Trushin, O. ; Maras, E. ; Stukowski, A. ; Granato, E. ; Ying, S. C. ; Jónsson, H. ; Ala-Nissila, T. (2016)
Minimum energy path for the nucleation of misfit dislocations in Ge/Si(0 0 1) heteroepitaxy.
In: Modelling and Simulation in Materials Science and Engineering, 24 (3)
doi: 10.1088/0965-0393/24/3/035007
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

A possible mechanism for the formation of a 90° misfit dislocation at the Ge/Si(0 0 1) interface through homogeneous nucleation is identified from atomic scale calculations where a minimum energy path connecting the coherent epitaxial state and a final state with a 90° misfit dislocation is found using the nudged elastic band method. The initial path is generated using a repulsive bias activation procedure in a model system including 75 000 atoms. The energy along the path exhibits two maxima in the energy. The first maximum occurs as a 60° dislocation nucleates. The intermediate minimum corresponds to an extended 60° dislocation. The subsequent energy maximum occurs as a second 60° dislocation nucleates in a complementary, mirror glide plane, simultaneously starting from the surface and from the first 60° dislocation. The activation energy of the nucleation of the second dislocation is 30% lower than that of the first one showing that the formation of the second 60° dislocation is aided by the presence of the first one. The simulations represent a step towards unraveling the formation mechanism of 90° dislocations, an important issue in the design of growth procedures for strain released Ge overlayers on Si(1 0 0) surfaces, and more generally illustrate an approach that can be used to gain insight into the mechanism of complex nucleation paths of extended defects in solids.

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