A study of low energy high dose nitrogen ion implantation in iron – Effect of ion energy and current density

Abstract Iron foil samples of 0.125 mm thickness, with a purity of 99.95%, were implanted with molecular nitrogen ions (N 2 + ) at energies of 2, 3, 4 and 5 keV at current densities of 1 and 5 μA/cm 2 for each ion energy. The ion doses for these experiments ranged from 6 × 10 16 to 3 × 10 17 ions/cm 2 . The concentration profiles of nitrogen ions implanted into iron were measured by means of X-ray Photoelectron Spectroscopy (XPS) and these were compared with profiles created using the computer simulation model SATVAL (J. Sielanko, W. Szyszko, Surf. Sci. 161 (1985) 101; J. Sielanko, W. Szyszko, Nucl. Instr. and Meth. B 16 (1986) 10). The chemical composition and chemical structure of the implanted iron was investigated by XPS and Angle Resolved X-ray Photoelectron Spectroscopy (ARXPS). The maximum achievable nitrogen concentration was about 10%. It is concluded that this is chemically combined with Fe, probably to form the nitride F 16 N 2 phase. Simulations suggest that N concentrations should be greater than the 10% measured. The differences may be accounted for by considering surface segregation.