X-ray Characterization of Defect Structure in LEC Annealed GaAs Crystals

Wafers of commercially available semi-insulating (SI) Czochralski-grown GaAs crystals have been annealed at temperatures near the melting point (> 1100 °C) both for relatively short and long time and then rapidly quenched into cold water. Heat-treated crystals have been investigated by X-ray transmission diffraction topography. Cellular structure pattern of the as-grown sample is replaced by images of precipitates spread out over whole sample. This suggests that the excess arsenic condenses as As precipitates with nucleation sites not correlated with cell walls.