Article

An extended defect in graphene as a metallic wire

Department of Physics, University of South Florida, Tampa, FL 33620, USA.
Nature Nanotechnology (Impact Factor: 34.05). 03/2010; 5(5):326-9. DOI: 10.1038/nnano.2010.53
Source: PubMed

ABSTRACT

Many proposed applications of graphene require the ability to tune its electronic structure at the nanoscale. Although charge transfer and field-effect doping can be applied to manipulate charge carrier concentrations, using them to achieve nanoscale control remains a challenge. An alternative approach is 'self-doping', in which extended defects are introduced into the graphene lattice. The controlled engineering of these defects represents a viable approach to creation and nanoscale control of one-dimensional charge distributions with widths of several atoms. However, the only experimentally realized extended defects so far have been the edges of graphene nanoribbons, which show dangling bonds that make them chemically unstable. Here, we report the realization of a one-dimensional topological defect in graphene, containing octagonal and pentagonal sp(2)-hybridized carbon rings embedded in a perfect graphene sheet. By doping the surrounding graphene lattice, the defect acts as a quasi-one-dimensional metallic wire. Such wires may form building blocks for atomic-scale, all-carbon electronics.

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    • "So far, universal existence of GBs in graphene have also been confirmed in the transmission electron microscopy (TEM) and optical microscopy measurements [20] [21]. Recently, Lahiri, et al. [22] reported that structurally well-defined one-dimensional topological defect could be controllably introduced in epitaxial graphene, and found that such defects would yield a pronounced perturbation into the electronic structure. Undoubtedly, the domain size and the creation of localized electronic state upon a defect line will affect the electrical quality significantly. "
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    ABSTRACT: The polycrystalline structures for graphene are practically unavoidable by the currently existing growth routes, thus the scattering issue of electrons by grain boundary (GBs) becomes a theoretical and an experimental relevant one. Here, magnetic transport properties of the polycrystalline graphene nanoribbons (PGNRs) with a zigzag–armchair–zigzag structure are investigated systematically. It shows that GBs can induce significant localized electron states and magnetic ordering in the region consisting of GBs and armchair segment, and the interdomain electronic transmission across the GBs is transparent or blocked completely depending on the spin direction (α or β) of electrons as well as the microscopic details and relative orientation of GBs, which causes a special spin polarization for the magnetic transport. Especially, the perfect spin-filtering, spin-rectifying, and giant magnetoresistance effects can be realized simultaneously in such heterojunctions. These novel features can be rationalized by the spin splitting of molecular levels as well as the delocalization degree and parity limitation of molecular orbital wave functions in the scattering region serving as an extended molecule. Also shown is that PGNR-based heterojunctions possess a large range of magnetic behaviors with variation of its geometrical size.
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    • "Defects on two-dimensional (2D) materials were often considered as hindrance despite of potential controllability in electromagnetic and mechanical property of the materials (Lahiri et al., 2010; Yazyev & Louie, 2010; Attaccalite et al., 2011; Zhou et al., 2013a). For example, the actual performance of graphene devices failed to satisfy the expectations due to the inherent defect in them (Li et al., 2009). "
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    • "An extended line of defects (ELD) in graphene has been found using nickel [111] as substrate [51]. The authors propose that the defects involved are a combination of two pentagons and one octagon (5–8–5) forming a nanowire embedded in the graphene matrix (see Figure 9 "

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