Pile-up and heat effect on the mechanical response of SiGe on Si(001) substrate during nanoscratching and nanoindentation using molecular dynamics

VT Pham and TH Fang, COMPUTATIONAL MATERIALS SCIENCE, 174, 109465 (2020).

DOI: 10.1016/j.commatsci.2019.109465

Molecular dynamics (MD) simulations are performed to study the mechanical behavior of SiGe thin film during nanoindentation and nanoscratching processes. The MD simulations of deposition and annealing process are conducted to create the Si80Ge20 thin film deposited on Si(0 0 1) substrate. MD simulations of nanoindentation and nanoscratching processes are carried out to study the influence of the temperature on deformation behaviors and mechanical properties of this material. Moreover, the influences of the scratching depth, tool velocity, and temperature on the deformation behavior during nanoscratching process are also surveyed. It is found that the elastic and plastic deformations occur and the shear transformation zones (STZs) are independently developed in the contact region. The force, hardness, and Young's modulus of the Si80Ge20 thin film deposited on the Si substrate decrease as increasing the temperature during the indentation process. The pile- up, friction force, and normal force grow as increasing the scratching depth. As increasing the scratching speed, the pile-up increase while the normal force and the friction force reduce due to the effect of heat and strain rate are more efficient than the effect of the pile-up. As increasing the temperature, the height of pile-up increases while the normal force and the friction force decrease as a result of a higher temperature leads to softening the workpiece because the thermal expansion causes a reduction of the bonding strength of atoms.

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