Combined used of EBIC and DSL photoetching for the quantitative assessment of defect properties in LEC GaAs

The influence of the surface depletion region width and hole diffusion length on the formation of etch features by DSL. photoetching in n-type GaAs has been studied by the combined use of DSL and EBIC. The formation of etch grooves at growth striations is mainly affected by the properties of the surface depletion region, in particular its width. Etch hillocks at impurity atmospheres, even without any associated dislocation, are mainly due to the very short hole diffusion length at these defects which prevents hole diffusion to the surface and the consequent GaAs dissolution. Narrowing of the surface depletion region, due to an increased density of dopant in the impurity atmospheres. may also contribute to hillock formation.