Analysis of the Thermal Conductivity in Silicon Scallop Nanowires

Abstract

Silicon nanowires are attracting attention as strong candidates to replace conventional thermoelectric materials as they overcome the high thermal conductivity of bulk silicon and greatly improve thermoelectric conversion efficiency. In order to improve the thermoelectric efficiency, it is necessary to reduce the thermal conductivity, and the formation of the rough surface on the nanowire is a very effective method for lowering the thermal conductivity. In this paper, a scallop surface was formed on the vertical silicon nanowires by the BOSCH process and reported about 40% reduction in thermal conductivity compared to the Casimir limit. The reason for the decrease in thermal conductivity is due to the phonon backscattering, and the radiation analogy suggests the possibility of the backscattering that is difficult to explain with the phonon boundary scattering.