Vapor‐Flux Growth of c‐BP Single Crystals With Concurrently High Electrical Resistivity and Isotope‐Enhanced High Thermal Conductivity

ABSTRACT Cubic boron phosphide (c‐BP) is another class of high thermal conductivity material alongside cubic boron arsenide (c‐BAs) and diamond, as a promising candidate semiconductor for thermal management applications. Here, we report a new vapor‐flux growth method that enables the growth of several mm‐size crystals with significantly reduced defect densities, impurity inclusions, and achieving room temperature resistivity as high as 600 Ω cm. The resistivity value is much higher than previous reports and approaches the semi‐insulating regime, a desirable characteristic of semiconductors. Most notably, the isotope‐enriched c‐ ¹⁰ BP shows thermal conductivity values that are significantly higher than natural c‐BP and c‐ ¹¹ BP across a wide temperature range. Specifically, at room temperature the corresponding values are ≈600 W m ⁻¹ K ⁻¹ , 488 W m ⁻¹ K ⁻¹ and 540 W m ⁻¹ K ⁻¹ , respectively. This enhancement is attributed to the weaker anharmonic phonon‐phonon interaction in c‐ ¹⁰ BP compared to c‐ ¹¹ BP, as explained by first principles calculations.