Damage profiles in as-implanted <100> Si crystals: strain by x-ray diffractometry versus interstitials by RBS-channeling

The strain versus interstitials correlation for as-implanted [100] silicon crystal was studied comparing the strain profiles with the displaced atom profiles and the strain integral with the total fraction of displaced atoms as measured by X-ray diffractometry and Rutherford backscattering-channeling spectrometry, respectively. Light/medium (B, N and O) and heavy (Si and As) mass ions at low (50 keV) and high (0.7 or 0.8 MeV) energy, low dose rate (less than or equal to 3 x 10(12) ion/cm(2)/s) and fluences between 2 x 10(12) and 3 x 10(15) ion/cm(2) were implanted at room temperature and random incidence in [100] Si wafers. Independently of the ion energy two correlations between strain and displaced atoms can be given depending on the ion mass and the damage level. For light mass ions at low damage level (less than or equal to similar to 6%) a linear relation exists between strain and interstitials. For heavy mass ions at any damage level and for low mass ions at damage level > similar to 6%, the correlation between strain and displaced atoms is sublinear. Isochronal annealing treatments show that the predominant defects produced by high mass ions are different from those produced by low mass ions. Once interpreted in the frame of the elastic theory of solid, the linear relation between strain and interstitials may allow an evaluation of the relative volume increase per interstitial in silicon.