Evolution of boron-interstitial clusters in crystalline Si studied by transmission electron microscopy

The thermal evolution of large boron-interstitials clusters (BICs) in crystalline Si has been studied by transmission electron microscopy (TEM). After ion implantation (⁠$20keV$ and $1×1014Si∕cm2$⁠) and annealing (⁠$815°C$ and $5min$⁠), large clusters $(6–8nm)$ have been observed in correspondence of a narrow, highly doped Si:B layer $(2×1020B∕cm3)$⁠. Under prolonged annealing, such clusters dissolve, progressively shrinking their mean size below the TEM detection limit. The time evolution of such a BIC shrinking is fully compatible with the slow path dissolution kinetics recently published. These data suggest the identification of the slow dissolving BICs with the large observed clusters.