Divacancy production in low-temperature electron-irradiated silicon

We report deep-level transient spectroscopy studies on the divacancy formation in electron-bombarded silicon at 80 K. Samples irradiated to a dose D₁=3.5×{}10¹⁶ e^-/cm² and using a beam current i₁=0.33 {μ}A/cm² give rise to an unstable peak seen to anneal out rapidly below 150 K. The center responsible for this peak seems to act as an intermediate step in the formation of at least a fraction of the neutral divacancies. Under conditions of irradiation with dose D₂=1.7×{}10¹⁶ e^-/cm² and beam current i₂=0.20 {μ}A/cm² neither the intermediate defect nor the neutral divacancy signal appears in the spectrum. Instead, a divacancy-related EV+0.13 eV level emerged. An interpretation of the data is attempted in terms of a model postulating charge-state-dependent metastable structures.