The study of ZnO/LiNbO3 SAW oscillator and its sensor application

• Main Authors: Jiun-Lin Fu, 傅俊霖
• Other Authors: Kuo-Sheng Kao
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/31421679139663012468

碩士 === 樹德科技大學 === 電腦與通訊研究所 === 96 === Zinc oxide (ZnO) owns the excellent piezoelectricity and therefore is used to be fabricated for the acoustic device. The ZnO film adopted as active layer because of its bandgap of 3.2 eV is also an excellent ultraviolet (UV) absorption material. There are two types of ZnO-based UV detectors, the photoconduction layers type and metal-semiconductor Schottky barrier type. The surface acoustic wave (SAW) oscillator based on ZnO/lithium niobate (LiNbO3) is classified to the photoconduction layers type. The SAW device is composed of LiNbO3 substrate and specific thickness ZnO films. The shifts of resonance frequency with various temperature and UV illumination intensities are observed. On the other side, owing to the high temperature sensitivity, the characteristic of temperature sensing is also evaluated in this study. The ZnO films are deposited using the reactive RF magnetron sputter. The microstructure and crystallization of the ZnO films are investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. In the beginning, the ZnO/LiNbO3 SAW devices are fabricated. In cooperated with high gain amplifier and an impedance match circuit, the oscillators are completed. The frequency responses varied with temperature and UV power are finally measured. For the UV sensing application, the sensitivity of 60 KHz/μW-cm2 is achieved for the ZnO/LiNbO3 SAW oscillator. For the temperature sensing application, the sensitivity of 2MHz/℃ is calculated in the range of room temperature to 50℃.