Previous studies have reported that boron arsenide (BAs) single crystals exhibit a thermal conductivity of 1500 W/m·K at room temperature.

A collaborative research team led by Professor Zhifeng Ren from the University of Houston, in partnership with researchers from Boston College, has achieved a breakthrough. By purifying arsenic raw materials to lower impurity concentrations, they have successfully grown BAs crystals with a room-temperature thermal conductivity exceeding 2100 W/m·K—potentially surpassing diamond, which has long been regarded as the best thermally conductive isotropic material. The variation in thermal conductivity across different sample regions was verified through comparative Raman spectroscopy.

Prof. Zhifeng Ren and his research group at the University of Houston and the Texas Center for Superconductivity measured the thermal conductivity by mounting the boron arsenide crystals onto a Frequency-Domain Thermoreflectance (FDTR) system.

The experiments also observed a temperature dependence of T^-1.8 for the thermal conductivity, suggesting that four-phonon scattering contributes significantly more than previously predicted by existing theories. By adjusting the three-phonon scattering parameters of phonons in the 4–8 THz frequency range, the revised theoretical calculations align well with the experimental results, although the current phonon transport theory cannot yet fully explain this phenomenon.

This breakthrough not only advances the research on the growth and application of boron arsenide single crystals but also inspires the theoretical community to explore and predict materials with even higher thermal conductivity.

Published in the journal Materials Today on October 10, this study challenges established theories and may reshape our understanding of thermally conductive materials. It could also pave the way for a new type of semiconductor material, offering superior thermal management performance for applications in smartphones, high-performance electronics, and data centers.