Annealing kinetics of vacancy-related defects in low-dose MeV self-ion-implanted n-type silicon

Silicon samples of n-type have been implanted at room temperature with 5.6-MeV (formula presented) ions to a dose of (formula presented) and then annealed at temperatures from 100 to 380 °C. Both isothermal and isochronal treatments were performed and the annealing kinetics of the prominent divacancy (formula presented) and vacancy-oxygen (VO) centers were studied in detail using deep-level transient spectroscopy. The decrease of (formula presented) centers exhibits first-order kinetics in both Czochralski-grown (CZ) and float-zone (FZ) samples, and the data provide strong evidence for a process involving migration of (formula presented) and subsequent annihilation at trapping centers. The migration energy extracted for (formula presented) is ∼1.3 eV and from the shape of the concentration versus depth profiles, an effective diffusion length ⩽0.1 μm is obtained. The VO center displays a more complex annealing behavior where interaction with mobile hydrogen (H) plays a key role through the formation of VOH and (formula presented) centers. Another contribution is migration of VO and trapping by interstitial oxygen atoms in the silicon lattice, giving rise to vacancy-dioxygen pairs. An activation energy of ∼1.8 eV is deduced for the migration of VO, in close resemblance with results from previous studies using electron-irradiated samples. A model for the annealing of VO, involving only three reactions, is put forward and shown to yield a close quantitative agreement with the experimental data for both CZ and FZ samples over the whole temperature range studied.