title: Zener Tunneling and Photoresponse of a WS2/Si van der Waals Heterojunction.
abstract: Van der Waals heterostructures built from two-dimensional materials on a conventional semiconductor offer novel electronic and optoelectronic properties for next-generation information devices. Here we report that by simply stacking a vapor-phase-synthesized multilayer n-type WS2 film onto a p-type Si substrate, a high-responsivity Zener photodiode can be achieved. We find that above a small reverse threshold voltage of 0.5 V, the fabricated heterojunction exhibits Zener tunneling behavior which was confirmed by its negative temperature coefficient of the breakdown voltage. The WS2/Si heterojunction working in the Zener breakdown regime shows a stable and linear photoresponse, a broadband photoresponse ranging from 340 to 1100 nm with a maximum photoresponsivity of 5.7 A/W at 660 nm and a fast response speed of 670 μs. Such high performance can be attributed to the ultrathin depletion layer involved in the WS2/Si p-n junction, on which a strong electric field can be created even with a small reverse voltage and thereby enabling an efficient separation of the photogenerated electron-hole pairs.
authors.affiliation: State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China , Chengdu 610054, China.
authors.forename: Changyong
authors.initials: C
authors.lastname: Lan
authors.affiliation: State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China , Chengdu 610054, China.
authors.forename: Chun
authors.initials: C
authors.lastname: Li
authors.affiliation: State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China , Chengdu 610054, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China , Chengdu 610054, China.
authors.forename: Tianying
authors.initials: T
authors.lastname: He
authors.affiliation: Chongqing Key Laboratory of Multi-scale Manufacturing Technology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences , Chongqing 400714, China.
authors.forename: Tianpeng
authors.initials: T
authors.lastname: Jiao
authors.affiliation: Chongqing Key Laboratory of Multi-scale Manufacturing Technology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences , Chongqing 400714, China.
authors.forename: Dapeng
authors.initials: D
authors.lastname: Wei
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology , Wuhan 430074, China.
authors.forename: Wenkui
authors.initials: W
authors.lastname: Jing
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology , Wuhan 430074, China.
authors.forename: Luying
authors.initials: L
authors.lastname: Li
authors.affiliation: State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China , Chengdu 610054, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Liu
keywords: 2D crystals; WS2; Zener diode; photodetector; van der Waals heterostructures