A study was made of the correlation between strain and interstitial content in as-implanted (100) crystals. This was done by comparing strain profiles with displaced atom profiles, and the strain integral with the total fraction of displaced atoms, as measured by using X-ray diffractometry and Rutherford back-scattering channelling spectrometry. Implantation was performed using light (B, N, O) or heavy (Si, As) ions of low (50keV) or high (0.7 or 0.8MeV) energy at a dose rate of less than 3 x 1012/cm2s to a fluence of between 2 x 1012 and 3 x 1011/cm2. These ions were implanted into (100) wafers, at room temperature, using a random angle of incidence. Regardless of the ion energy, 2 correlations between strain and number of displaced atoms were found; depending upon the ion mass and damage level. In the case of light ions at low damage levels (less than 6%) a linear relationship existed between strain and interstitial concentration. In the case of heavy ions at any damage level, and for light ions at damage levels above 6%, the correlation between strain and number of displaced atoms was sub-linear. Isochronal annealing treatments showed that the predominant defects which were produced by heavy ions were different to those produced by light ions. It was suggested that an explanation of the linear relationship between strain and interstitial content, in terms of the elastic theory of solids, would permit the evaluation of the relative volume increase per interstitial.

R.Nipoti, M.Servidori, M.Bianconi, S.Milita: Nuclear Instruments and Methods in Physics Research B, 1996, 120[1-4], 64-7