Patterned formation of InAs QDs for single-electron device applications

The selective growth of self-assembled InAs quantum dots (SAQDs) on semi-insulating GaAs (100) substrates with sub-micron tungsten patterns has been studied. We fabricate sub-micron tungsten patterns on GaAs substrates before we grow SAQDs. Quantum dots preferentially nucleate between the active region of the tungsten patterns. Three or four SAQDs are clearly observed between tungsten electrodes, which suggests that the formation of single electron device structure is possible by using our technique. In addition, we notice a clear depletion of QDs along the edge of the tungsten electrodes. The width of this QD-free zone is roughly 0.4 μm.