Impurity-Vacancy Defects in Implanted Float-Zone and Czochralski-Si

The dual implantation method developed for defect engineering [O.W. Holland et al, J. Electron. Mater, 25, 99 (1996)] uses an amorphizing implant in conjunction with high energy Si sup + -ion implantation to inject vacancies. Following annealing of the implanted samples for 20 minutes 16 600C and at 800C, the amorphous layer re-crystallizes by solid-phase epitaxial growth (SPEG), and the unwanted interstitials are consumed by recombination with vacancies. Doppler broadening of annihilation radiation and beam positron lifetime measurements reveal that there are residual divacancy-impurity complexes formed in the SPEG layer. Since the effect is nearly identical in both float-zone and Czochralski-Si, the source of the impurities is not likely to be residual oxygen in the unimplanted crystals.