Critical barrier thickness for the formation of InGaAs/GaAs quantum dots

Experimental evidence of strain below the quantum dots (QDs) has induced us to study the influence of very thin barrier GaAs layers on InGaAs/GaAs QDs structures. This In diffusion due to strain defines the Critical Barrier Thickness for the formation of quantum wells from three dimensional islands. A Critical Barrier Thickness of 6 nm was observed in the case of 1.8 nm In0.5Ga0.5As/GaAs QDs structures. Above this thickness stacked QDs show near perfect alignment, whilst below this thickness modulated QWs are observed. The structural behaviour is supported by photoluminescence (PL) characteristics.