Synthesis and high thermal conductivity in cubic BAs and BP crystals

The zinc blende cubic BAs and BP, due to their potential ultra-high thermal conductivity ($\kappa )$ calculated through first principle approach, have attracted significant research efforts in the past few years. In order to experimentally verify the predicted high $\kappa $ values, high quality defect-free single crystal growth is needed to eliminate phonon scattering caused by defects such as deficiency, anti-site defects, voids, impurities, twin/grain boundaries. Herein, we have carried out systematical studies to: 1) find out the suitable crystal growth techniques for BAs and BP despite many challenges ; 2) investigate the growth mechanism to optimatize the crystal growth; and 3) grow large size of BAs and BP crystals up to 1.5 mm size where a high $\kappa $ up to 600 W/m/K is obtained from time-domain thermoreflectance (TDTR) measurments. The obtained $\kappa $ value is much higher than that of AlN (\textasciitilde 400 W/m/K), and is only smaller than that of C-based diamond and nanotube/graphene.