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ORIGINAL RESEARCH article

Front. Photonics

Sec. Terahertz and Microwave Photonics

Volume 6 - 2025 | doi: 10.3389/fphot.2025.1638350

This article is part of the Research TopicSurfaces for Enhanced Terahertz Radiation Generation and ManipulationView all articles

Terahertz photoconductive atomic force microscopy of few-layer graphene flakes

Provisionally accepted
Erica FragomeniErica Fragomeni1Fritz BerkmannFritz Berkmann2Maria Eleonora TemperiniMaria Eleonora Temperini1Leonetta BaldassarreLeonetta Baldassarre1Michele OrtolaniMichele Ortolani1Valeria GilibertiValeria Giliberti3Tommaso VenanziTommaso Venanzi3*
  • 1Universita degli Studi di Roma La Sapienza, Rome, Italy
  • 2Brandenburgische Technische Universitat Cottbus-Senftenberg, Cottbus, Germany
  • 3Istituto Italiano di Tecnologia Center for Life Nano- & Neuro-Science, Rome, Italy

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Reaching nanometric spatial resolution in terahertz (THz) nanoimaging provides a powerful tool for the characterization of photonic devices. Here, we couple a THz source to a conductive atomic force microscope to measure the THz photo-induced current with nanometric spatial resolution. We aim at measuring the THz photo-induced current of few-layer graphene flakes with a platinum nanometric probe that acts both as THz field-enhancement antenna and as metal counter-electrode that forms a nanojunction. The THz beam is generated at 0.61 THz by an amplifier-multiplier chain. THz photo-induced current signals are detected and compared with the current-voltage characteristics. With this method, we map nanometric charge puddles in few-layer graphene flakes, and observe evidence of THz rectification at the platinum-graphene nanojunction. The local junction characteristic can be used to assess the surface quality of 2D-material flakes.

Keywords: AFM, THz, Photocurrent, THz nanoimaging, Graphene

Received: 30 May 2025; Accepted: 25 Jul 2025.

Copyright: © 2025 Fragomeni, Berkmann, Temperini, Baldassarre, Ortolani, Giliberti and Venanzi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Tommaso Venanzi, Istituto Italiano di Tecnologia Center for Life Nano- & Neuro-Science, Rome, Italy

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Supplementary Material