Investigations of structural defects by etching of GaSb grown by the liquid-encapsulated Czochralski technique

This paper reports results of an investigation of the behaviour of several etchants in revealing structural defects in Al-, Te-, Cd- and Te/Cd-doped GaSb. Etchants previously suggested for GaSb, as well as two etchants developed for GaAs and InP, were tested and modified in an attempt to establish the best conditions under which a given etchant may be used and what defects it is likely to reveal. Both the solutions consisting of H2O2-H2SO4 and 3%Br-methanol provided reproducible etch figures on dislocations, the former on the (111)Ga, (111)Sb, (100) and (110) planes, and the latter only on the (111)Ga plane. In contrast, H2O2-HC1 and HC1-HNO3-H2O did not perform satisfactorily in revealing dislocations in the analyzed samples. Using permanganate etchant, it was possible to observe growth striations only in the n-type GaSb. The CrO3-HF solution revealed growth striations on both the p-type and the n-type GaSb as well as defects formed due to constitutional supercooling. A new etchant, based on ceric sulfate, was developed to delineate growth striations along the Te-doped GaSb crystals.