Zinc-oxide nanorod array fabricated by high temperature hydrothermal method applied to gas sensor

Zinc oxide (ZnO) nanorod based gas sensor was successfully fabricated with interdigital electrode on silicon substrate. The highest sensitivity value is 5.24 at 600 ppm CO₂ gas ambient. The influence of growth temperature of ZnO ranging from 90 to 190 °C by the high temperature hydrothermal method was investigated. The ZnO nanorod array were characterized by using field emission scanning electron microscopy (FE-SEM), photoluminescence spectroscopy, X-ray diffraction pattern. From FE-SEM results, the morphology of ZnO nanorods changes from hexagonal structure to sponge-like shape as the growth temperature increases. When the growth temperature is below 150 °C, hexagonal nanorod growth is observed. On the other hand, when the growth temperature is above 170 °C sheet growth is found. In the gas sensor measurements, it is found that ZnO nanorod grown at 150 °C has the best gas sensing performance due to its least intrinsic defects in this study.