Letter abstract

Nature Nanotechnology 4, 835 - 838 (2009)
Published online: 27 September 2009 | doi:10.1038/nnano.2009.271

Subject Categories: Nanoparticles | Surface patterning and imaging | Synthesis and processing

Atomic-scale mapping of quantum dots formed by droplet epitaxy

Divine P. Kumah1, Sergey Shusterman2, Yossi Paltiel3, Yizhak Yacoby4 & Roy Clarke1

Quantum dots (QDs) have applications in optoelectronic devices1, 2, quantum information processing3, 4 and energy harvesting5, 6. Although the droplet epitaxy fabrication method7, 8, 9 allows for a wide range of material combinations to be used, little is known about the growth mechanisms involved10, 11. Here we apply direct X-ray methods12, 13, 14 to derive sub-ångström resolution maps of QDs crystallized from indium droplets exposed to antimony, as well as their interface with a GaAs (100) substrate. We find that the QDs form coherently15 and extend a few unit cells below the substrate surface. This facilitates a droplet–substrate exchange of atoms, resulting in core–shell structures that contain a surprisingly small amount of In. The work provides the first atomic-scale mapping of the interface between epitaxial QDs and a substrate, and establishes the usefulness of X-ray phasing techniques for this and similar systems.

  1. Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109, USA
  2. Solid State Physics, Electro-Optics Division, Soreq NRC, Yavne, 81800 Israel
  3. Applied Physics Department and the Center for Nanoscience and Nanotechnology, Hebrew University, Jerusalem 91904, Israel
  4. Racah Institute of Physics, Hebrew University, Jerusalem 91904, Israel

Correspondence to: Roy Clarke1 e-mail: royc@umich.edu


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