Ultrafast photo-thermoelectric currents in graphene junctions in the mid-infrared
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arXiv
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| Autori principali: | , , , , , , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2026
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| _version_ | 1866918387770195968 |
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| author | Pettinger, Nina Panhans, Michel Schmuck, Johannes Loy, Sebastian Zhou, Xiaoyi Dong, Chengye Robinson, Joshua A. Zherebtsov, Sergey Kastl, Christoph Ortmann, Frank Holleitner, Alexander W. |
| author_facet | Pettinger, Nina Panhans, Michel Schmuck, Johannes Loy, Sebastian Zhou, Xiaoyi Dong, Chengye Robinson, Joshua A. Zherebtsov, Sergey Kastl, Christoph Ortmann, Frank Holleitner, Alexander W. |
| contents | Graphene is widely recognized for its ultrafast and broadband photocurrent response, but whether the broadband ultrafast characteristics are preserved at mid-infrared wavelengths with photon energies below the optical phonon energy remains an open question. Here, we investigate the carrier dynamics in graphene junctions under mid-infrared excitation using an ultrafast pump-probe photocurrent spectroscopy. We utilize dual split gate devices to demonstrate that the photo-thermoelectric effect can dominate the photoresponse of graphene also for a mid-infrared femtosecond excitation. We observe that graphene retains its broadband photocurrent response in this spectral region, but the photocurrent relaxation time increases from ca. 2 ps below 8-9 micrometer up to 3 ps at longer mid-infrared wavelengths. The absence of a pronounced phonon bottleneck in the decay dynamics at room temperature suggests an efficient interplay of electron-electron and electron-phonon scattering even for photon energies below the optical phonon energy in graphene. The observed wavelength dependence of the photocurrent relaxation times is consistent with energy-dependent theoretical relaxation times as derived from a microscopic transport theory of graphene that includes electron-phonon coupling within a Holstein-Peierls Hamiltonian. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_13457 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Ultrafast photo-thermoelectric currents in graphene junctions in the mid-infrared Pettinger, Nina Panhans, Michel Schmuck, Johannes Loy, Sebastian Zhou, Xiaoyi Dong, Chengye Robinson, Joshua A. Zherebtsov, Sergey Kastl, Christoph Ortmann, Frank Holleitner, Alexander W. Mesoscale and Nanoscale Physics Graphene is widely recognized for its ultrafast and broadband photocurrent response, but whether the broadband ultrafast characteristics are preserved at mid-infrared wavelengths with photon energies below the optical phonon energy remains an open question. Here, we investigate the carrier dynamics in graphene junctions under mid-infrared excitation using an ultrafast pump-probe photocurrent spectroscopy. We utilize dual split gate devices to demonstrate that the photo-thermoelectric effect can dominate the photoresponse of graphene also for a mid-infrared femtosecond excitation. We observe that graphene retains its broadband photocurrent response in this spectral region, but the photocurrent relaxation time increases from ca. 2 ps below 8-9 micrometer up to 3 ps at longer mid-infrared wavelengths. The absence of a pronounced phonon bottleneck in the decay dynamics at room temperature suggests an efficient interplay of electron-electron and electron-phonon scattering even for photon energies below the optical phonon energy in graphene. The observed wavelength dependence of the photocurrent relaxation times is consistent with energy-dependent theoretical relaxation times as derived from a microscopic transport theory of graphene that includes electron-phonon coupling within a Holstein-Peierls Hamiltonian. |
| title | Ultrafast photo-thermoelectric currents in graphene junctions in the mid-infrared |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2603.13457 |