On the annealing behaviour of dysprosium ion implanted nickel: A combined study using Rutherford backscattering, transmission electron microscopy, and total current spectroscopy

Abstract

Despite continuing improvements in applications of the analytical method of Rutherford backscattering (RBS) to solid state physics it is recognized that more complete information can be obtained if other techniques - for example transmission electron microscopy (TEM) - are employed simultaneously. Experiments are described in which a combined RBS and TEM study of the annealing of nickel, rendered amorphous by implantation of 20 keV dysprosium ions is supplemented with a completely new technique - total current spectroscopy (TCS). In TCS low energy electrons (0–15 eV) are used to probe the damaged nickel. Observations have been made during annealing of both the reappearance of the bulk band structure of the metal and of a “surface peak” which is highly sensitive to the recovery process. Changes in the height of the surface peak reveal three sharp annealing stages, the first two being preceded by reverse annealing which correlates well with RBS and TEM results. The first annealing stage - following the amorphous to crystalline transition - may be associated with electronic effects in the vicinity of the Curie point. Changes in the position of the surface peak allow one to trace the diffusion of dysprosium to the surface. Quantum-mechanical resonances at the damage/crystal interface have also been followed throughout annealing. The initially amorphous layer (∼ 2.2 nm) increases in thickness slightly during recovery. A much fuller picture of the complicated solid state annealing processes taking place is obtained if the three techniques are used together. In the case of dysprosium implanted nickel TCS appears to give a more accurate measure both of the annealing stages and the layer thickness than does RBS.