Non-invasive local (photo)conductivity measurements of metallic and semiconductor nanowires in the near-field

The capability of THz-time domain spectroscopy (TDS) for the non-invasive extraction of the conductive properties of metal and semiconductor surfaces is essential for advancements in material science and device analysis. Here, we demonstrate that this technique can be successfully applied to image and analyze sub-diffraction inhomogeneities using THz near-field microscopy. Additionally, a novel total internal reflection geometry enables time-resolved THz time-domain near-field microscopy using ultrashort optical pulses on photoexcited semiconducting materials with a resolution of $< 50~\mu {\mathrm{ m}}$.