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

Abstract A SnO 2 :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 SnO 2 , 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 SnO 2 :Sn/Si-NPA and its room-temperature humidity-sensing properties were studied at 25 °C. The SnO 2 :Sn/Si-NPA sensor prepared with an oxidation time of 30 min shows superior humidity-sensing properties. A humidity response over 265% was obtained in the relative humidity (RH) range of 11–95% at 1 kHz. The response and recovery times were determined to be ∼20 s 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 SnO 2 :Sn/Si-NPA might be a promising candidate for fabricating practical humidity sensor.