Effect of Fe modification on H2S sensing properties of rheotaxially grown and thermally oxidized SnO2 thin films

Abstract Gas sensing properties of pure and Fe modified SnO 2 thin films deposited by rheotaxialgrown and thermal oxidation (RGTO) method have been investigated. Modification of SnO 2 surface with Fe results in an improved and selective response towards H 2 S. Sensor films containing 0.64 at % Fe exhibited a sensor response of 14.5 towards 10 ppm of H 2 S at 225 °C with a response and recovery time of 90 and 98 s, respectively. Long term stability measurements indicate that the sensor response is stable over a measured period of 35 days. X-ray photoelectron spectroscopyanalysis indicates that Fe exists in the form of Fe 3 O 4 over the SnO 2 sensor surface. An improved response towards H 2 S is attributed to the formation of low band gap FeS upon interaction of Fe 3 O 4 with the H 2 S. A gas sensing mechanism has been proposed using the results of sensing characteristics, x-ray photoelectron spectroscopyand work function measurements.