CO sensing properties of TiO2-doped Nb2O5 thin film gas sensor by rf co-sputtering

Abstract

We investigate CO gas sensing properties of TiO2-doped Nb2O5 thin film gas sensors fabricated by rf sputtering from multi-targets. By reasons of thermally instability and low resistance as Nb2O5 thin film gas sensor, the films were deposited from a TiO2- Nb2O5 target in an rf argon plasma. The deposited films were annealed in air at 500 ℃ for 1 h to grow TiO2-Nb2O5 nanocrystals. The annealed films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and I-V curve. The sensitivity of the thin films to 50 ppm of CO gas was tested as a function of temperature from 200 ℃ to 400 ℃. As a result, these thin films obtained high sensitivity and response time of TiO2 films were much higher than Nb2O5 thin film. Moreover, we confirmed that the additives of TiO2 as a sensor material could be improved by doping as CO sensor.