Noise Properties of ZnO Nanowalls Deposited Using Rapid Thermal Evaporation Technology

ZnO nanowalls are rapidly grown on a glass substrate using a low-temperature thermal evaporation method, without the use of a catalyst and the pre-deposition of a ZnO seed layer on the substrate. Most of the ZnO nanowalls are grown vertically and are about 70-200-nm thick and 2-μm long. The room-temperature photoluminescence spectra show a strong intrinsic ultraviolet (UV) emission and a weak defect-related orange emission. The ZnO nanowall UV sensor is highly sensitive to UV light, with an excellent UV-to-visible ratio and good flicker noise characteristics. This shows the strong potential of ZnO nanowalls for use in UV sensors. At an applied bias of 2 V, the noise equivalent power and the normalized detectivity of the ZnO nanowall UV sensor are 1.87 × 10^-10 W and 3.38 × 10⁹ cm·Hz^0.5·W^-1, respectively.