Geometrically Enhanced Thermoelectric Effects in Graphene Nanoconstrictions

Achim Harzheim, Jean Spiece, Charalambos Evangeli, Edward McCann, Vladimir Falko, Yuewen Sheng, Jamie H. Warner, G. Andrew D. Briggs, Jan A. Mol, Pascal Gehring, Oleg V. Kolosov

Research output: Contribution to journalArticleScientificpeer-review

19 Citations (Scopus)
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Abstract

The influence of nanostructuring and quantum confinement on the thermoelectric properties of materials has been extensively studied. While this has made possible multiple breakthroughs in the achievable figure of merit, classical confinement, and its effect on the local Seebeck coefficient has mostly been neglected, as has the Peltier effect in general due to the complexity of measuring small temperature gradients locally. Here we report that reducing the width of a graphene channel to 100 nm changes the Seebeck coefficient by orders of magnitude. Using a scanning thermal microscope allows us to probe the local temperature of electrically contacted graphene two-terminal devices or to locally heat the sample. We show that constrictions in mono- and bilayer graphene facilitate a spatially correlated gradient in the Seebeck and Peltier coefficient, as evidenced by the pronounced thermovoltage Vth and heating/cooling response TPeltier, respectively. This geometry dependent effect, which has not been reported previously in 2D materials, has important implications for measurements of patterned nanostructures in graphene and points to novel solutions for effective thermal management in electronic graphene devices or concepts for single material thermocouples.

Original languageEnglish
Pages (from-to)7719-7725
JournalNano Letters
DOIs
Publication statusPublished - 2018

Keywords

  • graphene nanostructures
  • Peltier
  • scanning thermal microscopy
  • Seebeck
  • Thermoelectrics

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