Yttrium - Substituted SnO2 thin films and its gas sensing activity against NH3 gas: Characterization and sensitivity evaluation

Pure and yttrium-doped tin oxide (SnO2:Y) thin film was successfully coated on a glass substrate using a nebulizer spray pyrolysis technique with a constant temperature of 400 degrees C. Coated films are characterized by a variety of techniques like XRD, SEM with EDX, TEM, elemental mapping, UV, PL, and gas sensors. All XRD film patterns demonstrate a well-defined polycrystalline phase, which fits well with the SnO2 tetragonal rutile structure. Surface morphology analysis revealed that the surface roughness of the SnO2:Y thin films increased with an increase in yttrium concentration. Transmission Electron Microscopy and SAED findings result suggested that the SnO2:Y thin films were highly crystalline. The optical band gap (3.66 eV -3.81 eV) rises due to Y- doping points the credibility of SnO2 thin films. Photoluminescence (PL) spectroscopy revealed a large number of oxygen vacancies in SnO2:Y films. The PL intensity varies with the doping concentrations. The gas sensing capability of nanostructured films was compared to the concentration of Y-doping and NH3 concentrations from 25 ppm to 125 ppm. For the SnO2:Y(5 wt.%) film, a significant response with short response time and recovery time (23 s, 7 s) to 25 ppm NH3 is observed at room temperature. The yttrium loaded SnO2 sensor is indeed a promising candidate for NH3 detection. (C) 2020 Elsevier B.V. All rights reserved.