Anomalous reduction of lattice parameter by residual impurity boron in undoped Czochralski-grown GaAs

An anomalous reduction of lattice parameter is observed for undoped semi-insulating liquid encapsulated Czochralski-grown GaAs by precision lattice parameter measurements with the use of the bond method. The anomalous reduction is though to be due to the incorporation of residual boron from the B2O3 encapsulant. The reduction rate is about 2 times larger than the predicted rate for the boron concentration derived from Vegard’s law. Possible defect models for this phenomenon are discussed.