Capacitive humidity sensitivity of SnO2:Sn thin film grown on silicon nanoporous pillar array

Abstract

A SnO2:Sn composite thin film was grown on silicon nanoporous pillar array (Si-NPA) by a vapor–liquid–solid growth method. The main phase of the film is rutile SnO2, with the amount of Sn can be changed through controlling the oxidation time. A capacitive humidity sensor was fabricated through sputtering coplanar interdigital silver electrodes onto SnO2:Sn/Si-NPA and its room-temperature humidity-sensing properties were studied at 25°C. The SnO2:Sn/Si-NPA sensor prepared with an oxidation time of 30min shows superior humidity-sensing properties. A humidity response over 265% was obtained in the relative humidity (RH) range of 11–95% at 1kHz. The response and recovery times were determined to be ∼20s and the maximum hysteresis was ∼2% at 75% RH. The sensor shows high measurement reproducibility, long-term stability and good selectivity. These results indicated that SnO2:Sn/Si-NPA might be a promising candidate for fabricating practical humidity sensor.