Seeded Growth and Characterization of Boron Arsenide Single Crystals with High Thermal Conductivity*

With the rapid miniaturization of modern microelectronic devices, the need for materials with high thermal conductivity for passive cooling is continuously growing. Recently, zinc-blende boron arsenide (BAs) has emerged with a surprisingly high lattice thermal conductivity of over 2000 W m^-1 K^-1 at room temperature as predicted by first-principles calculations, which makes it a potential competitor for diamond that holds the highest thermal conductivity to date. However, due to the extremely challenging difficulties in the preparation of high quality single crystals, experimental demonstration has not been obtained. Here, we report synthesis of BAs crystals (0.4 ~ 0.6 mm) via a seeded chemical vapor transport method. The measured thermal conductivity, at least 341 W m^-1 K^-1 at room temperature, is not as high as predicted, but is highest among reported values and comparable to that of popular high thermal conductivity materials like copper and aluminum nitride. Further improvement seems very possible along this direction.