IGZO-decorated ZnO thin films and their application for gas sensing

In this study, indium-gallium-zinc oxide (IGZO)-decorated ZnO thin films were investigated through the change in IGZO deposition time for the detection of NO₂ gas. The atomic layer deposited ZnO on interdigitated Au electrode alumina substrates are decorated with IGZO by controlling the deposition time. The IGZO (ZnO:Ga₂O₃:In₂O₃ = 1:1:1 mol. %) polycrystalline target was used for deposition and effect of deposition time was investigated. The sensor responses (R_gas/R_air) of 20.6, 39.3, and 57.1 and 45.2, 102.5, and 243.5 were obtained at 150 °C, 200 °C, and 250 °C and 25-ppm NO₂ concentration for ZnO (Z1) and IGZO-decorated ZnO (Z3) films, respectively. The sensor response (R_gas/R_air) increased from ∼27 to 243.5 by decorating the ZnO film with IGZO for a 60-s sputtering time. The sensor recovery and response times of the IGZO-decorated ZnO/ZnO sensor increased, and the sensor selectivity to different gases was also evaluated.