LAUSR

As microelectronic devices become faster and smaller, materials with ultrahigh thermal conductivity (κ) are becoming important for new generation electronic devices. Recently, based on first-principles calculations, boron arsenide (BAs) with a zinc blende-type cubic structure was predicted to possess an unusually high κ at room temperature of over 2000 Wm K, comparable to that of diamond [1]. However, the experimentally measured κ of BAs single crystals was only 200~350 Wm K for a few years, an order of magnitude lower than the predicted value [2-3]. Although theoretical calculations [4] and x-ray photoelectron spectroscopy (XPS) studies [2,3] reveal that As vacancies (VAs), even with very low concentration, could significantly suppress κ, VAs in BAs materials has never been directly observed to date. Therefore, direct observation and identification of the intrinsic defects in BAs that suppress κ become quite urgent for growth of high-quality BAs crystals or films.