Competing Channels for Hot-Electron Cooling in Graphene [electronic resource]
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| Format: | Government Document Electronic eBook |
| Language: | English |
| Published: |
Washington, D.C. : Oak Ridge, Tenn. :
United States. Department of Energy. Office of Basic Energy Sciences ; distributed by the Office of Scientific and Technical Information, U.S. Department of Energy,
2014.
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| Abstract: | We report here on temperature-dependent photocurrent measurements of high-quality dual-gated monolayer graphene <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>p</mi><mtext>-</mtext><mi>n</mi></mrow></math></span> 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 (<span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi><mo>></mo><msup><mi>T</mi><mo>*</mo></msup></math></span>), we found that both the peak photocurrent and the hot spot size decreased with temperature, while at low temperatures (<span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi><mo><</mo><msup><mi>T</mi><mo>*</mo></msup></math></span>), 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 <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>T</mi><mo>*</mo></msup></math></span> depends on carrier density and disorder concentration, thus allowing for an unprecedented way of controlling graphene's photoresponse. |
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| Item Description: | Published through SciTech Connect. 06/19/2014. Physical Review Letters 112 24 ISSN 0031-9007 AM. Qiong Ma; Nathaniel M. Gabor; Trond I. Andersen; Nityan L. Nair; Kenji Watanabe; Takashi Taniguchi; Pablo Jarillo-Herrero. |
| Physical Description: | Article No. 247401 : digital, PDF file. |