Abstract
We demonstrate that 60-keV electron irradiation drives the diffusion of threefold-coordinated Si dopants in graphene by one lattice site at a time. First principles simulations reveal that each step is caused by an electron impact on a C atom next to the dopant. Although the atomic motion happens below our experimental time resolution, stochastic analysis of 38 such lattice jumps reveals a probability for their occurrence in a good agreement with the simulations. Conversions from three- to fourfold coordinated dopant structures and the subsequent reverse process are significantly less likely than the direct bond inversion. Our results thus provide a model of nondestructive and atomically precise structural modification and detection for two-dimensional materials.
Highlights
We demonstrate that 60-keV electron irradiation drives the diffusion of threefold-coordinated Si dopants in graphene by one lattice site at a time
At the same time, (S)TEM instruments can be turned into nanosculpting tools: for example, graphene ribbons with specific geometries [7], or perforations of controlled sizes [8,9], can be fabricated via adjustments of the local chemistry, electron beam energy, and density
Exchanging some of the carbon atoms by boron or nitrogen can result in an opening of the gap [12,13], while localized enhancements of plasmon resonances can be created around single silicon substitutions, which act as atomic antennas [14]
Summary
We demonstrate that 60-keV electron irradiation drives the diffusion of threefold-coordinated Si dopants in graphene by one lattice site at a time. The atomic motion happens below our experimental time resolution, stochastic analysis of 38 such lattice jumps reveals a probability for their occurrence in a good agreement with the simulations.
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