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Electronic and plasmonic phenomena at graphene grain boundaries

TitleElectronic and plasmonic phenomena at graphene grain boundaries
Publication TypeJournal Article
Year of Publication2013
AuthorsFei, Z., Rodin A. S., Gannett W., Dai S., Regan W., Wagner M., Liu M. K., {McLeod} A. S., Dominguez G., Thiemens M., Neto Antonio Castro H., Keilmann F., Zettl A., Hillenbrand R., Fogler M. M., and Basov D. N.
JournalNature Nanotechnology
Date Published11/2013

Graphene, a two-dimensional honeycomb lattice of carbon atoms of great interest in (opto)electronics and plasmonics, can be obtained by means of diverse fabrication techniques, among which chemical vapour deposition ({CVD)} is one of the most promising for technological applications. The electronic and mechanical properties of {CVD-grown} graphene depend in large part on the characteristics of the grain boundaries. However, the physical properties of these grain boundaries remain challenging to characterize directly and conveniently. Here we show that it is possible to visualize and investigate the grain boundaries in {CVD-grown} graphene using an infrared nano-imaging technique. We harness surface plasmons that are reflected and scattered by the graphene grain boundaries, thus causing plasmon interference. By recording and analysing the interference patterns, we can map grain boundaries for a large-area {CVD} graphene film and probe the electronic properties of individual grain boundaries. Quantitative analysis reveals that grain boundaries form electronic barriers that obstruct both electrical transport and plasmon propagation. The effective width of these barriers ({\textasciitilde}10–20 nm) depends on the electronic screening and is on the order of the Fermi wavelength of graphene. These results uncover a microscopic mechanism that is responsible for the low electron mobility observed in {CVD-grown} graphene, and suggest the possibility of using electronic barriers to realize tunable plasmon reflectors and phase retarders in future graphene-based plasmonic circuits.


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