Metal-semiconductor-metal (MSM) ultraviolet (UV) photodetectors with ZnO nanorods (NRs) have been fabricated and characterized in this investigation. The NR arrays were selectively grown on the gap of interdigitated electrodes by chemical solution method through a photolithography process. Compared to a traditional ZnO MSM photodetector with no NRs, the fabricated NR UV photodetector showed much higher photoresponsity. As a result, it can be attributed to high surface-to-volume ratio of ZnO NRs and such a high photoresponse could strongly depend on oxygen adsorption/desorption process in the presence of trap states at the NR surface.

An ultraviolet-enhanced (UV-enhanced) nitric oxide (NO) sensor based on silver-doped zinc oxide (ZnO) nanoflowers is developed using a low-cost hydrothermal method. The results indicate that silver (Ag) ions were doped into the ZnO nanostructure successfully, thus changing the morphology. In the high-resolution transmission electron microscopy images, we also found that some Ag ions were separated out onto the surface of the ZnO nanoflowers and that the Ag-doped and Ag nanoparticles improved the sensing property. The NO sensing property increased from 73.91 to 89.04% through the use of a UV light-emitting diode (UV-LED). The response time was approximately 120 s without the UV-LED, and the UV-enhanced Ag-doped ZnO nanoflower sensor exhibited a reduced response time (60 s). The best working temperature could be reduced from 200 to 150 °C using UV light illumination, and it was found that the NO response increased by 15.13% at 150 °C. The UV photoresponse of the Ag-doped ZnO nanoflowers and the mechanisms by which the improvement of NO sensing property occurred through the use of UV light illumination are discussed. The property of the gas sensor can be calibrated using a self-photoelectric effect under UV light illumination. These interesting UV-enhanced Ag-doped ZnO nanoflowers are viable candidates for practical applications.