Manipulations of densities and sizes during self-assembling quantum dots in MOVPE

Abstract

Quantum dot structures in the form of coherent 3-dimensional islands can be grown in-situ by "self-assembling". The specifics of self assembling is that strain in a critically thick 2-dimensional wetting layer acts as the driving force for a transition towards an energetically favoured 2-dimensional (wetting)+ 3-dimensional (island) Stranski-Krastanow morphology. The initiation mechanism of the 2D-3D transition is a nucleation step, followed by growth and reorganization of material (redistribution of material from the wetting layer, ripening processes). As a consequence, for a given misfit between substrate and epilayer, densities and sizes of self-assembled 3D islands are mostly affected by the actual deposition conditions. In the following we will show to which extent densities and sizes of 3D islands deliberately can be manipulated by varying the deposition parameters Q (deposited amount), T (deposition temperature) and R (deposition rate). The chosen materials system for