B implanted at room temperature in crystalline Si: B defect formation and dissolution

The B lattice location of B implanted into crystalline Si at room temperature has been investigated using the nuclear reaction 11B(p,α)8Be induced by 650 keV proton beam and channelling analyses. The angular scans along the 〈1 0 0〉 and 〈1 1 0〉 axes indicate the formation of a particular B complex with B atoms non-randomly located. The same defect has been observed also for B doped Si where the B atoms, initially substitutional and electrically active, have been displaced as consequence of the interaction with the point defects generated by proton irradiation. The angular scans were compatible with the B–B pairs aligned along the 〈1 0 0〉 axis predicted by theoretical calculations. ermal evolution in the 400–950 °C range of the B complexes has been inferred both by B lattice location measurements and electrical activation. At low temperature (<700 °C) only 10% of the total B dose is active and a significant increase of randomly located B occurs. A significant electrical activation consistent with the concentration of substitutional B occurs at temperature higher than 800 °C. The data are interpreted in terms of a formation and dissolution of the B complexes.