Near-Field Coupling with a Nanoimprinted Probe for Dark Exciton Nanoimaging in Monolayer WSe<sub>2</sub>
Junze Zhou, John C. Thomas, Elyse Barré, Edward S. Barnard, Archana Raja, Stefano Cabrini, Keiko Munechika, Adam Schwartzberg, Alexander Weber‐Bargioni
Abstract
High Resolution Image Download MS PowerPoint Slide Tip-enhanced photoluminescence (TRPL) is a powerful technique for spatially and spectrally probing local optical properties of 2-dimensional (2D) materials that are modulated by the local heterogeneities, revealing inaccessible dark states due to bright state overlap in conventional far-field microscopy at room temperature. While scattering-type near-field probes have shown the potential to selectively enhance and reveal dark exciton emission, their technical complexity and sensitivity can pose challenges under certain experimental conditions. Here, we present a highly reproducible and easy-to-fabricate near-field probe based on nanoimprint lithography and fiber-optic excitation and collection. The novel near-field measurement configuration provides an ∼3 orders of magnitude out-of-plane Purcell enhancement, diffraction-limited excitation spot, and subdiffraction hyperspectral imaging resolution (below 50 nm) of dark exciton emission. The effectiveness of this high spatial X D mapping technique was then demonstrated through reproducible hyperspectral mapping of oxidized sites and bubble areas.