Cryogenic Nano-Imaging of Excitons in a Monolayer Semiconductor
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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866908748761530368 |
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| author | Roche, Anna Koehler, Michael R. Mandrus, David G. Taniguchi, Takashi Watanabe, Kenji Schaibley, John R. LeRoy, Brian J. |
| author_facet | Roche, Anna Koehler, Michael R. Mandrus, David G. Taniguchi, Takashi Watanabe, Kenji Schaibley, John R. LeRoy, Brian J. |
| contents | Excitons, Coulomb bound electron-hole pairs, dominate the optical response of two-dimensional semiconductors across near-infrared and visible frequencies due to their large binding energy and prominent oscillator strength. Previous measurements of excitons in 2D semiconductors have primarily relied on far-field optical spectroscopy techniques which are diffraction limited to several hundred nanometers. To precisely image nanoscale spatial disorder requires an order of magnitude increase in resolution capabilities. Here, we present a study of the exciton spectra of monolayer MoSe2 in the visible range using a cryogenic scattering-type scanning near field optical microscope (s-SNOM) operating down to 11 K. By mapping the spatial variation in the exciton resonance across an hBN encapsulated MoSe2 monolayer, we achieve sub-50 nm spatial resolution and energy resolution below 1 meV. We further investigate the material's near-field spectra and dielectric function, demonstrating the ability of cryogenic visible s-SNOM to reveal nanoscale disorder. Comparison to room temperature measurements illustrate the enhanced capabilities of cryogenic s-SNOM to reveal fine-scale material heterogeneity. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2503_12690 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Cryogenic Nano-Imaging of Excitons in a Monolayer Semiconductor Roche, Anna Koehler, Michael R. Mandrus, David G. Taniguchi, Takashi Watanabe, Kenji Schaibley, John R. LeRoy, Brian J. Mesoscale and Nanoscale Physics Applied Physics Excitons, Coulomb bound electron-hole pairs, dominate the optical response of two-dimensional semiconductors across near-infrared and visible frequencies due to their large binding energy and prominent oscillator strength. Previous measurements of excitons in 2D semiconductors have primarily relied on far-field optical spectroscopy techniques which are diffraction limited to several hundred nanometers. To precisely image nanoscale spatial disorder requires an order of magnitude increase in resolution capabilities. Here, we present a study of the exciton spectra of monolayer MoSe2 in the visible range using a cryogenic scattering-type scanning near field optical microscope (s-SNOM) operating down to 11 K. By mapping the spatial variation in the exciton resonance across an hBN encapsulated MoSe2 monolayer, we achieve sub-50 nm spatial resolution and energy resolution below 1 meV. We further investigate the material's near-field spectra and dielectric function, demonstrating the ability of cryogenic visible s-SNOM to reveal nanoscale disorder. Comparison to room temperature measurements illustrate the enhanced capabilities of cryogenic s-SNOM to reveal fine-scale material heterogeneity. |
| title | Cryogenic Nano-Imaging of Excitons in a Monolayer Semiconductor |
| topic | Mesoscale and Nanoscale Physics Applied Physics |
| url | https://arxiv.org/abs/2503.12690 |