Finite element analysis of stress and strain distributions in InAs/GaAs quantum dots

In this paper, we perform systematic calculations of the stress and straindistributions in InAs/GaAs truncated pyramidal quantum dots (QDs) withdifferent wetting layer (WL) thickness, using the finite element method (FEM).The stresses and strains are concentrated at the boundaries of the WL andQDs, are reduced gradually from the boundaries to the interior, and tend toa uniform state for the positions away from the boundaries. The maximalstrain energy density occurs at the vicinity of the interface between the WLand the substrate. The stresses, strains and released strain energy arereduced gradually with increasing WL thickness. The above results show thata critical WL thickness may exist, and the stress and strain distributionscan make the growth of QDs a growth of strained three-dimensional islandwhen the WL thickness is above the critical value, and FEM can be applied toinvestigate such nanosystems, QDs, and the relevant results are supported bythe experiments.