Thermal conductivity of cubic silicon carbide single crystals heavily doped by nitrogen

Abstract

High-purity single-crystal wide-bandgap semiconductor cubic silicon carbide (3C–SiC) has the second-highest thermal conductivity among wafer-scale crystals (after diamond), making it ideal for thermal management in electronic devices. However, doping—essential for electrical property tuning—may significantly affect its thermal conductivity. While numerous theoretical studies exist, experimental data remain limited. In this work, the thermal conductivity of heavily nitrogen-doped 3C–SiC single crystals grown via the top-seeded solution growth method is measured by time-domain thermoreflectance. The results show a significant reduction (up to 30%) in thermal conductivity at nitrogen doping concentrations around 2 × 1020 cm−3. The doping concentration and distribution are investigated using secondary ion mass spectroscopy and atom probe tomography, revealing an atomic-scale uniform nitrogen distribution. Experimental results show a lower thermal conductivity reduction than previous density functional theory predictions, indicating weaker phonon–electron scattering than expected. Large-area thermal conductivity measurement and mapping reveal spatially uniform thermal conductivity in 3C–SiC at the micro-to-macroscale, emphasizing its practical utility and general high quality. These findings shed light on understanding the doping effects on thermal transport in semiconductors and support further exploration of 3C–SiC for electronics thermal management.