On the effectiveness of dislocation loops as sites for the adsorption of implanted ions

It is commonly found that when conventional dopant ions are implanted into a semiconductor, only a fraction of the total number implanted will exhibit the electrical behavior that would be expected for an atom of that type in a regular substitutional position. In this paper we present semi-quantitative calculations which suggest that many of the implanted ions can be adsorbed on dislocation loops that are produced when the implanted layer is annealed. The effect is particularly large when there is a significant size mismatch between the implanted ion and the host atom. The theory gives a reasonable fit to experimental results if it is assumed that the adsorbed ions are either electrically inactive or else characterized by relatively large carrier ionization energies.