Direct mapping of local Seebeck coefficient in 2D material nanostructures via scanning thermal gate microscopy

Journal article (2020)

Authors

A. Harzheim University of Oxford
Charalambos Evangeli Lancaster University, University of Oxford
Oleg V. Kolosov Lancaster University
P. Gehring IMEC-Solliance, Kavli institute of nanoscience Delft, QN/van der Zant Lab - AS
Research Group
QN/van der Zant Lab (AS) (TU Delft)
Thermoelectric Seebeck coefficient Graphene nanostructures Scanning thermal gate microscopy Thermovoltage
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Published Date

2020

Language

English

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Faculty

Applied Sciences

Department

QN/Quantum Nanoscience

Research Group

QN/van der Zant Lab

Abstract

Studying local variations in the Seebeck coefficient of materials is important for understanding and optimizing their thermoelectric properties, yet most thermoelectric measurements are global over a whole device or material, thus overlooking spatial divergences in the signal and the role of local variation and internal structure. Such variations can be caused by local defects, metallic contacts or interfaces that often substantially influence thermoelectric properties, especially in two dimensional materials. Here, we demonstrate scanning thermal gate microscopy, a non-destructive method to obtain high resolution 2-dimensional maps of the thermovoltage, to study graphene samples. We demonstrate the efficiency of this newly developed method by measuring local Seebeck coefficient in a graphene ribbon and in a junction between single-layer and bilayer graphene.