Lattice location and thermal evolution of small B complexes in crystalline Si

The lattice location of B in Si has been investigated by channelling analyses using nuclear reactions (⁠$650keV$ proton beam, $B11(p,α)Be8$⁠). The formation at room temperature of a specific, small B complex in presence of an excess of point defects has been inferred. In particular, B implanted in Si or B substitutional dissolved in Si and irradiated with proton beam form a unique B complex with B atoms not randomly located. The angular scans along the ⟨100⟩ and ⟨110⟩ axes are compatible with B–B pairs aligned along the ⟨100⟩ axis. The thermal annealing in the $200–950°C$ range of the B complexes, analyzed by lattice location and carrier concentration measurements, depends on the residual defect density in the lattice. The B complexes dissolve at low temperature if no excess of Si self-interstitials (Is) exists or they evolve into large B clusters and then dissolve at high temperature if Is supersaturation holds.