Molecular Dynamics Study of Alumina Nanoparticles' Effects on Silicon Bicrystal Amorphization at Varying Temperatures and External Shear Stresses

A Sabetghadam-Isfahani and M Silani and M Javanbakht and MM Aghdam, IRANIAN JOURNAL OF CHEMISTRY & CHEMICAL ENGINEERING-INTERNATIONAL ENGLISH EDITION, 44 (2025).

DOI: 10.30492/ijcce.2025.2056507.7054

This study investigates the effects of alumina nanoparticles on the amorphization process of silicon bi-crystals using molecular dynamics simulations. The simulations, conducted with the LAMMPS package, model a bi-crystal system containing 1620 atoms within a 129x180x7.5 & Aring;3 box, employing the TERSOFF potential for silicon and the Lennard-Jones potential for interactions between silicon and alumina nanoparticles. The simulation process consists of two stages: an equilibrium phase at temperatures ranging from 200 to 600 K for 1 ns, followed by an amorphization phase under external shear stresses from 1.55 to 2.50 GPa for another 1 ns. Key findings include the achievement of equilibrium after 1 ns at 300 K, with potential energy and mean atomic stress converging to-2.89 eV and 47.83 MPa, respectively. Amorphization is induced by shear stress, with the amorphization length increasing from 5.26 & Aring; at 300 K and 1.55 GPa to 5.98 & Aring; at 600 K and 2.50 GPa. Alumina nanoparticles serve as nucleation sites, significantly promoting the amorphization process by enhancing dislocation density and structural disorder. These results indicate that nanoparticles provide a more effective means of controlling amorphization compared to adjustments in temperature and shear stress, with potential applications in semiconductor device fabrication and solar cell manufacturing. The presence of nano-alumina slows the progression of the amorphization process. Consequently, under identical conditions including temperature, applied external shear stress, and time the rate of dislocation formation decreases, resulting in approximately 20% fewer dislocations overall. Additionally, the yielding stress threshold of a single crystal has increased from 8.2 to 12.8 GPa, indicating a significant enhancement in the material's resistance to deformation under applied stress.

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