The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Claes Thelander

Claes Thelander

Associate Professor

Claes Thelander

Imaging the Thermalization of Hot Carriers after Thermionic Emission over a Polytype Barrier

Author

  • Fabian Könemann
  • I. Ju Chen
  • Sebastian Lehmann
  • Claes Thelander
  • Bernd Gotsmann

Summary, in English

The thermalization of nonequilibrium charge carriers is at the heart of thermoelectric energy conversion. In nanoscale systems, the equilibration length can be on the order of the system size, leading to a situation where thermoelectric effects need to be considered as spatially distributed, rather than localized at junctions. The energy exchange between charge carriers and phonons is of fundamental scientific and technological interest, but their assessment poses significant experimental challenges. We address these challenges by imaging the temperature change induced by Peltier effects in crystal phase engineered InAs nanowire (NW) devices. Using high-resolution scanning thermal microscopy (SThM), we study current-carrying InAs NWs, which feature a barrier segment of wurtzite (WZ) of varying length in a NW of otherwise zincblende (ZB) crystal phase. The energy barrier acts as a filter for electron transport around the Fermi energy, giving rise to a thermoelectric effect. We find that thermalization through electron-phonon heat exchange extends over the entire device. We analyze the temperature profile along a nanowire by comparing it to spatially dependent heat diffusion and electron thermalization models. We are able to extract the governing properties of the system, including the electron thermalization length of 223±9nm, Peltier coefficient and Seebeck coefficient introduced by the barrier of 39±7mV and 89±21μV/K, respectively, and a thermal conductivity along the wire axis of 8.9±0.5 W/m K. Finally, we compare two ways to extract the elusive thermal boundary conductance between the NW and underlying substrate.

Department/s

  • Solid State Physics
  • NanoLund: Center for Nanoscience

Publishing year

2020

Language

English

Publication/Series

Physical Review Applied

Volume

13

Issue

5

Document type

Journal article

Publisher

American Physical Society

Topic

  • Nano Technology
  • Condensed Matter Physics

Status

Published

ISBN/ISSN/Other

  • ISSN: 2331-7019