title: Application of tungsten as a carbon sink for synthesis of large-domain uniform monolayer graphene free of bilayers/multilayers.
abstract: We have found that tungsten (W) foils can be used for controlling the carbon diffusion within copper (Cu) enclosures to synthesize large-domain bi-/multi-layer-free monolayer graphene via chemical vapor deposition. We have observed that bi-/multi-layer graphene that nucleate underneath the monolayer graphene can be selectively removed by a W foil placed inside of the Cu enclosure. Both X-ray photoelectron spectroscopy and X-ray diffraction reveal the formation of tungsten sub-carbide (W2C), suggesting the role of the W foil as a carbon sink that alters the carbon concentration inside of the enclosure. Consequently, the bi-/multi-layers appear to dissolve. Utilizing this selective removal process, we were able to demonstrate large-domain (>200 μm) monolayer graphene that is free of any bi-/multi-layers by using Cu double enclosures.
authors.affiliation: Department of Electrical Engineering and Computer Sciences, Cambridge, Massachusetts 02139, USA. jingkong@mit.edu.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Fang
authors.forename: Allen
authors.initials: A
authors.lastname: Hsu
authors.forename: Yong Cheol
authors.initials: YC
authors.lastname: Shin
authors.forename: Albert
authors.initials: A
authors.lastname: Liao
authors.forename: Shengxi
authors.initials: S
authors.lastname: Huang
authors.forename: Yi
authors.initials: Y
authors.lastname: Song
authors.forename: Xi
authors.initials: X
authors.lastname: Ling
authors.forename: Mildred S
authors.initials: MS
authors.lastname: Dresselhaus
authors.forename: Tomas
authors.initials: T
authors.lastname: Palacios
authors.forename: Jing
authors.initials: J
authors.lastname: Kong