ABSTRACTWe have studied the alignment of self-assembled InAs quantum dots (QDs) grown by molecular beam epitaxy using misfit dislocations generated due to the strained InxGa1-xAs/GaAs superlattice system. Structural characteristics of aligned SAQDs have been investigated by using atomic force microscopy (AFM) and transmission electron microscopy (TEM) measurements. AFM and TEM images showed that vertical stacked InAs QD arrays were aligned along <110> direction on the controlled strained layer. The anisotropic alignments along the [110] and [110] 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. 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.
Lateral electron tunneling through single self-assembled InAs quantum dots coupled to superconducting nanogap electrodes