Remarkably suppressed lattice thermal conductivity of InAs nanowires by surface electron–phonon coupling

Abstract

The electron accumulation layer at the semiconductor nanowire surface can lead to intriguing transport phenomena and novel electronic applications. While much progress has been made in uncovering the effect of electron–phonon interactions on phonon transport in heavily doped semiconductors, the roles of the surface charge accumulation layer on thermal transport remain elusive. In this work, through measuring electrical and thermal conductivities of InAs nanowires of various diameters, we report a remarkable suppression of lattice thermal conductivity due to surface electron–phonon coupling. Contrary to the classical size effect due to electron-boundary scattering, the measured electrical conductivity of InAs nanowires increases as the diameter decreases. This observation stems from the enhanced contribution of surface electrons in smaller-diameter nanowires, which also renders a comparable electronic contribution to thermal conductivity alongside phonons. The extracted lattice thermal conductivity at room temperature is reduced by ∼73% compared to previously reported values and those predicted by first-principles calculations for intrinsic InAs nanowires. This discrepancy is well explained by the transport models incorporating both surface electron–phonon coupling and phonon-boundary scattering at the nanowire surface. These findings not only provide direct experimental data for quantifying the impact of surface electron–phonon interactions on lattice thermal conductivity but also highlight the potential of surface-state engineering as a viable strategy for tailoring thermal transport in semiconductors for thermoelectric and nanoelectronic applications.