Sol-Gel spin coating for room temperature impedometric acetone sensing

Metal oxide semiconductor based volatile organic compounds (VOCs) sensors lack room temperature operation and have a poor limit of detection. In this work, TiO2-ZnO composite thin film based acetone sensors with room temperature (29 +/- 2 degrees C) operation and good sensor response have been fabricated by sol-gel based spin coating. The thin films based on the single-phase TiO2 and ZnO together with their composites have been evaluated for their structural and surface morphological properties through X-ray diffraction and field emission scanning electron microscopy respectively. The surface chemical state of the thin films surface has been analyzed through the X-ray photoelectron spectroscopy. The optical properties of the single-phase as well as the composite phase thin films were studied by optical absorption spectroscopy. The acetone sensing characteristics of these thin films based sensors were evaluated through impedance spectroscopy. The composite thin films were found to exhibit the maximum sensor response of 93.83% with a detection threshold of 3 ppm for acetone.