Lightwave-driven tunneling spectroscopy of graphene nanoribbons

Novel atomic-scale electronics operating at optical frequencies require new tools that can characterize them and inform device fabrication. Lightwave-driven scanning tunneling microscopy is a promising new technique towards this purpose. By coupling free-space-propagating single-cycle terahertz transients to an atomically sharp metal tip, it achieves simultaneous sub-angstrom and sub-picosecond spatio-temporal resolution [1–7]. Here, we utilize terahertz scanning tunneling microscopy (THz-STM) and spectroscopy (THz-STS) to investigate seven-atom-wide graphene nanoribbons on an Au(111) surface and unveil highly localized wavefunctions that are inaccessible with conventional scanning tunneling microscopy [7]. Three-dimensional tomographic THz-STM imaging of the electron densities of the wavefunctions reveals a faster vertical decay of the valance band compared to the conduction band.

References

 

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