High thermoelectricpower factor in graphene/hBN devices

Junxi Duan, Xiaoming Wang, Xinyuan Lai, Guohong Li, Kenji Watanabe, Takashi Taniguchi, Mona Zebarjadi*, Eva Y. Andrei

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

128 Citations (Scopus)

Abstract

Fast and controllable cooling at nanoscales requires a combination of highly efficient passive cooling and active cooling. Although passive cooling in graphene-based devices is quite effective due to graphene's extraordinary heat conduction, active cooling has not been considered feasible due to graphene's low thermoelectric power factor. Here, we show that the thermoelectric performance of graphene can be significantly improved by using hexagonal boron nitride (hBN) substrates instead of SiO2. We find the room temperature efficiency of active cooling in the device, as gauged by the power factor times temperature, reaches values as high as 10.35 W·m-1·K-1, corresponding to more than doubling the highest reported room temperature bulk power factors, 5 W·m-1·K-1, in YbAl3, and quadrupling the best 2D power factor, 2.5W·m-1·K-1, in MoS2. We further show that the Seebeck coefficient provides a direct measure of substrate-induced random potential fluctuations and that their significant reduction for hBN substrates enables fast gate-controlled switching of the Seebeck coefficient polarity for applications in integrated active cooling devices.

Original languageEnglish
Pages (from-to)14272-14276
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume113
Issue number50
DOIs
Publication statusPublished - 13 Dec 2016
Externally publishedYes

Keywords

  • Electron-hole puddles
  • Graphene
  • Screened coulomb scattering
  • Seebeck coefficient
  • Thermoelectric power factor

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