The comprehensive molecular dynamics study of amorphization process evolution inside ∑3, ∑9, and ∑19 structures of nanometric silicon Bi-crystal

Abstract

This study investigates the physical stability and atomic amorphization of silicon bi-crystals through Molecular Dynamics simulations. Initially, the equilibrium phase of silicon bi-crystals with ∑3, ∑9, and ∑19 structures was established. Subsequently, amorphization of the equilibrated samples was simulated by embedding external shear stresses. The findings indicate that elevated temperatures and increased external shear stresses lead to an effective atomic amorphization and an increase in the dislocation velocity, characterized by a decrease in attraction forces and alterations in atomic distribution. Among the three structures, the ∑19 structure exhibits the most significant atomic evolution, suggesting a higher propensity for the amorphization under identical conditions. The study finds that all the modeled samples maintain physical stability across the working temperatures ranging from 100 to 600 K. The study also explores the impact of varying shear stress values on the atomic amorphization. Increasing the applied shear stress increases both the maximum stress and dislocation stress, with the ∑19 structure being the most affected. At 600 K, the maximum atomic stress required to initiate the amorphization in the ∑19, ∑9, and ∑3 structures is found to be 9.41, 10.02, and 10.39 GPa, respectively, corresponding to the external shear stresses of 1.36, 160, and 1.55 GPa, respectively. The study concludes that both working temperature and applied external shear stress are critical factors in the amorphization of silicon bi-crystals.