A. Fantini, F. Phillipp, C. Kohler, J. Porsche, and F. Scholz, Investigations of self-assembled InP-GaInP quantum dot stacks by transmission electron microscopy, Journal of Crystal Growth 244 (2002) 129-135

C. Kohler, Atomistic Simulations of Strain Distributions in Quantum Dot Nanostructures, Journal of Physics: Condensed Matter 15 (2003) 133-146

Description:

Many materials of technological importance, such as structural ceramics (e.g., SiC, Si₃N₄) or semiconductors (e.g., GaAs), consist of covalently bonded atoms. In the case of structural ceramics, these directional bonds are responsible for their high strength, high melting point, and low thermal conductivity. However, as conventional crystals, these materials are extremely brittle and therefore not suitable for technological applications since they develop cracks under external load. The plasticity required for applications can be achieved through a polycrystalline structure. The strength of the composite then is often much larger than the strength of its constituents. In this case, the interfaces between the nanometer sized grains play an important role since they deflect cracks enhancing the fracture toughness.  The subject of the present project is the investigation of such structures of interfaces using classical molecular dynamics simulations.

Pictured are surfaces of vanishing horizontal strain in a Ge/Si quantum dot system. Above the quantum dot (in between the two surfaces) the horizontal strain is tensile. Above the upper surface and below the lower surface the horizontal strain is compressive. The system size is 23 nm x 23 nm x 35 nm.

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