From compact point defects to extended structures in silicon

First-principles studies of the formation and dynamics of silicon interstitial-clusters suggest a possible growth mechanism of silicon interstitial-chains as seen in macroscopic 311 planar defects. The relative populations of the three lowest-energy silicon tri-interstitials equilibrate within a few microseconds. Unfortunately, the tri-interstitial chain is unstable, quickly decaying to the ground-state interstitial. However, the four-interstitial chain with escape barriers of 0.54 eV is relatively stable and can be formed by exothermic capture of an interstitial by the ground-state tri-interstitial. This first successful step seems capable of growing longer chains. If one chain eases the formation of a second parallel chain, this may start the process of forming 311 planar defects.