Abstract-All-electronic terahertz nanoscopy

Clemens Liewald, Stefan Mastel, Jeffrey Hesler, Andreas J. Huber, Rainer Hillenbrand, and Fritz Keilmann

https://www.osapublishing.org/optica/abstract.cfm?uri=optica-5-2-159&origin=search

Probing conductivity in a contactless way with nanoscale resolution is a pressing demand in such active fields as quantum materials, superconductivity, and molecular electronics. Here, we demonstrate a laser- and cryogen-free microwave-technology-based scattering-type scanning near-field optical microscope powered by an easily aligned free-space beam with a tunable frequency up to 0.75 THz. It uses Schottky diode components to record background-free amplitude and phase nano-images, for the first time in the terahertz range, which is uniquely sensitive for assessing conduction phenomena. Images of Si with doped nanostructures prove a conductance sensitivity corresponding to 1016  cm−3${10}^{16}{\mathrm{cm}}^{-3}$ mobile carriers, at 50 nm spatial resolution.

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