Residual lattice disorder in self-implanted silicon after pulsed laser irradiation

Double crystal X-ray diffractometry is employed to investigate residual lattice disorder in self-ion implanted silicon after pulsed laser irradiation. The defects responsible for the observed disorder are found to decrease the lattice parameter of silicon and to extend to depths much greater than the thickness of the initial amorphized crystal. It is possible to distinguish a thin relatively undamaged surfacial layer from an underlying more disordered region. Isochronal treatments show that the crystal perfection is completely recovered at temperatures of the order of 1000 °C, whereas isothermal treatments and transmission electron microscopy observations, made on fully annealed samples, allow to evidence the presence of carbon and oxygen in the damaged crystal. The trend of the isochronal curves and the sign of the lattice strain suggest that substitutional carbon, carbon- and oxygen- related centres and multivacancy complexes are responsible for the observed residual lattice disorder.