Metastable-defect behaviors of iron-boron pairs in silicon

Structurally metastable Fe_i-B_s pairs in silicon have been detected using dark or photo capacitance-transient technique combined with minority-carrier injection below 200 K. Five levels at E_C-0.43 eV, 0.46 eV, 0.52 eV, and 0.54 eV and E_V+0.53 eV are observed as the metastable defects after the injection. These defects annihilate by annealing at 250 K for a few minutes. The transmutations for respective defects are confirmed by isochronal anneals, and the reaction kinetics are studied by isothermal anneals. From these investigations, the pair configurations responsible for these new defect levels are proposed.