title: UV sensing using film bulk acoustic resonators based on Au/n-ZnO/piezoelectric-ZnO/Al structure.
abstract: A new type of ultraviolet (UV) light sensor based on film bulk acoustic wave resonator (FBAR) is proposed. The new sensor uses gold and a thin n-type ZnO layer deposited on the top of piezoelectric layer of FBAR to form a Schottky barrier. The Schottky barrier's capacitance can be changed with UV light, resulting in an enhanced shift in the entire FBAR's resonant frequency. The fabricated UV sensor has a 50 nm thick n-ZnO semiconductor layer with a carrier concentration of ~ 10(17) cm(-3). A large frequency downshift is observed when UV light irradiates the FBAR. With 365 nm UV light of intensity 1.7 mW/cm(2), the FBAR with n-ZnO/Au Schottky diode has 250 kHz frequency downshift, much larger than the 60 kHz frequency downshift in a conventional FBAR without the n-ZnO layer. The shift in the new FBAR's resonant frequency is due to the junction formed between Au and n-ZnO semiconductor and its properties changes with UV light. The experimental results are in agreement with the theoretical analysis using an equivalent circuit model of the new FBAR structure.
authors.affiliation: Dept. of Info. Sci. &Electr. Eng., Zhejiang University and Cyrus Tang Center for Sensor Materials and Applications, 38 Zheda Road, Hangzhou 310027, China.
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Bian
authors.affiliation: Dept. of Info. Sci. &Electr. Eng., Zhejiang University and Cyrus Tang Center for Sensor Materials and Applications, 38 Zheda Road, Hangzhou 310027, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Jin
authors.affiliation: Dept. of Info. Sci. &Electr. Eng., Zhejiang University and Cyrus Tang Center for Sensor Materials and Applications, 38 Zheda Road, Hangzhou 310027, China.
authors.forename: Xiaozhi
authors.initials: X
authors.lastname: Wang
authors.affiliation: Dept. of Info. Sci. &Electr. Eng., Zhejiang University and Cyrus Tang Center for Sensor Materials and Applications, 38 Zheda Road, Hangzhou 310027, China.
authors.forename: Shurong
authors.initials: S
authors.lastname: Dong
authors.affiliation: Dept. of Info. Sci. &Electr. Eng., Zhejiang University and Cyrus Tang Center for Sensor Materials and Applications, 38 Zheda Road, Hangzhou 310027, China.
authors.forename: Guohao
authors.initials: G
authors.lastname: Chen
authors.affiliation: 1] Dept. of Info. Sci. &Electr. Eng., Zhejiang University and Cyrus Tang Center for Sensor Materials and Applications, 38 Zheda Road, Hangzhou 310027, China [2] Institute of Renewable Energy &Environ. Technol., Univ of Bolton, Bolton, BL3 5AB, UK.
authors.forename: J K
authors.initials: JK
authors.lastname: Luo
authors.affiliation: 1] Dept. of Info. Sci. &Electr. Eng., Zhejiang University and Cyrus Tang Center for Sensor Materials and Applications, 38 Zheda Road, Hangzhou 310027, China [2] Electrical and Computer Engineering, McMaster University, Hamilton, ON L8S 4K1, Canada and ECE Department, Hong Kong University of Science and Technology, Kowloon, Hong Kong.
authors.forename: M Jamal
authors.initials: MJ
authors.lastname: Deen
authors.affiliation: College of Internet of Things Engineering, Hohai University, Changzhou, 213022, China.
authors.forename: Bensheng
authors.initials: B
authors.lastname: Qi