MOLECULAR-DYNAMICS SIMULATION OF LOW-ENERGY COLLISION CASCADES AND ATOMIC MIXING IN SILICON

We investigate atomic relocation processes in silicon at OK, initiated by an internal 100 eV silicon recoil. The molecular dynamics code MOD YSEM is used, based on a Tersoff potential for silicon. A fitting proc edure was used far the generation of a potential valid over the whole energy range of interest. The contribution of the collisional, spontan eous relaxation and thermalization stages to the atomic relocation pro cess are discussed. A threshold distance for the definition of relocat ed atoms is determined, which separates atomic displacements into stab le and unstable (or transient) groups. The atomic mixing process is qu antified in terms of the first and second spatial moments over the rel ocation cross-section. These moments depend on the criterion used to d efine a relocated Si atom, with short-distance thermal-like atomic dis placements, which appear during the thermalization stage, dominating t he values of the spatial moments. However, the moments of the relocati on cross-section calculated by considering only the stable displacemen ts are generated mainly by collisional atomic relocations.