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 510 12 cm 3 and oxygen content of 2‐310 17 cm 3 have been irradiated with 15 MeV 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 205 °C‐285 °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 1.3 eV. 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, DV2 0 , for V 2 is in the range 3±1.510 3 cm 2 /s, which agrees well with a simple theoretical model of V2 diffusion in Si.