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 (V2) complexes in neutron irradiated Czochralski (Cz) silicon. The generation rates of V2 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 V2 complexes were eliminated via the reaction between divacancy and self-interstitials (Sii) (V2 + Sii → V), while only 6–24% of V2 complexes were transformed into V2O complexes via the trapping of V2 complexes by interstitial oxygen (Oi), as V2 diffuses much faster than Oi. It was observed that Ge doping accelerated the V2 annihilation and in turn suppressed the transformation of V2 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 V2 with Sii. 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 V2 + VO → V3O and V2O + V → V3O.