Highly luminescent nanocrystal quantum dots fabricated by lattice-type mismatched epitaxy |
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Institution: | 1. Institut für Halbleiter und Festkörperphysik, Johannes Kepler Universität, Altenbergerstraße 69, 4040 Linz, Austria;2. Osaka Institute of Technology, Asahi-ku Ohmiya, Osaka 535-8585, Japan;3. Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany;1. Institute of Semiconductor and Solid State Physics, Johannes Kepler Universität, A 4040 Linz, Austria;2. Institute of Semiconductor and Solid State Physics, Johannes Kepler Universität, A 4040 Linz, Austria;3. Institute of Physics, Montanuniversität, A 8700 Leoben, Austria;1. College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China;2. Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, China;1. Department of Mathematics, The University of British Columbia, Vancouver, B.C. V6T1Z2, Canada;2. Department of Mathematics, University of Oregon, Eugene, OR 97403, USA;1. Department of Surgery, Division of Hepatobiliary and Pancreatic Surgery, Asklepios Hospital Barmbek, Hamburg, Germany;2. Department of General and Visceral Surgery, St. Josef''s-Hospital Wiesbaden, Wiesbaden, Germany;3. Semmelweis University, Asklepios Campus Hamburg, Hamburg, Germany;4. Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary;5. Institute of Medical Biometry and Epidemiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany;6. Institute for Hematopathology Hamburg, Hamburg, Germany;7. Department of Radiology and Neuroradiology, Asklepios Hospital Barmbek, Hamburg, Germany;8. Department of Anaesthesiology and Surgical Intensive Care, Asklepios Hospital Barmbek, Hamburg, Germany |
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Abstract: | Lattice-type mismatched heteroepitaxy is demonstrated as a novel concept for the fabrication of almost ideal, highly luminescent nanocrystal quantum dots that are coherently embedded in a single-crystalline matrix. In this approach, the formation of quantum dots is induced by transformation of a metastable epitaxial 2D quantum well into an array of isolated nanocrystals with-highly symmetric shape. This process is driven by the lattice-type mismatch between the constituent materials and the resulting miscibility gap. The investigated PbTe/CdTe heterosystem has a model character because it combines two compounds with different cubic lattice types but almost identical lattice constants. The obtained epitaxial nanocrystals exhibit outstanding properties such as a well-defined symmetric shape, the absence of strain, intermixing and a wetting layer, which is in contrast to the conventional Stranski–Krastanow quantum dots. The small-rhomboedric-cubo-octahedron PbTe/CdTe nanocrystals on GaAs substrates display intense room temperature mid-infrared luminescence as is crucial for device applications. Ab initio density functional theory is used to clarify the interface structure, indicating that the covalent and ionic bonding character of CdTe and PbTe is maintained across the interface. |
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