Subwavelength Terahertz Imaging of Graphene Photoconductivity.

Hornett, Samuel M; Stantchev, Rayko I; Vardaki, Martha Z; Beckerleg, Chris; Hendry, Euan · Nano Lett · 2016

basic_science · Level V

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Abstract

Using a spatially structured, optical pump pulse with a terahertz (THz) probe pulse, we are able to determine spatial variations of the ultrafast THz photoconductivity with subwavelength resolution (75 μm ≈ λ/5 at 0.8 THz) in a planar graphene sample. We compare our results to Raman spectroscopy and correlate the existence of the spatial inhomogeneities between the two measurements. We find a strong correlation with inhomogeneity in electron density. This demonstrates the importance of eliminating inhomogeneities in doping density during CVD growth and fabrication for photoconductive devices.