Rapid response and recovery humidity sensor based on CoTiO3 thin film prepared by RF magnetron co-sputtering with post annealing process

Abstract

The fast-response humidity sensor based on CoTiO3 thin film was prepared by RF magnetron co-sputtering using TiO2 and Co2O3 targets followed by post-annealing process. The effects of annealing temperature and target sputtering power ratio on the preparation and humidity sensing properties of CoTiO3 films were thoroughly investigated. The results show that an annealing treatment is beneficial for the crystallization and (100) preferred orientation of CoTiO3 film. The sputtering power ratio of Co2O3 to TiO2 affects the phase composition and morphology of the films. The most sensitive CoTiO3 film with fastest response/recovery is prepared by employing co-sputtering power of 100W and 400W for Co2O3 and TiO2, respectively, as well as the post-annealing at 650°C for two hours. The sensitivity value of the as-prepared CoTiO3 film is 17.02 towards 95% RH, and the response/recovery time is as short as 1s. This fast response is attributed to (100) preferred orientation and the fine-established-net morphology.