Tzu-Hao Kuo’s research while affiliated with National University of Formosa and other places

In this investigation, gas sensors based on zinc oxide (ZnO) nanorods (NRs) with Co concentration were successfully fabricated and explored. A 100 nm-thick ZnO film was deposited as a seed layer onto Corning glass substrate via radio frequency (RF) magnetron sputtering technique. Then, Co-doped ZnO (CZO) NR arrays were grown by using a simple chemical bath deposition (CBD) method at 95 °C for 3 h and annealing at 450 °C, in which the Co-doping contents are 0, 5, and 10 mM. The surface-tovolume ratio of CZO NRs was higher than that of the pure ZnO structure. X-ray diffraction (XRD) results showed that the synthesised NRs were a single crystalline of the hexagonal wurtzite structure with uniform growth orientation of the c-axis. In addition, increasing ethanol (C2H5OH) response depends on O vacancy (VO) adsorption, which is measured via photoluminescence (PL) emission. Compared with pure ZnO NRs, the results showed that the CZO-5 (with 5 mM Co solution) NRs exhibited a superior sensitivity in C2H5OH gas applications and a fast response/recovery time. Meanwhile, the CZO-5 gas sensor presented a high response rate of 90.71% at 300 °C operating temperature when the concentration of ambient C2H5OH gas was 100 ppm.