Kinetics of divacancy annealing and divacancy-oxygen formation in oxygen-enriched high-purity silicon

In this work the thermal kinetics of the transformation from the divacancy (V₂) to the divacancy-oxygen (V₂O) complex has been studied in detail, and activation energies, (Eₐ), have been obtained. Diffusion oxygenated float-zone silicon (DOFZ-Si) samples of n-type with a doping of 5×10¹²0.3em0excm^-3 and oxygen content of (2--3)×10¹⁷0.3em0excm^-3 have been irradiated with 150.3em0exMeV electrons. Isothermal annealing studies of electrically active defects have been performed by means of deep-level transient spectroscopy. Heat treatments at temperatures in the range 2050.2em0ex^∘C--2850.2em0ex^∘C have all shown a shift in the singly negative and doubly negative divacancy levels, due to the annealing of V₂ and the formation of V₂O. By studying the temperature-dependent rate of this process which exhibits first order kinetics, it has been found that both the annealing V₂ and the formation of V₂O have activation energies of ≈1.30.3em0exeV. This value is ascribed to migration of V₂, and the results favor strongly a model where V₂ is trapped by interstitial oxygen atoms during migration. In addition, the process takes place with a high efficiency since the loss of V₂ and the growth of V₂O display a close one-to-one proportionality. Finally, it has been found that the diffusivity pre-exponential factor, D_V₂⁰, for V₂ is in the range 3±1.5×10^-30.3em0excm²∕s, which agrees well with a simple theoretical model of V₂ diffusion in Si.