Effect of Germanium Doping on the Production and Evolution of Divacancy Complexes in Neutron Irradiated Czochralski Silicon

Fourier transformed infrared absorption spectroscopy was used to investigate the effect of germanium (Ge) doping on the production and evolution of divacancy (V-2) complexes in neutron irradiated Czochralski (Cz) silicon. The generation rates of V-2 and vacancy-oxygen (VO) complexes were found to increase in Ge doped silicon as compared with the controlled Cz silicon, which could be ascribed to the increased availability of vacancies in Ge doped silicon arising from the temporary trapping of vacancies associated with the transient GeV pairs. Upon annealing, most of the V-2 complexes were eliminated via the reaction between divacancy and self-interstitials (Si-i) (V-2 + Si-i -> V), while only 6-24% of V-2 complexes were transformed into V2O complexes via the trapping of V-2 complexes by interstitial oxygen (Oi), as V-2 diffuses much faster than O-i. It was observed that Ge doping accelerated the V-2 annihilation and in turn suppressed the transformation of V-2 into V2O complexes. Those phenomena can be attributed to the increased availability of free self-interstitials in Ge doped silicon, which enhances the recombination of V-2 with Si-i. Additionally, an increased production of V3O complexes was observed in Ge doped silicon. The role of Ge atoms in the V3O formation was discussed in view of the two reactions V-2 + VO -> V3O and V2O + V -> V3O.