Annealing of the divacancy-oxygen and vacancy-oxygen complexes in silicon

After low dose electron irradiation, annealing kinetics of divacancy-oxygen (V₂O) and vacancy-oxygen (VO) complexes in carbon-lean n-type magnetic Czochralski (MCZ) and diffusion-oxygenated float-zone (DOFZ) Si samples has been studied in detail. The samples were of n type with a phosphorus doping concentration in the 10¹²0.3em0excm^-3 range, and the analysis was conducted by means of deep-level transient spectroscopy (DLTS). An exponential decrease in the V₂O concentration with time during isothermal annealing at temperatures in the range 275--3550.2em0ex^∘C has been observed. The activation energy for the V₂O annealing is found to be 2.02±0.120.3em0exeV, with a preexponential factor in the 10¹³0.3em0exs^-1 range, which strongly suggests that dissociation of V₂O is the dominating mechanism. The binding energy of the vacancy to the V₂O complex has been estimated as ~1.70.3em0exeV. An increase in the VO concentration is observed in the initial phase of the V₂O annealing, which is supportive of V₂O dissociation through the reaction V₂O→VO+V. After the initial increase, a close to first order decrease in the VO concentration is observed, consistent with that VO mainly anneals by migration and trapping at oxygen interstitial sites, similarly to what has been reported in previous high-dose studies using infrared spectroscopy. The vacancy-oxygen-hydrogen complex (VOH) is formed after long time annealing. The formation of VOH is followed by a decrease at the same rate as VO, and it is suggested that VOH dissociates (VOH→VO+H). The experimental data have been compared with kinetic simulations and show good agreement with a model where the main processes are dissociation of VO and V₂O, migration and subsequent trapping of VO ultimately giving rise to the electrically inactive vacancy-dioxygen pair (VO₂) and interactions involving atomic hydrogen.