Topological Defects in Graphene: Dislocations and Grain Boundaries

Atomic structure of a grain boundary in graphene composed of dislocations, pairs of adjacent five- and seven-membered rings in the honeycomb lattice. First-principles calculations show that topological defects in graphene exhibit a rich variety of novel physical properties with potential implications for graphene-based electronics.

Oleg V. Yazyev
Steven G. Louie
Department of Physics
University of California, Berkeley
Materials Sciences Division
Lawrence Berkeley National Laboratory

Graphene is a recently discovered single-atomic-layer thick material with extraordinary physical properties and strong potential for replacing silicon in future electronic devices. Like any other real-world material, graphene is not free of imperfections. The focus of this theoretical work is on dislocations and grain boundaries – topological defects intrinsic to all polycrystalline materials. We show that a complete set of such structural irregularities can be systematically constructed from pentagons and heptagons embedded into the ideal lattice of graphene composed of hexagons. 

One example of such grain boundary structure is shown on the image. First-principles calculations show that grain boundaries in graphene have very intriguing electronic properties. While some grain boundaries are highly transparent for the transport of low-energy charge carriers, others are perfectly reflecting. An ability to control electronic transport in graphene by engineering such defects may lead to a new approach towards graphene-based electronics.

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The image has not been published. Reporters may freely use this image as long as they include the following credit: "Image courtesy of Oleg V. Yazyev and Steven G. Louie (UC Berkeley and LBNL)".  Please notify Oleg Yazyev before using the image.

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