Fig. 1: Near-field nano-probing of excitons in atomically thin transition metal dichalcogendies (TMDs).
From: Nano-spectroscopy of excitons in atomically thin transition metal dichalcogenides
a Schematic illustration of near-field measurement of excitons. The metallized AFM tip is illuminated by focused incident light and the tip-scattered light is collected. Pairs of electrons and holes with strong Coulomb interactions in atomically thin TMDs form excitons with large binding energies. The nanoscale response of excitons is extracted from the back-scattered light. b Scanning the tip across the TMD sample allows one to investigate the excitonic response below the diffraction limit and extract the dielectric function at the nanometer scale. The inset shows the dielectric function of monolayer WSe2 from ref. 61 c An AFM topographic image of the TMDs in this study. The height difference between the left and right regions is due to the h-BN terrace. d, e Near-field images of normalized scattering amplitude \({s}_{5}\) and phase \({\varphi }_{4}\) on the same region of (c). The excitation energy is 1.68 eV. The dashed bright and blue lines trace the edges of the different sample regions. The dashed rectangle marks the position of Fig. 2a.
