A STEREO-ETCHING FOR OBSERVATION OF DEFECTS IN HEAVILY Te-DOPED GaAs CRYSTAL

The defects in the heavily Te-doped GaAs crystals were observed under optical microscope using A/B etchant. It showed that the distance from the dislocation line to metallographic etched surface may be qualitatively ascertained on the basis of the etched figure on the specimen surface. Thus, to make an approach to concept of "stereo-etching" was tried and its principle was also discussed. After observation on the helicoidal dislocation and boat pit by means of "stereo-etching", it was confirmed that a boat pit is in correspondence with either one pitch of helicoidal dislocation or an individual dislocation loop.