Real-time observation of nanoscale topological transitions in epitaxial PbTe/CdTe heterostructures
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University, Linz 4040 (Austria)
- Nanomaterials Microdevices Research Center, Osaka Institute of Technology, Asahi-ku Ohmiya, Osaka 535-8585 (Japan)
- Center for Surface- and Nanoanalytics (ZONA), Johannes Kepler University, Linz 4040 (Austria)
- Max Planck Institute of Microstructure Physics, Halle 06120 (Germany)
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.
- OSTI ID:
- 22269573
- Journal Information:
- APL Materials, Vol. 2, Issue 1; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 2166-532X
- Country of Publication:
- United States
- Language:
- English
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