The use of an Al sacrificial layer to improve retention during high dose Pt ion implantation into Ni

Abstract

Our previous work [Clapham, Whitton, Ridgway, Hauser, and Petrovic, J. Appl. Phys. 72, 4014 (1992) and Clapham, Whitton, and Ruck, Nucl. Instrum. Methods B 80/81, 501 (1993)] has shown that the sputtering limitation often associated with high-dose, heavy ion implantation into metals can be overcome by using a thin (∼1000 Å) C sacrificial layer. This layer, which is deposited on the surface prior to implantation, sputters slowly during bombardment, thus protecting the underlying target. The present study further investigates the potential of the sacrificial layer technique, using Al as a sacrificial layer on a Ni target implanted with high doses (to 7×1017 ions/cm2) of 5 MeV Pt ions. The Al layer was found to be very effective in enhancing retention of the implanted Pt, with 100% retention and a maximum concentration of 19 at. % Pt achieved for the highest dose. This compares with a saturation concentration of ∼10 at. % Pt when no sacrificial layer was used. The mixing behavior of Al into Ni was consistent with other studies conducted at lower ion energies. The temperature region of radiation-enhanced diffusion was established, and the phase Ni3Al was found to be present in the Al/Ni mixed region after Pt bombardment.