High Thermal Conductivity in Wafer Scale Cubic Silicon Carbide Crystals

TL;DR

This study demonstrates that high-quality wafer-scale cubic silicon carbide exhibits record-high thermal conductivity, surpassing previous materials, due to its purity and crystal quality, making it promising for electronic and photonic applications.

Contribution

The paper reports the first observation of isotropic high thermal conductivity over 500 W/m·K in wafer-scale 3C-SiC crystals, resolving previous discrepancies and highlighting its potential for power electronics.

Findings

3C-SiC exhibits thermal conductivity over 500 W/m·K at room temperature.

Record-high in-plane and cross-plane thermal conductivities in 3C-SiC thin films.

High purity and crystal quality are key to the observed high thermal conductivity.

Abstract

High thermal conductivity electronic materials are critical components for high-performance electronic and photonic devices as either active functional materials or thermal management materials. We report an isotropic high thermal conductivity over 500 W m-1K-1 at room temperature in high-quality wafer-scale cubic silicon carbide (3C-SiC) crystals, which is the second highest among large crystals (only surpassed by diamond). Furthermore, the corresponding 3C-SiC thin films are found to have record-high in-plane and cross-plane thermal conductivity, even higher than diamond thin films with equivalent thicknesses. Our results resolve a long-lasting puzzle that the literature values of thermal conductivity for 3C-SiC are perplexingly lower than the structurally more complex 6H-SiC. Further analysis reveals that the observed high thermal conductivity in this work arises from the high purity and high crystal quality of 3C-SiC crystals which excludes the exceptionally strong defect-phonon scatterings in 3C-SiC. Moreover, by integrating 3C-SiC with other semiconductors by epitaxial growth, we show that the measured 3C-SiC-Si TBC is among the highest for semiconductor interfaces. These findings not only provide insights for fundamental phonon transport mechanisms, also suggest that 3C-SiC may constitute an excellent wide-bandgap semiconductor for applications of power electronics as either active components or substrates.