Nano-imaging photoresponse in a moiré unit cell of minimally twisted bilayer graphene
| Autor: | Iacopo Torre, Takashi Taniguchi, Roshan Krishna Kumar, Frank H. L. Koppens, David Barcons-Ruiz, Kenji Watanabe, Niels C. H. Hesp, Hanan Herzig Sheinfux |
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| Rok vydání: | 2021 |
| Předmět: |
Materials science
Electronic properties and materials Superlattice Science General Physics and Astronomy 02 engineering and technology 01 natural sciences General Biochemistry Genetics and Molecular Biology Article law.invention Near-infrared spectroscopy law 0103 physical sciences Nano Spatial dependence 010306 general physics Nanoscopic scale Photocurrent Multidisciplinary business.industry Graphene General Chemistry Moiré pattern 021001 nanoscience & nanotechnology Optical properties and devices Optoelectronics 0210 nano-technology business Bilayer graphene |
| Zdroj: | Nature Communications Nature Communications, Vol 12, Iss 1, Pp 1-8 (2021) |
| ISSN: | 2041-1723 |
| DOI: | 10.1038/s41467-021-21862-5 |
| Popis: | Graphene-based moiré superlattices have recently emerged as a unique class of tuneable solid-state systems that exhibit significant optoelectronic activity. Local probing at length scales of the superlattice should provide deeper insight into the microscopic mechanisms of photoresponse and the exact role of the moiré lattice. Here, we employ a nanoscale probe to study photoresponse within a single moiré unit cell of minimally twisted bilayer graphene. Our measurements reveal a spatially rich photoresponse, whose sign and magnitude are governed by the fine structure of the moiré lattice and its orientation with respect to measurement contacts. This results in a strong directional effect and a striking spatial dependence of the gate-voltage response within the moiré domains. The spatial profile and carrier-density dependence of the measured photocurrent point towards a photo-thermoelectric induced response that is further corroborated by good agreement with numerical simulations. Our work shows sub-diffraction photocurrent spectroscopy is an exceptional tool for uncovering the optoelectronic properties of moiré superlattices. Here, the authors use a nanoscale probe to study the photoresponse within a single moiré unit cell of minimally twisted bilayer graphene, and observe an intricate photo-thermoelectric response attributed to the Seebeck coefficient variation at AB-BA domain boundaries. |
| Databáze: | OpenAIRE |
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