Elemental diffusion during the droplet epitaxy growth of In(Ga)As/GaAs(001) quantum dots by metal-organic chemical vapor deposition

Droplet epitaxy is an important method to produce epitaxial semiconductor quantum dots (QDs). Droplet epitaxy of III-V QDs comprises group III elemental droplet deposition and the droplet crystallization through the introduction of group V elements. Here, we report that, in the droplet epitaxy of InAs/GaAs(001) QDs using metal-organic chemical vapor deposition, significant elemental diffusion from the substrate to In droplets occurs, resulting in the formation of In(Ga)As crystals, before As flux is provided. The supply of As flux suppresses the further elemental diffusion from the substrate and promotes surface migration, leading to large island formation with a low island density.The authors are grateful for the scientific and technical support from the Australian Microscopy and Microanalysis Research Facility node at the University of Sydney. We thank the Australian National Fabrication Facility for providing access to growth facilities used in this work. This research was financially supported by the Australian Research Council