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.