Molecular-dynamics simulations of solid-phase epitaxy of Si: Growth mechanisms

Crystal-growth processes of Si during solid phase epitaxy (SPE) in the [001 ] direction have been investigated based on molecular-dynamics (MD) simulat ions using the Tersoff potential. A tetragonal cell including an amorphous/ crystalline (a/c) Si interface composed of up to 4096 atoms was taken as th e starting system. From the Arrhenius plot of the growth rates obtained by MD simulations, we have found that the activation energy of SPE at lower te mperatures is in good agreement with the experimental value (approximate to 2.7 eV), while it becomes lower at higher temperatures. This can be attrib uted to the difference in the a/c interface structure and SPE mechanism. In the low-temperature region, the ale interface is essentially (001) and the rate-limiting step is two-dimensional nucleation on the (001) ale interfac e. On the other hand, the ale interface is predominantly composed of {111} facets in the high-temperature region and the rate-limiting step is presuma bly a diffusion process of Si to be trapped at the kink sites associated wi th these facets.