Behavior of defects in dual-implanted AlGaAs superlattices

Abstract The behavior of GaAs AlAs superlattices implanted with Ge and Be has been studied. As-implanted specimens showed the presence of microtwins and strain contrast. These arise due to the effect of dynamic annealing on the high concentrations of self-interstitials and of implanted atoms present in the superlattice. Dislocation loops observed in annealed samples were present on {111} or {110} planes, these being the low-energy planes in GaAs. Co-implanted samples showed a difference in behavior of damage from singly implanted samples. The difference is explained in terms of an interaction between point defects created by one implant with dopant atoms of the other implant. Voids were seen in near-surface layers of co-implanted superlattices. The origin of the voids is explained in terms of coalescence of vacancies that result from the implant.