Dependence of nitrogen incorporation on beam energy during ion nitriding of Al

Ion nitriding of Al has been performed by a nitrogen reactive ion beam using a hot filament ion source. The N incorporation has been determined at different beam voltage from 0.4 kV to 2.4 kV with an ion current density of 0.2 mA/cm2, and a substrate temperature of 350°C. For this purpose, the beam has been characterised in terms of ion flux, ion composition and energy distribution using an energy selective mass spectrometer and a Faraday cup. From the beam parameters, N loss due to sputtering and backscattering has been calculated as a function of the ion energy using dynamic binary collision computer simulations. The total amount of incorporated N measured by Nuclear Reaction Analysis (NRA) is consistent with the incident N fluence and the N loss obtained from the simulation. A discrepancy is observed for a beam voltage lower than 0.8 kV due to the stationary surface oxide layer reducing the rate of nitrogen incorporation during ion nitriding of Al.