The elastic properties of ion-implanted silicon

The elastic properties of silicon implanted with As+ and Si+ in the dose range 1014 to 1015 ion cm-2 has been investigated. Reflection scanning acoustic microscopy techniques have been used to determine changes in the velocity of surface elastic waves (Rayleigh waves) on ion-implanted silicon. With the aid of theoretical models for this mode of wave propagation, the experimental velocity changes have been interpreted in terms of changes in the elastic constants of the implanted layer. These changes have been found to be dependent upon the level of radiation damage produced by the implantation process. Decreases of approx. 30% in the bulk and shear elastic constants have been deduced for damage levels present at the onset of implantation-induced amorphization. (author)