DEFECT PRODUCTION IN COLLISION CASCADES IN ELEMENTAL SEMICONDUCTORS AND FCC METALS

A comparative molecular dynamics simulation study of collision cascade s in two elemental semiconductors and five fee metals is performed to elucidate how different material characteristics affect primary defect production during ion irradiation. By using simulations of full 400 e V-10 keV collision cascades and contrasting the results on different m aterials with each other, we probe the effect of the mass, melting tem perature, 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, w hile other material characteristics are of lesser overall importance. In all materials studied, isolated point defects produced by the casca de are predominantly interstitials. In semiconductors, amorphous clust ers are produced in the cascade core, whereas in metals most of the cr ystal regenerates, leaving only small vacancy-rich clusters. Large int erstitial clusters found in a few events in the heavy metals were obse rved to form by the isolation of a high-density liquid zone during the recrystallization phase of a cascade.