Theoretical and experimental studies on post-growth thermal annealing of self-assembled InAs/GaAs quantum dots

Self-assembled InAs/GaAs quantum dots (QDs) are the potential candidates for the fabrication of high performance lasers and detectors for optical communication. The main focus of the researchers is to extend the ground state (GS) photoluminescence (PL) emission wavelength towards the high bit rate telecommunication window of 1.3-1.55µm as well as suppress the blueshift of the GS PL peak out of this range at high temperature post-growth annealing. This is in requirement of thermally stable devices which requires strict tolerance on operating wavelength. In view of this, two types of QD heterostructures were grown. The first one is a bilayer QD structure with larger monolayer coverage of dots of 3.2 ML. The second one is a ten layer stacked QD heterostructure with a combination capping of InAlGaAs/GaAs layer. The experimental studies and characterization of these two types of QDs will be described. All these experimental studies addresses the necessity of a design tool which can provide a useful solution to engineer the optical emission of QD materials subjected to thermal annealing. Hence, we have developed theoretical modelling and simulation which predicts the compositional and band-structural changes of the annealed QDs which are also in very good agreement with our experimental investigations. The results will be discussed.