Measurement of Thermal Conductivity of Silicon-Carbon Nanograins by Optothermal Raman Spectroscopy

Abstract

Optothermal Raman spectroscopy is a steady-state technique for measuring the thermal conductivity of materials. In this method, Raman spectroscopy is used to measure the local temperature rise of the sample, using the excitation laser as a heat source. Optothermal Raman is used to measure the thermal conductivity of silicon-carbon nanograins mixtures as a function of carbon and silicon content, to determine the effect of boundaries on nanoscale heat transport experimentally. It is found that the thermal conductivity of silicon-carbon nanograins mixtures varies rapidly between 4.3 W/m.K and 15.3 W/m.K as a function of silicon and carbon content. We thus demonstrate that optothermal Raman spectroscopy is an effective non-destructive method for measuring the thermal conductivity of random materials and that the thermal conductivity of silicon-carbon nanograins mixtures is highly sensitive to the ratio of silicon-to-carbon content. In other words, we found that grain boundary density significantly affects nanoscale heat transport. We hope that our work will pave the way for an experimental study of nanoscale thermal resistance, which has remained obscure to scientists