Alignment of InAs quantum dots on a controllable strain-relaxed substrate using an InAs/GaAs superlattice

We fabricated InAs self-assembled quantum dots on a strained layer using molecular beam epitaxy. The controllable strained layer consisted of an InAs/GaAs superlattice and a GaAs spacer layer on a GaAs (001) substrate. We formed two-dimensional arrays of quantum dots along the 〈110〉 directions on the partially strain-relaxed layer that is formed using the superlattice system. The increase in the thickness of the partially strain-relaxed layer resulted in stronger alignment of the quantum dots. The aligned quantum dots are applicable to quantum devices, because they confine carriers well, in spite of the existence of dislocation networks. Strongly aligned quantum dots have a lower carrier transition energy because of their larger size and increased relaxation.