Transmission electron microscopy study of damage by ion implantation in gold Evidence for a spike threshold

Abstract

Nine different atomic species, from K to Yb, have been implanted into gold at energies ranging from 20 to 150 keV. The nature and depth distribution of the resultant defect clusters were studied by transmission electron microscopy techniques as well as by a modification of the 21/2-dimensions stereo technique developed by Mitchell and Bell (1976). The effects of implanted ion dose and sample purity were determined. The cluster depth distributions are in overall agreement with the damage distributions deduced from the energy-deposition calculations of Winterbon, Sigmund and Sanders (1970). The nature of the defect clusters is found to depend on the mass and energy of the incoming ion, in agreement with our previously reported work. It is suggested that these provide evidence for the decisive influence of the deposited energy density on the nature of visible damage. We conclude that it is possible to distinguish between cascade and ‘spike’ effects, the latter setting in when the average energy per atom in the cascade is approximately 2 eV/atom. All results known to us (obtained at low doses on pure samples for a variety of ion species in Au, Au, Cu, W, Mo and Ni) may be related to each other in this way.