title: Layer-modulated synthesis of uniform tungsten disulfide nanosheet using gas-phase precursors.
abstract: The synthesis of layered transition-metal-disulfide (MS2, M = Mo, W) nanosheets with layer controllability and large-area uniformity is an essential requirement for their application in electronic and optical devices. In this report, we describe a synthesis process of WS2 nanosheets with layer controllability and high uniformity using chemical vapor deposition (CVD) and WCl6 and H2S as gas-phase precursors. Through this process, we can systematically modulate the thickness of WS2 nanosheets by controlling the duration of the reaction between WCl6 and H2S. The CVD-grown WS2 nanosheets exhibit good stoichiometry as well as dependencies of a clear Raman shift and bandgap on the number of layers. These properties are confirmed by X-ray photoemission spectroscopy, Raman spectroscopy, and photoluminescence measurements. The number of layers of WS2 nanosheets is confirmed by atomic force microscopy. Finally, we demonstrate the fabrication and performance of a photodetector based on a hybrid structure consisting of graphene and a WS2 nanosheet.
authors.affiliation: School of Electrical and Electronics Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul, 120-749, Republic of Korea. hyungjun@yonsei.ac.kr.
authors.forename: Jusang
authors.initials: J
authors.lastname: Park
authors.forename: Wonseon
authors.initials: W
authors.lastname: Lee
authors.forename: Taejin
authors.initials: T
authors.lastname: Choi
authors.forename: Sung-Hwan
authors.initials: SH
authors.lastname: Hwang
authors.forename: Jae Min
authors.initials: JM
authors.lastname: Myoung
authors.forename: Jae-Hoon
authors.initials: JH
authors.lastname: Jung
authors.forename: Soo-Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Hyungjun
authors.initials: H
authors.lastname: Kim