Thermal conductivity of boron arsenide above 2100 W per meter per Kelvin at room temperature

Abstract

Boron arsenide (BAs) single crystals had been previously reported to have thermal conductivity of 1500 W/m·K at room temperature. Now we achieved thermal conductivity above 2100 W/m·K at room temperature in BAs crystals due to lower concentration of impurities grown from purified arsenic, as evidenced by contrasting Raman spectra at sample regions with high and low thermal conductivities. We also observed a T−1.8 dependence of the thermal conductivity, suggesting a more significant contribution from four-phonon scatterings than suggested by previous theory. We found that our experimental result can be fit with a modified theoretical calculation by tuning down the three-phonon scattering for phonons in the 4–8 THz range, although current phonon transport theory cannot provide a physical explanation. Such an advance will not only attract more effort on growing BAs single crystals and studying their practical applications but also stimulate theoretical work to predict more materials with possibly even higher thermal conductivities.