Terahertz Near-field Inspection of Metallic Nano-gap Grating for Contrast-Enhanced Interaction with Two-dimensional Materials

Near-field inspection of metallic nano-gap gratings can be used to efficiently monitor terahertz (THz) interaction with two-dimensional (2D) materials. Localized field enhancement at the nano-gap region leads to higher absorption of the transmitted THz field and thus to a higher contrast of otherwise barely visible 2D materials. In this study, a significant enhancement of THz contrast was observed with high-resolution THz near-field imaging at graphene and MoS2. The resulting effective conductance and THz absorption have been quantified on a sub-wavelength scale using a photoconductive near-field microprobe-based THz-time-domain spectroscopy (TDS) system.