In2O3 AND WO3-DOPED In2O3 HYDROTHERMALLY SYNTHETIZED AS PROMISING OZONE SENSITIVE MATERIALS

This work deals with MOS (metal oxide semiconductors) ozone sensors based on n-type In2O3 and 2.5 wt.% WO3-doped In2O3thick film to monitor O3 at sub-ppm level and at low temperatures. In2O3was synthetized by three different methods, with the aim to decrease the crystallite size and enhance the sensor response towards ozone. Among the differently synthesized powders, pristine In2O3 produced by hydrothermal route (HT) constitutes a valuable platform for the development of O3 detectors, improving the sensor performances compared to the commercial In2O3 (SA). In this work, HT- In2O3 was doped with WO3 by an impregnation route to enhance its sensitivity towards ozone. Powders were characterized by laser granulometry, X-Ray Diffraction, Field Emission Scanning Electron Microscopy, N2 adsorption and X-Ray Photoelectron Spectroscopy. The optimized hydrothermal route allowed to decrease the average crystallite size, since it was around 26 nm for HT-powder and 48 nm for SA-powder. The cross-sensitivity under humidity, NO2, N2O, NH3, CH4 and CO2 was also investigated and doping with WO3 by impregnation route increase the sensitivity towards ozone decreasing the cross-sensitivity under humidity and nitrogen dioxide.