Abstract
The effects of different growth conditions on microdefect generation in dislocation-free liquid-encapsulated Czochralski GaAs crystals are investigated using KOH etching technique and infrared light scattering tomography. It is found that microdefects are detected as micropits by KOH etching and as scatterers by infrared light scattering tomography, but are not detected by transmission electron microscopy. It is also found that the formation of these microdefects begins at below 1000 °C during the cooling process of the growth and strongly depends on the cooling rate. Other findings—melt composition and impurities (In,B), and the existence of denuded zones around dislocations—have led the authors to conclude that the microdefects are microprecipitates of excess arsenic atoms.