Void formation and inhibition of layer intermixing in ion-impIanted GaAs/AlGaAs superlattices

Voids have been found in the near-surface region of GaAs/AlGaAs superlattices in a transmission electron microscopy study. The superlattices were Si- or Al-implanted and subsequently either furnace or rapid thermally annealed. Concurrent with the presence of voids is an inhibition of superlattice layer intermixing enhancement in the near-surface region. This inhibition does not occur in the deeper region of the samples where voids are not found. The voids can form via condensation of the Ga and As vacancies produced by the implantation process. We suggest that voids can depress dopant activation, suppress dopant diffusion, and inhibit the superlattice layer intermixing enhancement.