Vertical Ti doped ZnO nanorods based on ethanol gas sensor prepared on glass by furnace system with hotwire assistance

High density vertical Ti doped ZnO (ZnO:Ti) nanorods (NRs) were uniformly grown on ZnO/glass substrate at 600 °C by a furnace system with Ti hotwire assistance. The Ti dopant concentrations are 0.87% and 1.86 at.%. The XRD and HRTEM images of ZnO:Ti NRs revealed a wurtzite structure oriented in the c-axis direction. The XRD (0 0 2) peaks of the 0.87% and 1.86% Ti-containing samples are shifted to a smaller angle by approximately 0.04° and 0.23°, respectively. That photoluminescence (PL) dominated indicates that the increasing Ti dopant has a great amount of oxygen vacancies by observed green band increasing. The UV band of the PL spectra was blue shifted and increased with increasing Ti. The TEM–EDX mapping images reveal that the majority of Ti atoms are located at the top of the ZnO:Ti NRs. The conductivity of 1.86% Ti-containing samples was 80.7 times higher than the pure ZnO NRs. The ethanol gas responses of the ZnO:Ti NR sensor were around 27.5%, 66.7%, 117.1%, 183.5%, 276.5% and 389.5% when the ethanol gas concentration was 10, 50, 100, 250, 500 and 1000 ppm, respectively. The ethanol gas responses of the ZnO:Ti NRs are higher than that of the ZnO NRs by around 5.1 times at ethanol 1000 ppm concentration.