Precise control of strain field for the selective formation of self-assembled InAs/GaAs quantum dots

We have investigated the alignment of self-assembled InAs quantum dots (QDs) using the strained InxGa1−xAs/GaAs superlattice system in which we can control the strain field precisely. Through the estimation of critical thickness of strained layer, an in situ alignment of quantum dots is obtained along 〈1 1 0〉 direction on the controlled strained layer. The anisotropic alignments along [1 1 0] and [1 1̄ 0] directions are closely related with the anisotropy of strain-relief for both directions, which affect the anisotropic diffusivity of indium adatoms on the strained superlattice layer. The strong alignment appears on the highly strained layer, resulting in the formation of chained quantum dots. These results indicate that aligned InAs quantum dots formed by changing the periods of strained superlattice hold promise for potential applications in nanoelectronic devices, such as single electron tunneling devices.