UV-activated SnO2 thin film for air-atmospheric oxygen sensing at room temperature

A semiconductor oxygen sensor based on UV-activated SnO2 thin film, which can detect oxygen in air-atmospheric with good selectivity and stability (sensitivity variation was less than 3.3% during 62 days), was fabricated by a two-step method (i.e., sputtering deposition and following thermal oxidation of Sn-film). In comparison with traditional one-step method (directly reactive sputtering of SnO2 film), the SnO2 film fabricated by the two-step method has much higher crystallinity, faster response speed and better selectivity. A detection limit of 1% oxygen concentration was realized, and the effects of wavelength and intensity of UV activation on sensing performance were investigated. To our knowledge, it is the first demonstration that semiconductor metal oxide oxygen sensor can operate in air-atmosphere at room temperature. •For first time metal-oxide O2 sensor operates in air-atmosphere at room temperature.•Sensor fabricated by two-step method shows higher selectivity and faster speed.•Wavelength 20 mW/cm2 is optimum for UV activation.