Low energy ion beam modification of Cu/Ni/Si(100) surface

Abstract

Cu/Ni bilayer has been prepared by thermal evaporation of pure Cu and Ni metals onto Si(100) surface in high vacuum; it was sputtered using argon ion beam in ultra-high vacuum. The ion beam-induced surface and interface modification was investigated using X-ray photoelectron spectroscopy and atomic force microscopy techniques. The deposited sample exhibits the formation of CuO nano-structures of size 40 nm on Cu surface and after sputtering with argon ion beam at a fluence of 5 × 10 ¹⁵ ions/cm², the surface exhibits a mound structure with an average size of about 100 nm. Interestingly, with sputtering at higher fluence of 2⋅4 × 1 0 ¹⁶ ions/cm², the surface exhibits broad pits of sizes ranging from 100 to 300 nm with an average depth of 10 nm. Bottom surface of these pits contains Ni atoms. The Cu 2p _3/2 peak exhibits a shift of 0⋅3 eV towards high binding energy and also a large asymmetry of 0⋅11 after sputtering at high fluence compared with pure copper. These changes are attributed to Cu–Ni interactions at the interface.