Quantum Confinement Suppressing Electronic Heat Flow below the Wiedemann–Franz Law

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.

A Strongly Correlated Quantum Dot Heat Engine with Optimal Performance: A Nonequilibrium Green's Function Approach

“…[ 10–18 ] Due to quantum confinement and Coulomb blockade (CB) effects on QD, these low‐dimensional heat engines are more efficient at converting thermal energy into electrical energy than their bulk counterparts. [ 19–24 ] The enhancement of thermoelectric efficiency in QD heat engines is due to the strong violation of the Wiedemann–Franz law [ 25–31 ] and the significant drop in lattice thermal conductivity. [ 32–35 ]…”

“…[10][11][12][13][14][15][16][17][18] Due to quantum confinement and Coulomb blockade (CB) effects on QD, these low-dimensional heat engines are more efficient at converting thermal energy into electrical energy than their bulk counterparts. [19][20][21][22][23][24] The enhancement of thermoelectric efficiency in QD heat engines is due to the strong violation of the Wiedemann-Franz law [25][26][27][28][29][30][31] and the significant drop in lattice thermal conductivity. [32][33][34][35] In QD heat engines, electrons tunnel from the left hot reservoir to the QD and then to the right cold reservoir, resulting in a thermovoltage, or voltage caused by the temperature difference between the reservoirs due to the Seebeck effect.…”

A Strongly Correlated Quantum-Dot Heat Engine with Optimal Performance: An Non-equilibrium Green's function Approach

“…These particle-exchange heat engines consist of quantum dot(s) connected to metallic source and drain reservoirs by tunnel junctions [8][9][10][11][12][13][14][15]. Due to quantum confinement and Coulomb blockade (CB) effects on QD, these low-dimensional heat engines are more efficient at converting thermal energy into electrical energy than their bulk counterparts [16][17][18][19][20][21]. The enhancement of thermoelectric efficiency in QD heat engines is due to the strong violation of the Wiedemann-Franz law [22][23][24][25][26][27][28] and the significant drop in lattice thermal conductivity [29][30][31][32].…”