title: Gate tunable WSe2-BP van der Waals heterojunction devices.
abstract: Due to the weak screening effect, the concentration and type of charge carriers in 2D semiconductor heterostructures can be effectively tuned by electrostatic gating, enabling us to realize different types of heterojunctions in a single device. Such 'type tunable' properties are useful for designing novel electrical or optoelectrical devices. Here, we demonstrate a 'type tunable' heterojunction device construct with two pieces of ambipolar 2D semiconductors: WSe2 and black phosphorus (BP). This heterojunction could be tuned to either the p-p junction or n-n junction by gate modulation. The p-p junction shows a large current rectification ratio while the n-n junction shows a negligible current rectification ratio, indicating a large valence band offset and a small conduction band offset at the WSe2/BP interface. In the optoelectrical measurements, we found the amplitude and even the polarity of photocurrent could be modulated by electrostatic gating. Our study could further enhance the understanding of designing devices based on these 'type tunable' van der Waals heterojunctions. Moreover, the properties of the WSe2/BP interface were also experimentally identified through the electrical and optoelectrical measurements in our study.
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Chen
authors.forename: Ting Ting
authors.initials: TT
authors.lastname: Zhang
authors.forename: Jing
authors.initials: J
authors.lastname: zhang
authors.forename: Jianyong
authors.initials: J
authors.lastname: Xiang
authors.forename: Hua
authors.initials: H
authors.lastname: Yu
authors.forename: Shuang
authors.initials: S
authors.lastname: Wu
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Lu
authors.forename: Guole
authors.initials: G
authors.lastname: Wang
authors.forename: Fusheng
authors.initials: F
authors.lastname: Wen
authors.forename: Zhongyuan
authors.initials: Z
authors.lastname: Liu
authors.forename: Rong
authors.initials: R
authors.lastname: Yang
authors.forename: Dongxia
authors.initials: D
authors.lastname: Shi
authors.forename: Guangyu
authors.initials: G
authors.lastname: Zhang