title: Control and characterization of individual grains and grain boundaries in graphene grown by chemical vapour deposition.
abstract: The strong interest in graphene has motivated the scalable production of high-quality graphene and graphene devices. As the large-scale graphene films synthesized so far are typically polycrystalline, it is important to characterize and control grain boundaries, generally believed to degrade graphene quality. Here we study single-crystal graphene grains synthesized by ambient chemical vapour deposition on polycrystalline Cu, and show how individual boundaries between coalescing grains affect graphene's electronic properties. The graphene grains show no definite epitaxial relationship with the Cu substrate, and can cross Cu grain boundaries. The edges of these grains are found to be predominantly parallel to zigzag directions. We show that grain boundaries give a significant Raman 'D' peak, impede electrical transport, and induce prominent weak localization indicative of intervalley scattering in graphene. Finally, we demonstrate an approach using pre-patterned growth seeds to control graphene nucleation, opening a route towards scalable fabrication of single-crystal graphene devices without grain boundaries.
authors.affiliation: Center for Advanced Materials and Department of Electrical and Computer Engineering, University of Houston, Houston, Texas 77204, USA. qingkai.yu@txstate.edu
authors.forename: Qingkai
authors.initials: Q
authors.lastname: Yu
authors.forename: Luis A
authors.initials: LA
authors.lastname: Jauregui
authors.forename: Wei
authors.initials: W
authors.lastname: Wu
authors.forename: Robert
authors.initials: R
authors.lastname: Colby
authors.forename: Jifa
authors.initials: J
authors.lastname: Tian
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Su
authors.forename: Helin
authors.initials: H
authors.lastname: Cao
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Liu
authors.forename: Deepak
authors.initials: D
authors.lastname: Pandey
authors.forename: Dongguang
authors.initials: D
authors.lastname: Wei
authors.forename: Ting Fung
authors.initials: TF
authors.lastname: Chung
authors.forename: Peng
authors.initials: P
authors.lastname: Peng
authors.forename: Nathan P
authors.initials: NP
authors.lastname: Guisinger
authors.forename: Eric A
authors.initials: EA
authors.lastname: Stach
authors.forename: Jiming
authors.initials: J
authors.lastname: Bao
authors.forename: Shin-Shem
authors.initials: SS
authors.lastname: Pei
authors.forename: Yong P
authors.initials: YP
authors.lastname: Chen