The Wet Corrosion of Molybdenum Thin Film - Part IV: The Effect of Nitriding

A considerable number of detailed investigations have been carried out on the deposition and characterisation of molybdenum and molybdenum-titanium-nitride films by employing a variety of techniques. However, very little is currently known about the effect of composition (N-2/Ar flow rate) on the corrosion properties of MoN and MoTiN thin films for aggressive ambient conditions. In this work, the electrochemical and corrosion behaviour of MoN and MoTiN thin films, produced by Physical Vapour Deposition (PVD) with different N2/Ar flow rates, has been investigated by Electrochemical Impedance Spectroscopy (EIS) in aerated alkaline chloride solution and compared with the behaviour of pure molybdenum in the same environment. Results obtained indicate that increasing nitrogen content in the film leads to a beneficial effect on the corrosion resistance, but results in decreased electrical conductivity of the film that may limit their application as back contact in photovoltaic modules.