Evidence for strain in and around InAs quantum dots in GaAs from ion-channeling experiments

Strain in and around pyramidal InAs/GaAs quantum dots (QD's) fabricated by molecular-beam-epitaxy influences the density of states of the confined charge carriers. The presence of strain in QD's is required to explain their optical properties. In this paper MeV ion-channeling experiments are presented which provide evidence for the presence of strain in and around InAs QD's in GaAs. The small dimensions of the QD's (typical height 4 nm) and the presence of a wetting layer complicate the interpretation of channeling measurements, but our experiments show that extended strain fields around the QD's induce ion steering which accounts for the observed channeling behavior.