Laser annealing of Pb-implanted silicon

The effect of irradiation with a Q-switched ruby laser pulse of 50 ns duration on Pb-implanted Si〈111〉 substrates is investigated by MeV He Rutherford backscattering in glancing geometry. The amount of implanted Pb atoms accumulated at the crystal surface after laser irradiation increases with laser power density in the range 15 to 100 MW/cm2. Reordering of the implanted layer takes place simultaneously with Pb accumulation on surface for all the investigated fluences. This behavious differs from thermal aging where the Pb profile is independent of temperature in the range 600 to 800°C and the substrate reordering is inhibited mainly at fluences higher than 1015 cm−2. The differences between thermal and laser annealing could be ascribed to a quasi liquid transition of the as-implanted amorphous layer during laser irradiation. An interpretation along this line is presented.