Interfacial mechanics and shear deformation of indented germanium on silicon (001) using molecular dynamics

VT Pham and TH Fang, VACUUM, 173, 109184 (2020).

DOI: 10.1016/j.vacuum.2020.109184

Molecular dynamics (MD) simulations are employed to study interfacial mechanics, shear deformation of Ge on Si(001) substrate by indentation method. A model Ge-deposited/Si and a model Ge-crystal/Si were built to study the correlation between structure, deformation behaviors, hardness, elastic modulus these two models during the indentation process. It is found that a higher loading speed results in a higher force and hardness. As increasing the indenter radius, the force increases, however the hardness almost is not affected. The force, the hardness and the elastic modulus decrease as increasing the temperature. Pile-up phenomenon almost does not appear during the indentation process. With the same indentation depth, the force and the hardness of the Ge-deposited/Si are lower than the Ge-crystal/Si. The deformation of the Ge-deposited/Si is based on shear transformation zones (STZs). After removing the load, the structure of the Ge-crystal/Si substrate has a higher recovery rate than the Ge-deposited/Si. The STZs structure in the Ge-deposited/Si is more disordered, larger free volume, higher atomic stress, and lower symmetry. The plastic deformation in the Ge- deposited/Si propagates spherically from the center of indentation, but for the Ge-crystal/Si, this type of deformation propagates along with the interface between the Ge layer and Si layer, additionally.

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