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

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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.