SHIH-HUNG LIN2026-10-162026-10-162023-01-01Pure ID: 15346458Pure UUID: 2fdb8f45-798a-469b-9873-36d020d559d810.1109/NANO58406.2023.10231276https://www.scopus.com/pages/publications/85173596025https://scholars.csmu.edu.tw/handle/123456789/31197A surface acoustic wave (SAW) humidity sensor which utilizes ZnO nanorods on top of AlN/c-plane sapphire aims to achieve high sensitivity. The nanorod's morphology, aspect ratio (L/W), and vertical directivity could be controlled by adjusting the concentration of solutions during the hydrothermal process. With a concentration of 0.003 moles, the ZnO nanorods exhibited relatively low rod density and uniform rod-height with highly vertical-alignment. By incorporating such ZnO nanorods on AlN SAW, the sensitivity of the humidity sensor reaches 3.77 kHz/RH% at a relative humidity level of 90 %RH. The ZnO nanorods structure provides a 2.43 times improvement in sensitivity. Additionally, with the ZnO nanorods, the AlN SAW humidity sensor exhibits a fast recovery, which recovery time reduced to 46% of the one without nanorods.6enjournal article