Ring defect of GaAs studied

Common defects in GaAs are dislocations, stacking faults, and precipitates. Etching with molten KOH often reveals the dislocation pits, and the number of dislocation pits is generally used as an indicator of the defect density of the single crystal. Recently, circular defects were observed in chemically etched Si-doped GaAs single crystals grown in a horizontal boat. Some of these circular defects have an indented central part and resemble the shape of lunar mountains. They are ring defects. The detection method of ring defects and the results of electron probe analysis are described in detail.