Fabrication of lateral InAs quantum-dot-molecules on InGaAs square-like nanohole templates by 2-step growth technique using molecular beam epitaxy (MBE)

We have demonstrated the fabrication of lateral InAs quantum dot molecules (QDMs) on InGaAs square-like nanohole templates by 2-step growth technique using solid-source molecular beam epitaxy (MBE). In this work, the first step of fabrication process is droplet epitaxial (DE) growth to form the InGaAs square-like nanoholes at low temperature. Then, the substrate was ramped up to high temperature with a constant rate. At this stage, the square-like nanoholes transform into nanomounds (NMs). Finally, the lateral InAs QDMs were grown on the InGaAs NMs via Stranski-Krastanow (SK) technique. The result of this work, the QD formation mostly appears at the corner of the nanomound or deformed square-like nanohole since the corner has high compressive-strain field.