Fabrication study of ultraviolet sensors using surface acoustic wave devices with zinc oxide nanostructures

• Main Authors: Yu-Hao Liu, 劉育豪
• Other Authors: Hui-Ling Kao
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/21267552304106361231

碩士 === 中原大學 === 電子工程研究所 === 104 === In this study, the ultraviolet sensors based on surface acoustic wave (SAW) oscillators using ST-quartz piezoelectric material have been investigated. The network analyzer was employed to measure the ZnO/ST-Quartz SAW devices to obtain the center frequency of 194.4MHz and insertion loss of -20.047dB. The spectrum analyzer measurement shows that the average frequency shift is 1.15 kHz under ultraviolet radiation with power density of 0.5mW/cm2. TCF was obtained to -9ppm/℃ by temperature stability measurement. In this experiments, ZnO/ST-quartz structure successfully decrease the thermal effect of frequency shift. But the sensitivity of device is low under ultraviolet radiation with small power density. To increase the sensitivity, ZnO nanorods structure by chemical bath deposition on ZnO (delay-line) has been employed. The higher surface-to-volume ratio of nanorods structure has enhanced the sensitivity and responsivity of SAW devices. Thus, a UV sensor with high sensitivity and high responsivity was constructed using a simple fabrication process. The photoelectric properties of ZnO nanorods has been verified by the metal-semiconductor-metal (MSM) device. The ratio of photo to dark current of 3 orders of magnitudes was higher than that of ZnO films MSM devices was obtained. The SAW oscillator designed and fabricated with network matching. The spectrum analyzer measurement shows that the center frequency of SAW device is 194.5MHz and the average frequency shift is 12.1 kHz under ultraviolet radiation with power density of 0.5mW/cm2. The obtained sensitivity is 123.3ppm(mW/cm2)-1.