Thermal Conductivity of Cubic Silicon Carbide Single Crystals Heavily Doped by Nitrogen

TL;DR

This study experimentally investigates how heavy nitrogen doping affects the thermal conductivity of cubic silicon carbide, revealing a significant reduction and providing insights into phonon scattering mechanisms relevant for thermal management in electronics.

Contribution

First experimental measurement of heavily nitrogen-doped 3C-SiC thermal conductivity, comparing results with theoretical predictions and exploring scattering mechanisms.

Findings

Nitrogen doping reduces thermal conductivity by up to 30%.

Measured scattering is less intense than theoretical predictions.

Electron-phonon scattering impact may be smaller than previously thought.

Abstract

High-purity cubic silicon carbide possesses the second-highest thermal conductivity among large-scale crystals, surpassed only by diamond, making it crucial for practical applications of thermal management. Recent theoretical studies predict that heavy doping reduces the thermal conductivity of 3C-SiC via phonon-defect and phonon-electron scattering. However, experimental evidence has been limited. In this work, we report the thermal conductivity of heavily nitrogen doped 3C SiC single crystals, grown using the top-seeded solution growth method, measured via time domain thermoreflectance. Our results show that a significant reduction (up to 30%) in thermal conductivity is observed with nitrogen doping concentrations around 1020 cm-3. A comparison with theoretical calculations indicates less intensive scatterings are observed in the measured thermal conductivity. We speculate that the electron-phonon scattering may have a smaller impact than previously anticipated or the distribution of defects are nonuniform which leads to less intensive scatterings. These findings shed light on understanding the doping effects on thermal transport in semiconductors and support further exploration of 3C SiC for thermal management in electronics.