title: Layer-controlled, wafer-scale, and conformal synthesis of tungsten disulfide nanosheets using atomic layer deposition.
abstract: The synthesis of atomically thin transition-metal disulfides (MS2) with layer controllability and large-area uniformity is an essential requirement for their application in electronic and optical devices. In this work, we describe a process for the synthesis of WS2 nanosheets through the sulfurization of an atomic layer deposition (ALD) WO3 film with systematic layer controllability and wafer-level uniformity. The X-ray photoemission spectroscopy, Raman, and photoluminescence measurements exhibit that the ALD-based WS2 nanosheets have good stoichiometry, clear Raman shift, and bandgap dependence as a function of the number of layers. The electron mobility of the monolayer WS2 measured using a field-effect transistor (FET) with a high-k dielectric gate insulator is shown to be better than that of CVD-grown WS2, and the subthreshold swing is comparable to that of an exfoliated MoS2 FET device. Moreover, by utilizing the high conformality of the ALD process, we have developed a process for the fabrication of WS2 nanotubes.
authors.affiliation: School of Electrical and Electronics Engineering and §Department of Materials Science and Engineering, Yonsei University , Seoul 120-749, Korea.
authors.forename: Jeong-Gyu
authors.initials: JG
authors.lastname: Song
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: Hanearl
authors.initials: H
authors.lastname: Jung
authors.forename: Chang Wan
authors.initials: CW
authors.lastname: Lee
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: Clement
authors.initials: C
authors.lastname: Lansalot-Matras
authors.forename: Hyungjun
authors.initials: H
authors.lastname: Kim