Quantum Confinement Suppressing Electronic Heat Flow below the Wiedemann-Franz Law.

Majidi, Danial; Josefsson, Martin; Kumar, Mukesh; Leijnse, Martin; Samuelson, Lars; Courtois, Hervé; Winkelmann, Clemens B; Maisi, Ville F · Nano Lett · 2022

basic_science · Level V

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Abstract

The Wiedemann-Franz law states that the charge conductance and the electronic contribution to the heat conductance are proportional. This sets stringent constraints on efficiency bounds for thermoelectric applications, which seek a large charge conduction in response to a small heat flow. We present experiments based on a quantum dot formed inside a semiconducting InAs nanowire transistor, in which the heat conduction can be tuned significantly below the Wiedemann-Franz prediction. Comparison with scattering theory shows that this is caused by quantum confinement and the resulting energy-selective transport properties of the quantum dot. Our results open up perspectives for tailoring independently the heat and electrical conduction properties in semiconductor nanostructures.