title: Vapour phase growth and grain boundary structure of molybdenum disulphide atomic layers.
abstract: Single-layered molybdenum disulphide with a direct bandgap is a promising two-dimensional material that goes beyond graphene for the next generation of nanoelectronics. Here, we report the controlled vapour phase synthesis of molybdenum disulphide atomic layers and elucidate a fundamental mechanism for the nucleation, growth, and grain boundary formation in its crystalline monolayers. Furthermore, a nucleation-controlled strategy is established to systematically promote the formation of large-area, single- and few-layered films. Using high-resolution electron microscopy imaging, the atomic structure and morphology of the grains and their boundaries in the polycrystalline molybdenum disulphide atomic layers are examined, and the primary mechanisms for grain boundary formation are evaluated. Grain boundaries consisting of 5- and 7- member rings are directly observed with atomic resolution, and their energy landscape is investigated via first-principles calculations. The uniformity in thickness, large grain sizes, and excellent electrical performance signify the high quality and scalable synthesis of the molybdenum disulphide atomic layers.
authors.affiliation: Department of Mechanical Engineering and Materials Science, Rice University, Houston, Texas 77005, USA.
authors.forename: Sina
authors.initials: S
authors.lastname: Najmaei
authors.forename: Zheng
authors.initials: Z
authors.lastname: Liu
authors.forename: Wu
authors.initials: W
authors.lastname: Zhou
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Zou
authors.forename: Gang
authors.initials: G
authors.lastname: Shi
authors.forename: Sidong
authors.initials: S
authors.lastname: Lei
authors.forename: Boris I
authors.initials: BI
authors.lastname: Yakobson
authors.forename: Juan-Carlos
authors.initials: JC
authors.lastname: Idrobo
authors.forename: Pulickel M
authors.initials: PM
authors.lastname: Ajayan
authors.forename: Jun
authors.initials: J
authors.lastname: Lou