X-RAY-DIFFRACTION ANALYSIS OF DAMAGE ACCUMULATION DUE TO THE NUCLEAR-ENERGY LOSS OF 50 KEV AND 1-2.2 MEV B IONS IMPLANTED IN SILICON

Computer simulation of double-crystal X-ray rocking curves was employe d to investigate the damage accumulation produced in silicon by implan ting increasing doses of boron ions at 50 keV and 1-2.2 MeV energies. Under implant conditions preventing target heating, low-energy-induced damage was found to increase sublinearly with dose. In particular, tw o trends were observed, characterized by different deviations from lin earity. The more marked one is in the range of relatively high doses. This suggests that, besides strain recovery expected by recombination of Frenkel defects of opposite type inside each ion track, which would be consistent with a linear damage growth, a defect recombination mec hanism must occur among different tracks, playing a progressively impo rtant role at increasing doses. Preliminary results obtained at B ener gies in the range 1-2.2 MeV seem to indicate that the same mechanisms operate at high implant energy.