Effect of germanium doping on the annealing characteristics of oxygen and carbon-related defects in Czochralski silicon

This paper is devoted to the annealing studies of defects produced in carbon-rich Ge-doped Czochralski-grown Si (Cz-Si) by 2 MeV electron irradiation. The annealing temperature of vacancy-oxygen (VO) complexes, carbon interstitial-oxygen interstitial ( C i O i ) , and carbon interstitial-carbon substitutional ( C i C s ) pairs as well as the formation temperature of vacancy-two oxygen ( VO 2 ) complexes are monitored as a function of Ge concentration. It has been established that the annealing of C i O i and C i C s defects remains practically unaffected by the Ge presence, whereas the annealing temperature of VO defects and the formation temperature of VO 2 complexes are substantially lowered at Ge concentrations larger than 1 × 10 19 cm − 3 . The hydrostatic component of elastic strains introduced by Ge atoms in the Si crystal lattice was calculated. It appears to be very small, at least insufficient to exert a pronounced effect upon the annealing behavior of radiation-produced defects. This conclusion is in line with what is observed for the C i O i and C i C s species. In the case of VO, whose annealing process in Cz-Si is concurrently conducted by two reaction paths VO + O i → VO 2 and VO + Si I → O i , we suggest that the latter reaction in Ge-doped Cz-Si is enhanced by emitting self-interstitials ( Si I ) from loosely bound self-interstitial clusters predominantly formed around Ge impurity atoms. As a result, the liberation of self-interstitials at lower annealing temperatures leads to an enhanced annealing of VO defects. An enhanced formation of VO 2 complexes at lower temperatures is also discussed in terms of other reactions running in parallel with the reaction VO + Si I → O i .