Defect etching of GaAs on Si

A series of repeated etches of an identical area of bulk GaAs has been used to demonstrate the unusual action of the Wright etch. Emergent dislocations initially become etch pits, but at the same time a network of trails similar to those seen after A/B etching is also produced. Detailed TEM examinations of Wright etched GaAs epitaxial layers on Si have been examined as plan-view specimens by back-thinning. They demonstrate that the Wright etch can indeed produce etch pits at dislocation sites. The results also illustrate the problems involved in making direct comparisons between optical and TEM dislocation density determinations. Nevertheless, the author believes that the results will show that progress has been made towards this goal