Preparation of high-aspect-ratio ZnO nanorod arrays by chemical bath deposition and its application to chemical sensors for organic solvents

• Main Authors: Min-Ren Zheng, 鄭閔仁
• Other Authors: Yi-Mu Lee
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/26806030284106747066

碩士 === 國立聯合大學 === 電子工程學系碩士班 === 101 === N-type ZnO nanorod arrays has been prepared on the ITO substrates by low-temperature chemical bath deposition (CBD) combined with heat treatment at 400 °C for 1h. The structural properties of the prepared ZnO nanostructures were analyzed by X-ray diffraction (XRD), SEM and energy-dispersive X-ray spectroscopy (EDS). From the SEM images, it is clearly seen that the ZnO nanostructures exhibit a hexagonal phase and excellent c-axis orientation along the substrate. The highly oriented nanorod arrays have average length of 3.4 μm and average diameter of 110 nm, leading to high-aspect ratio value of 30.9. For room-temperature sensing experiment, a simple two-electrode electrochemical system with electrical impedance measurement has been constructed. In the first, the ZnO-based sensors are employed for the detection of liquid ethanol with concentration range from 0.1~99.5% (v/v). Nyquist curves reveal a very low series resistance and smooth semicircle, suggesting that our measurement setup is an efficient sensing system for aqueous solution systems. In the second, we focus on the detection of different organic solutions, methanol, ethanol, isopropyl alcohol and acetone, under very low concentration (0~1%, v/v). The sensing properties such as impedance change, relaxation time, dielectric constant, sensitivity and stability have been investigated. Furthermore, the effects of ZnO nanorod length and aspect-ratio on the sensing performance are discussed according to the Nyquist plots and the dielectric properties. Keywords: ZnO nanord arrays, CBD, liquid sensing, impedance measurements, stability test.