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 cha rge carriers. The presence of strain in QD's is required to explain their o ptical properties. In this paper MeV ion-channeling experiments are present ed 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 p resence of a wetting layer complicate the interpretation of channeling meas urements, but our experiments show that extended strain fields around the Q D's induce ion steering which accounts for the observed channeling behavior .