Depth Dependence and Chemical Effects in Ion Mixing of Ni on SiO2

Abstract

ABSTRACTWe report on our studies of Ni transport induced by 290 keV Xe irradiation of thin Ni films evaporated on thermally grown SiO2 at Xe fluences of 1015–1016 cm−2 and at temperatures of 77–750 K during irradiation. A simple etching technique was used to remove the free Ni leaving the SiO2 layer with incorporated Xe and Ni, whose profiles are directly measured using 2 MeV He+ backscattering spectrometry.Marker experiments are used to verify the selectivity of the etching procedure. An apparent discontinuity in the Ni concentration across the Ni-SiO2 interface may produce the high selectivity observed within our etching process. Features associated with both cascade mixing and recoil implantation are readily discernible in the residual metal profiles. An exponential tail is evident beyond ∼ 500 Å of the SiO2 and is insensitive to temperature. within 500 Å of the surface the Ni profile demonstrates a strong temperature dependence which affects both the cascade mixing and recoil implantation processes. These profiles show favorable agreement with theory for samples implanted at temperatures of ≤ 300 K, while deviations in the high temperature behavior suggest a way chemical effects may alter the collision processes.