Defect production in collision cascades in elemental semiconductors and fcc metals

TLDR

The study compares collision cascades in two elemental semiconductors and five fcc metals to understand how material properties influence primary defect production during ion irradiation. Full 400 eV–10 keV molecular‑dynamics simulations of collision cascades were performed on each material, comparing outcomes to assess how mass, melting temperature, strength, and crystal structure affect cascade‑induced modifications. The simulations reveal that crystal structure dominates damage production, with interstitials prevailing as point defects; semiconductors generate amorphous clusters, whereas metals largely recover, leaving only small vacancy‑rich clusters, and heavy metals occasionally form large interstitial clusters from high‑density liquid zones during recrystallization.

Abstract

A comparative molecular dynamics simulation study of collision cascades in two elemental semiconductors and five fcc metals is performed to elucidate how different material characteristics affect primary defect production during ion irradiation. By using simulations of full 400 eV-10 keV collision cascades and contrasting the results on different materials with each other, we probe the effect of the mass, melting temperature, material strength, and crystal structure on the modification of the material due to the cascade. The results show that the crystal structure has a strong effect on many aspects of damage production, while other material characteristics are of lesser overall importance. In all materials studied, isolated point defects produced by the cascade are predominantly interstitials. In semiconductors, amorphous clusters are produced in the cascade core, whereas in metals most of the crystal regenerates, leaving only small vacancy-rich clusters. Large interstitial clusters found in a few events in the heavy metals were observed to form by the isolation of a high-density liquid zone during the recrystallization phase of a cascade.