title: Atomic-scale evidence for potential barriers and strong carrier scattering at graphene grain boundaries: a scanning tunneling microscopy study.
abstract: We use scanning tunneling microscopy and spectroscopy to examine the electronic nature of grain boundaries (GBs) in polycrystalline graphene grown by chemical vapor deposition (CVD) on Cu foil and transferred to SiO(2) substrates. We find no preferential orientation angle between grains, and the GBs are continuous across graphene wrinkles and SiO(2) topography. Scanning tunneling spectroscopy shows enhanced empty states tunneling conductance for most of the GBs and a shift toward more n-type behavior compared to the bulk of the graphene. We also observe standing wave patterns adjacent to GBs propagating in a zigzag direction with a decay length of ~1 nm. Fourier analysis of these patterns indicates that backscattering and intervalley scattering are the dominant mechanisms responsible for the mobility reduction in the presence of GBs in CVD-grown graphene.
authors.affiliation: Department of Electrical & Computer Engineering, University of Illinois, Urbana-Champaign, Illinois 61801, USA. jkoepke@illinois.edu
authors.forename: Justin C
authors.initials: JC
authors.lastname: Koepke
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Wood
authors.forename: David
authors.initials: D
authors.lastname: Estrada
authors.forename: Zhun-Yong
authors.initials: ZY
authors.lastname: Ong
authors.forename: Kevin T
authors.initials: KT
authors.lastname: He
authors.forename: Eric
authors.initials: E
authors.lastname: Pop
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Lyding
mesh_terms: D004579:Electron Transport; D006108:Graphite / Q000737:chemistry*; D008422:Materials Testing; D016252:Microscopy, Scanning Tunneling / Q000379:methods*; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D006108:Graphite