title: Synthesis of WS2xSe2-2x Alloy Nanosheets with Composition-Tunable Electronic Properties.
abstract: Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have recently emerged as a new class of atomically thin semiconductors for diverse electronic, optoelectronic, and valleytronic applications. To explore the full potential of these 2D semiconductors requires a precise control of their band gap and electronic properties, which represents a significant challenge in 2D material systems. Here we demonstrate a systematic control of the electronic properties of 2D-TMDs by creating mixed alloys of the intrinsically p-type WSe2 and intrinsically n-type WS2 with variable alloy compositions. We show that a series of WS2xSe2-2x alloy nanosheets can be synthesized with fully tunable chemical compositions and optical properties. Electrical transport studies using back-gated field effect transistors demonstrate that charge carrier types and threshold voltages of the alloy nanosheet transistors can be systematically tuned by adjusting the alloy composition. A highly p-type behavior is observed in selenium-rich alloy, which gradually shifts to lightly p-type, and then switches to lightly n-type characteristics with the increasing sulfur atomic ratio, and eventually evolves into highly n-doped semiconductors in sulfur-rich alloys. The synthesis of WS2xSe2-2x nanosheets with tunable optical and electronic properties represents a critical step toward rational design of 2D electronics with tailored spectral responses and device characteristics.
authors.forename: Xidong
authors.initials: X
authors.lastname: Duan
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Fan
authors.forename: Guolin
authors.initials: G
authors.lastname: Hao
authors.affiliation: School of Chemistry, Physics and Mechanical Engineering Faculty, Queensland University of Technology , Garden Point Campus, QLD 4001 Brisbane, Australia.
authors.forename: Liangzhi
authors.initials: L
authors.lastname: Kou
authors.forename: Udayabagya
authors.initials: U
authors.lastname: Halim
authors.forename: Honglai
authors.initials: H
authors.lastname: Li
authors.forename: Xueping
authors.initials: X
authors.lastname: Wu
authors.forename: Yicheng
authors.initials: Y
authors.lastname: Wang
authors.forename: Jianhui
authors.initials: J
authors.lastname: Jiang
authors.forename: Anlian
authors.initials: A
authors.lastname: Pan
authors.forename: Yu
authors.initials: Y
authors.lastname: Huang
authors.forename: Ruqin
authors.initials: R
authors.lastname: Yu
authors.forename: Xiangfeng
authors.initials: X
authors.lastname: Duan
keywords: Layered materials; band gap engineering; field effect transistor; semiconductor alloy; threshold voltage; transition metal dichalcogenide