Silicon self-interstitial migration: Multiple paths and charge states

Total energy calculations performed to study the migration of silicon self-interstitials reveal a great complexity of migration paths. ${\mathrm{Si}}^{\mathrm{}(++)\mathrm{}}$ and ${\mathrm{Si}}^{\mathrm{}\left(0\right)\mathrm{}}$ each migrate along more than one path and different paths from each other. Some paths involve interchange with bulk atoms. Electron-assisted transport occurs for the ${\mathrm{Si}}^{\mathrm{}(++)\mathrm{}}$ stable tetrahedral site in all directions. ${\mathrm{Si}}^{\mathrm{}\left(0\right)\mathrm{}}$ has several almost-degenerate lowest-energy configurations. The lowest is the "exchange" configuration which also has the possibility of being negative (${\mathrm{Si}}^{\mathrm{}(-)\mathrm{}}$).