期刊
NATURE NANOTECHNOLOGY
卷 14, 期 2, 页码 145-+出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/s41565-018-0323-8
关键词
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资金
- Center for Excitonics, an Energy Frontier Research Center - US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences (BES) [DESC0001088]
- AFOSR [FA9550-16-1-0382]
- Gordon and Betty Moore Foundation's EPiQS Initiative [GBMF4541]
- National Science Foundation (NSF) [DMR-14-19807]
- Harvard CNS - NSF ECCS [1541959]
- STC Center for Integrated Quantum Materials, NSF grant [DMR-1231319]
When the Fermi level is aligned with the Dirac point of graphene, reduced charge screening greatly enhances electron-electron scattering(1-5). In an optically excited system, the kinematics of electron-electron scattering in Dirac fermions is predicted to give rise to novel optoelectronic phenomena(6-11). In this paper, we report on the observation of an intrinsic photocurrent in graphene, which occurs in a different parameter regime from all the previously observed photothermoelectric or photovoltaic photocurrents in graphene(12-20): the photocurrent emerges exclusively at the charge neutrality point, requiring no finite doping. Unlike other photocurrent types that are enhanced near p-n or contact junctions, the photocurrent observed in our work arises near the edges/corners. By systematic data analyses, we show that the phenomenon stems from the unique electron-electron scattering kinematics in charge-neutral graphene. Our results not only highlight the intriguing electron dynamics in the optoelectronic response of Dirac fermions, but also offer a new scheme for photodetection and energy harvesting applications based on intrinsic, charge-neutral Dirac fermions.
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