Amorphous silicon under mechanical shear deformations: shear velocity and temperature effects

TL;DR

This study uses molecular dynamics simulations to explore how shear velocity and temperature influence the structural defects and deformation behavior of amorphous silicon, revealing complex dependencies related to energy landscapes.

Contribution

It provides new insights into the combined effects of shear velocity and temperature on amorphous silicon's structural response during deformation.

Findings

Higher shear velocity increases internal strain and defect formation.

Increasing temperature mitigates deformation effects and spreads defects.

Defect distribution depends on temperature and shear velocity, influenced by energy landscape structure.

Abstract

Mechanical shear deformations lead, in some cases, to effects similar to those resulting from ion irradiation. Here we characterize the effects of shear velocity and temperature on amorphous silicon (\aSi) modelled using classical molecular dynamics simulations based on the empirical Environment Dependent Inter-atomic Potential (EDIP). With increasing shear velocity at low temperature, we find a systematic increase in the internal strain leading to the rapid appearance of structural defects (5-fold coordinated atoms). The impacts of externally applied strain can be almost fully compensated by increasing the temperature, allowing the system to respond more rapidly to the deformation. In particular, we find opposite power-law relations between the temperature and the shear velocity and the deformation energy. The spatial distribution of defects is also found to strongly depend on temperature and strain velocity. For low temperature or high shear velocity, defects are concentrated in a few atomic layers near the center of the cell while, with increasing temperature or decreasing shear velocity, they spread slowly throughout the full simulation cell. This complex behavior can be related to the structure of the energy landscape and the existence of a continuous energy-barrier distribution.