Analysis of peculiar structural defects created in GaAs by diffusion of copper

Abstract

High spatial resolution and high-sensitivity techniques, such as DSL etching, AFM and TEM, have been used to analyse peculiar structural defects created in GaAs by Cu diffusion. They consist of (1) entangled grown-in dislocations surrounded by dislocation loops, (2) clusters of dislocation loops and (3) {0 0 1} complex planar defects revealed as square-like etch features on the (0 0 1) etch surface or as 〈1 0 0〉 linear etch features when these planar defects lie in the (1 0 0) or (0 1 0) planes perpendicular to the sample surface. The 〈1 0 0〉 linear defects are due to straight dislocation segments decorated by precipitates whereas the (0 0 1) defects are ascribed to loops from the clusters of type (2) that have selectively grown to a size much larger than the other ones. All these defects are surrounded by regions of enhanced etch rate. Their formation is ascribed to the interaction between point defects created during Cu diffusion that presumably occurs by the kick-out mechanism, whereby Cu Ga and Ga interstitials are formed.