Two methods of anodically etching n-GaAs have been investigated. Subsequently they have been used to detect crystallographic defects present in bulk-grown, single crystal material. The first method provides topographical featuring of the semiconductor anode. The selective discrimination of defects achieved via this controlled electrochemical technique is superior to that obtainable from standard chemical etchants. The second dissolution regime, in which an interracial oxide layer is continuously present, permits smooth, featureless removal of material. Thus a simple two-stage anodization procedure has allowed the damage characteristic of the Beilby layer to be probed. Thereafter, a total, smooth removal of this damaged surface layer permits identification of bulk crystallographic defects---dislocation structures well known in GaAs require the dissolution of only 0.5 ~m. Analysis of the semiconductor electrode condition in the electrolytes used for etching has yielded model results. Such analyses have enabled the relationship between the electrical properties of the defected GaAs and the individual topography of the defects as etched to be explored.

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