title: Electronic Properties of MoS2-WS2 Heterostructures Synthesized with Two-Step Lateral Epitaxial Strategy.
abstract: Formation of heterojunctions of transition metal dichalcogenides (TMDs) stimulates wide interest in new device physics and technology by tuning optical and electronic properties of TMDs. TMDs heterojunctions are of scientific and technological interest for exploration of next generation flexible electronics. Herein, we report on a two-step epitaxial ambient-pressure CVD technique to construct in-plane MoS2-WS2 heterostructures. The technique has the potential to artificially control the shape and structure of heterostructures or even to be more potentially extendable to growth of TMD superlattice than that of one-step CVD technique. Moreover, the unique MX2 heterostructure with monolayer MoS2 core wrapped by multilayer WS2 is obtained by the technique, which is entirely different from MX2 heterostructures synthesized by existing one-step CVD technique. Transmission electron microscopy, Raman and photoluminescence mapping studies reveal that the obtained heterostructure nanosheets clearly exhibit the modulated structural and optical properties. Electrical transport studies demonstrate that the special MoS2 (monolayer)/WS2 (multilayer) heterojunctions serve as intrinsic lateral p-n diodes and unambiguously show the photovoltaic effect. On the basis of this special heterostructure, depletion-layer width and built-in potential, as well as the built-in electric field distribution, are obtained by KPFM measurement, which are the essential parameters for TMD optoelectronic devices. With further development in future studies, this growth approach is envisaged to bring about a new growth platform for two-dimensional atomic crystals and to create unprecedented architectures therefor.
authors.affiliation: Department of Electronic Engineering and Materials Science and Technology Research Center, The Chinese University of Hong Kong , Hong Kong, SAR P. R. China.
authors.forename: Kun
authors.initials: K
authors.lastname: Chen
authors.affiliation: Department of Electronic Engineering and Materials Science and Technology Research Center, The Chinese University of Hong Kong , Hong Kong, SAR P. R. China.
authors.forename: Xi
authors.initials: X
authors.lastname: Wan
authors.affiliation: State Key Laboratory of Optoelectronic Materials and Technologies and Guangdong Province Key Laboratory of Display Material and Technology, School of Physics and Engineering, Sun Yat-sen University , Guangzhou 510275, China.
authors.forename: Jinxiu
authors.initials: J
authors.lastname: Wen
authors.affiliation: Siyuan Laboratory, Department of Physics, Jinan University , Guangzhou 510632, China.
authors.forename: Weiguang
authors.initials: W
authors.lastname: Xie
authors.affiliation: Department of Electronic Engineering and Materials Science and Technology Research Center, The Chinese University of Hong Kong , Hong Kong, SAR P. R. China.
authors.forename: Zhiwen
authors.initials: Z
authors.lastname: Kang
authors.affiliation: Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences , Shenzhen 518055, China.
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Zeng
authors.affiliation: State Key Laboratory of Optoelectronic Materials and Technologies and Guangdong Province Key Laboratory of Display Material and Technology, School of Physics and Engineering, Sun Yat-sen University , Guangzhou 510275, China.
authors.forename: Huanjun
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Electronic Engineering and Materials Science and Technology Research Center, The Chinese University of Hong Kong , Hong Kong, SAR P. R. China.
authors.forename: Jian-Bin
authors.initials: JB
authors.lastname: Xu
keywords: KPFM; MoS2−WS2 heterostructure; built-in electric field; built-in potential; depletion-layer width; two-step epitaxial CVD method