Dislocation-induced changes in quantum dots: Step alignment and radiative emission

Abstract

A transition between two types of step alignment was observed in a multilayered InGaAs/GaAs quantum-dot (QD) structure. A change to larger QD sizes in smaller concentrations occurred after formation of a dislocation array. Cathodoluminescence (CL) spectra show a bimodal peak with lower energy peak enhancement when probing at lower e-beam energies. The two peaks separate as a result of QD interdiffusion. CL imaging and cross-sectional transmission electron microscopy showed contrast from a dislocation array formed at the interface between GaAs and the first InGaAs QD layer. Strong QD emission in the near infrared (800–1100 nm) was obtained despite the presence of dislocations.