Competing Channels for Hot-Electron Cooling in Graphene
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PhysRevLett.112.247401.pdf
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Author(s)
Ma, Qiong
Gabor, Nathaniel M.
Nair, Nityan L.
Watanabe, Kenji
Taniguchi, Takashi
Jarillo-Herrero, Pablo
Andersen, Trond
Date Issued
June 2014
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Ma, Qiong, Nathaniel M. Gabor, Trond I. Andersen, Nityan L. Nair, Kenji Watanabe, Takashi Taniguchi, and Pablo Jarillo-Herrero. “Competing Channels for Hot-Electron Cooling in Graphene.” Physical Review Letters 112, no. 24 (June 2014). © 2014 American Physical Society
Version
Final published version
Abstract
We report on temperature-dependent photocurrent measurements of high-quality dual-gated monolayer graphene p−n junction devices. A photothermoelectric effect governs the photocurrent response in our devices, allowing us to track the hot-electron temperature and probe hot-electron cooling channels over a wide temperature range (4 to 300 K). At high temperatures (T > T[superscript *]), we found that both the peak photocurrent and the hot spot size decreased with temperature, while at low temperatures (T < T[superscript *]), we found the opposite, namely that the peak photocurrent and the hot spot size increased with temperature. This nonmonotonic temperature dependence can be understood as resulting from the competition between two hot-electron cooling pathways: (a) (intrinsic) momentum-conserving normal collisions that dominates at low temperatures and (b) (extrinsic) disorder-assisted supercollisions that dominates at high temperatures. Gate control in our high-quality samples allows us to resolve the two processes in the same device for the first time. The peak temperature T[superscript *] depends on carrier density and disorder concentration, thus allowing for an unprecedented way of controlling graphene’s photoresponse.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PhysRevLett.112.247401
