Evidence of the role of boron in undoped GaAs grown by liquid encapsulated Czochralski

Abstract

We provide experimental evidence of electrical activity correlated with residual boron impurities and native point defects in undoped liquid-encapsulated Czochralski GaAs crystals. In Ga-rich samples containing ≥1017 cm−3 boron, an 0.073-eV acceptor level is observed in which the concentration increases with Ga and B content. An approximately quadratic increase in the concentration of the 0.073-eV defect acceptor is observed with increasing boron concentration, suggesting that a complex involving boron with an intrinsic defect (VAs, Gai, or GaAs ) is responsible for the observed acceptor behavior. No evidence of electrically active boron or boron complexes was found in semi-insulating GaAs pulled from stoichiometric or As-rich melts.