Structure and NH3 sensing properties of SnO thin film deposited by RF magnetron sputtering

•SnO gas sensors were fabricated by RF magnetron sputtering.•A thin layer of SnO2 was found on the surface of the SnO thin film.•The electrical properties of the sensor were recorded during heat treatment.•NH3 sensing properties of the SnO sensor were examined.•The sensing mechanism of the device was proposed and explained. SnO thin films, 100nm in thickness, were deposited on glass substrates by RF magnetron sputtering. A structure of SnO2/SnO, where few nanometers of SnO2 were determined on the SnO thin film by X-ray photoelectron spectroscopy. In addition, XPS depth profile analysis of the pristine and heat treated thin films was introduced. The electrical behavior of the as-sputtered films during heat treatment in air and nitrogen was recorded to investigate the working conditions for the SnO sensor. Subsequently, the NH3 sensing properties of the SnO sensor at operating temperatures of 50–200°C were examined, in which the p-type semiconducting sensing properties of the thin film were noted. The sensor shows good sensitivity and repeatability to NH3 vapor. Finally, a sensing mechanism was proposed and discussed.