Transformation of radiation defect clusters in B+ ion-implanted silicon

DLTS is used to study the defect accumulation in n-type silicon implanted with 135 keV B+ ions in the dose range from 10(11) to 3 x 10(13) cm(-2) at room temperature. The obtained results are compared with those for neutron-irradiated silicon where amorphization is known not to occur. It is found that deep levels, typical for neutron-irradiated silicon, are observed in ion-implanted crystals only after low doses (<10(12) cm(-2)). Starting from some ion doses essential changes are seen in DLTS spectra. These changes, in our opinion, are caused by defect cluster transformations (growth) which precede amorphization. The dose required for the changes in the DLTS spectra increases if the crystal contains impurities (for example oxygen) actively interacting with the point defects. It is equal to 3 x 10(11) and 3 x 10(12) cm(-2) for Si-FZ and Si-CZ, respectively, doped with phosphorus to 4 x 10(15) cm(-3).