Highly sensitive ultraviolet sensor based on ZnO nanorod film deposited on ST-cut quartz surface acoustic wave devices

A highly sensitive surface acoustic wave (SAW) ultraviolet (UV) detector operated at room temperature was developed using a sensing layer of zinc oxide (ZnO) nanorods (NRs) grown on ST-cut quartz using a hydrothermal method. Under illumination of the UV light with a wavelength of 365 nm and an intensity of 6 μW cm−2, the resonant frequency of the SAW UV sensor based on ZnO NRs/ZnO nanofilm structure was decreased by ~200 Hz, mainly due to electroacoustic effect. The estimated enhancement in the sensitivity based on the experimental results is ~3.5 folds compared to a device with only a thin nanolayer ZnO film. Meanwhile, density of ZnO NRs over the ZnO seed layer was also investigated and an optimum design was proposed.