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Atomic-scale optoelectronic devices: The case of substitutional Si atoms in monolayer graphene

W. Zhou. J. Lee, J. Nanda, S.J. Pennycook, S.T. Pantelides, and J.-C. Idrobo, Nature Nanotechnology, DOI: 10.1038/NNANO.2011.252 (2012)

Si atoms in monolayer graphene
(Left) Z-contrast image showing a substitutional Si atom in monolayer graphene. 
(Right)  plasmon map showing localized enhamcement.  The substitutional Si atom
acts as an atomic antenna, which results in an atomically localized  π+σ plasmon enhancement in graphene.  Scale bars, 0.2 nm

One of the recent paths being investigated by the electronic industry to make electronic devices smaller and faster, has been to use optical signals to transmit data instead of electronic signals.  This recent technology uses the plasmon response -a collective electronic excitation- of materials to transmit light at scales smaller than its wavelength. In this paper1, we used aberration-corrected scanning transmission electron microscopy to show that substitutional Si atoms in monolayer graphene act as atomic antennae in the petahertz (1015 Hz) frequency range, leading to surface plasmon responses at the subnanometer scale.  Our study suggests that by using different dopant atoms it may be possible to tune the frequency range where the plasmon enhancement occurs.  Furthermore, arrays of dopant atoms, at grain boundaries or the edges of ribbons for example, could act as optical waveguides. Our observations open up new possibilities for emerging technologies, suggesting that the physical limit for the size of plasmonic and optoelectronic devices can be scaled down to the single atom level.

 Oak Ridge National Laboratory