The effects of radiation damage and impurities on void dynamics in silicon

Transmission electron microscopy (TEM) has been used to study the effects of implanted oxygen or carbon on the dynamics of cavity growth in silicon. The cavities are produced by implantation with helium ions followed by annealing to convert small He-filled bubbles into large empty voids. We have also investigated the effects of self-ion damage on cavity growth. Both impurities and self-ion damage can significantly inhibit void growth. In addition, hot stage TEM has been used to elucidate the processes responsible for cavity growth in an attempt to understand the way in which both impurities and radiation damage are able to modify these processes. Cavity growth is seen to be due to Ostwald ripening and coalescence in the early stages with some sporadic, rapid motion of large bubbles leading to coalescence at higher temperatures. Our research indicates that void dynamics in silicon are quite different from those in metallic systems.