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Direct Visualization of Subnanometer Variations in the Excitonic Spectra of 2D/3D Semiconductor/Metal Heterostructures

2023; American Chemical Society; Volume: 23; Issue: 3 Linguagem: Inglês

10.1021/acs.nanolett.2c04749

1530-6992

Kate Reidy, Paulina Majchrzak, Benedikt Haas, Joachim Dahl Thomsen, Andrea Konečná, Eugene Park, Julian Klein, Alfred J. H. Jones, Klara Volckaert, Deepnarayan Biswas, Matthew D. Watson, Céphise Cacho, Prineha Narang, Christoph T. Koch, Søren Ulstrup, Frances M. Ross, Juan Carlos Idrobo,

Nanowire Synthesis and Applications

The integration of metallic contacts with two-dimensional (2D) semiconductors is routinely required for the fabrication of nanoscale devices. However, nanometer-scale variations in the 2D/metal interface can drastically alter the local optoelectronic properties. Here, we map local excitonic changes of the 2D semiconductor MoS2 in contact with Au. We utilize a suspended and epitaxially grown 2D/metal platform that allows correlated electron energy-loss spectroscopy (EELS) and angle resolved photoelectron spectroscopy (nanoARPES) mapping. Spatial localization of MoS2 excitons uncovers an additional EELS peak related to the MoS2/Au interface. NanoARPES measurements indicate that Au–S hybridization decreases substantially with distance from the 2D/metal interface, suggesting that the observed EELS peak arises due to dielectric screening of the excitonic Coulomb interaction. Our results suggest that increasing the van der Waals distance could optimize excitonic spectra of mixed-dimensional 2D/3D interfaces and highlight opportunities for Coulomb engineering of exciton energies by the local dielectric environment or moiré engineering.