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Title: Real-time observation of nanoscale topological transitions in epitaxial PbTe/CdTe heterostructures

The almost completely immiscible PbTe/CdTe heterostructure has recently become a prototype system for self-organized quantum dot formation based on solid-state phase separation. Here, we study by real-time transmission electron microscopy the topological transformations of two-dimensional PbTe-epilayers into, first, a quasi-one-dimensional percolation network and subsequently into zero-dimensional quantum dots. Finally, the dot size distribution coarsens by Ostwald ripening. The whole transformation sequence occurs during all stages in the fully coherent solid state by bulk diffusion. A model based on the numerical solution of the Cahn-Hilliard equation reproduces all relevant morphological and dynamic aspects of the experiments, demonstrating that this standard continuum approach applies to coherent solids down to nanometer dimensions. As the Cahn-Hilliard equation does not depend on atomistic details, the observed morphological transformations are general features of the model. To confirm the topological nature of the observed shape transitions, we developed a parameter-free geometric model. This, together with the Cahn-Hilliard approach, is in qualitative agreement with the experiments.
Authors:
; ; ;  [1] ; ;  [2] ;  [3] ; ;  [4]
  1. Institute of Semiconductor and Solid State Physics, Johannes Kepler University, Linz 4040 (Austria)
  2. Nanomaterials Microdevices Research Center, Osaka Institute of Technology, Asahi-ku Ohmiya, Osaka 535-8585 (Japan)
  3. Center for Surface- and Nanoanalytics (ZONA), Johannes Kepler University, Linz 4040 (Austria)
  4. Max Planck Institute of Microstructure Physics, Halle 06120 (Germany)
Publication Date:
OSTI Identifier:
22269573
Resource Type:
Journal Article
Resource Relation:
Journal Name: APL Materials; Journal Volume: 2; Journal Issue: 1; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CADMIUM TELLURIDES; EPITAXY; LEAD TELLURIDES; NUMERICAL SOLUTION; QUANTUM DOTS; SOLIDS; TRANSMISSION ELECTRON MICROSCOPY