One-Dimensional Quantum Confinement Effect Modulated Thermoelectric Properties in InAs Nanowires

TL;DR

This study demonstrates how quantum confinement in InAs nanowires can modulate thermoelectric properties, revealing oscillations and the impact of disorder on thermoelectric performance at various temperatures.

Contribution

It provides experimental evidence of thermopower modulation via 1D sub-bands in InAs nanowires and highlights the role of scattering in thermoelectric behavior at practical temperatures.

Findings

Thermopower oscillations observed at low temperatures.

Gate voltage effectively modulates thermoelectric properties.

Disorder broadening reduces thermoelectric enhancement at 300K.

Abstract

We report electrical conductance and thermopower measurements on InAs nanowires synthesized by chemical vapor deposition. Gate modulation of the thermopower of individual InAs nanowires with diameter around 20nm is obtained over T=40 to 300K. At low temperatures (T< ~100K), oscillations in the thermopower and power factor concomitant with the stepwise conductance increases are observed as the gate voltage shifts the chemical potential of electrons in InAs nanowire through quasi-one-dimensional (1D) sub-bands. This work experimentally shows the possibility to modulate semiconductor nanowire's thermoelectric properties through the peaked 1D electronic density of states in the diffusive transport regime, a long-sought goal in nanostructured thermoelectrics research. Moreover, we point out the importance of scattering (or disorder) induced energy level broadening in smearing out the 1D confinement enhanced thermoelectric power factor at practical temperatures (e.g. 300K).