Noise thermometry applied to thermoelectric measurements in InAs nanowires

TL;DR

This study uses noise thermometry to accurately measure thermoelectric properties in InAs nanowires at low temperature, revealing mesoscopic fluctuations and enabling improved thermal biasing techniques.

Contribution

It introduces a primary electronic noise thermometry method for calibrating thermal bias and demonstrates its application in measuring thermopower in InAs nanowires.

Findings

Shot noise indicates elastic diffusive transport with negligible electron-phonon interaction.

Thermoelectric Seebeck coefficient shows strong mesoscopic fluctuations with gate voltage.

Contact heating scheme effectively creates thermal bias for thermopower measurement.

Abstract

We apply noise thermometry to characterize charge and thermoelectric transport in single InAs nanowires (NWs) at a bath temperature of 4.2 K. Shot noise measurements identify elastic diffusive transport in our NWs with negligible electron-phonon interaction. This enables us to set up a measurement of the diffusion thermopower. Unlike in previous approaches, we make use of a primary electronic noise thermometry to calibrate a thermal bias across the NW. In particular, this enables us to apply a contact heating scheme, which is much more efficient in creating the thermal bias as compared to conventional substrate heating. The measured thermoelectric Seebeck coefficient exhibits strong mesoscopic fluctuations in dependence on the back-gate voltage that is used to tune the NW carrier density. We analyze the transport and thermoelectric data in terms of approximate Mott's thermopower relation and to evaluate a gate-voltage to Fermi energy conversion factor.