X-ray rocking curve analyses were used to investigate damage accumulation, with increasing dose, in material that was implanted with 50keV or 1MeV 11B+ ions, and 50keV, 180keV or 0.7MeV 28Si+ ions. The build-up of damage was monitored by determining the maximum value of the lattice strain normal to the surface, and its depth integral. The lattice-strain profiles were obtained within a dynamic diffraction formalism, by using automated best fits to experimental X-ray rocking curves. It was shown that, for doses below the amorphization limit, the damage increased sub-linearly with dose and in very different manners for B and Si ions. The sub-linearity resulted from the inter-cascade recombination of point defects that were produced by bombardment. Small differences in the sub-linearities for the 2 ions could be attributed to the different forms of aggregation into which the surviving defects evolved when the dose approached the amorphization threshold. However, the study of damage growth had to cease at the upper dose where a continuous buried amorphous layer began to form. Starting from this dose, a simple semi-kinematic diffraction model showed that the determination of a unique peak value of the lattice strain normal to the surface depth profile, and hence of its integral, was not possible. This was a result of the fact that the sample behaved like an X-ray interferometer when an embedded amorphous layer was present.

S.Milita, M.Servidori: Journal of Applied Physics, 1996, 79[11], 8278-84