Corrugated Si nanowires with reduced thermal conductivity for wide-temperature-range thermoelectricity

Abstract

We fabricated suspended straight and corrugated Si nanowires (NWs) from 55 nm thick Si-on-insulator and studied their thermal conductivity using Raman mapping. We demonstrate that corrugations induce 60%–70% reduction in NW thermal conductivity at temperatures 300–400 K. This proves the significance of ballistic phonon transport at these temperatures in sufficiently thin Si NWs and the efficiency of corrugations in thermal conductivity reduction for application in thermoelectricity. The experimental results presented here are in agreement with our NW thermal conductance calculation taking into account the effect of corrugations on low-frequency acoustic phonon branches.