Molecular Dynamics Simulation of Nanostructure Formation in Amorphous SiO2 by High-Energy Irradiation

S Otsuka and Y Sasajima and N Ishikawa, ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY, 14, 124003 (2025).

DOI: 10.1149/2162-8777/ae27ff

High-energy ion beam irradiation on amorphous SiO2 was simulated using the molecular dynamics method. Three types of specimens were prepared: bulk specimens without a free surface, specimens with a free surface, and thin film specimens. Amorphous SiO2 was created by heating alpha- quartz single crystal above melting point and then cooling it to room temperature. A cylindrical region with a diameter of 3.0 nm was set at the center of the prepared specimens, and high thermal energy was applied to this region. Atomic motion was calculated using molecular dynamics methods with a large-scale atom/molecule parallel simulator. Vashishta potential was used for interatomic interaction. For bulk specimens without a free surface, it was found that the density at the center of the irradiation region decreased as the irradiation energy increased. For the specimens with a free surface, crater-like holes were generated on the surface due to irradiation. For thin film specimens, the size of the nano-holes increased as the irradiation energy increased. In all amorphous SiO2 specimens, the energy required to produce disordered region comparable to those observed in previous simulations on crystalline SiO2 was same.

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