Current Applied Physics, Vol.20, No.7, 904-910, 2020
Evaluation of acoustoelectric UV sensor according to ZnO thin film properties
This paper presents an improvement of the acoustoelectric effect by sensitivity and response of ultraviolet (UV) sensors by changing the argon/oxygen ratio. The acoustoelectric sensor is a delay-line type with a center frequency of 240.2625 MHz and fabricated on a piezoelectric substrate. Aluminum thin films were deposited as interdigitated transducers and patterned, and the ZnO thin film was deposited as a UV sensing layer by controlling the ratio of argon and oxygen with an RF magnetron sputtering. By increasing the oxygen partial pressure during ZnO deposition, the photoconductivity increased by 6.5 times, thereby increasing the frequency change related to the sensitivity of the sensor. The sensitivity to UV light was 110.4 Hz cm(2)/mu W under an argon/ oxygen ratio of 6:4, which is an increase of 5.1 times from 21.76 Hz cm(2)/mu W obtained under a ratio of 10:2. In addition, the response and recovery times were improved by 2.85 times and 3.02 times, respectively.