Electrochemical characteristics of NixN thin films deposited by DC and HiPIMS reactive magnetron sputtering

Abstract This study deals with the DC and HiPIMS reactive magnetron deposition process using a pure nickel target (99.995%) in an Ar-N 2 gas mixture with varied nitrogen gas flow and bias voltage (floating or -100 V). The characterization of the NiN films has been carried out by X-ray diffraction (XRD), X-ray photoelectrons spectroscopy (XPS) and Energy dispersive X-ray Spectroscopy (EDXS). XRD measurements have highlighted the deformation of the Ni cubic cell as a function of nitrogen content, and a mixture of nitrided phases (Ni 4 N, Ni 3 N and Ni 2 N) appears for 20% N 2 in the discharge. XPS and EDX are well correlated and permit us to determine three zones: metallic between 0 and 20% N 2 , Ni 4 N between 20% and 42% N 2 and finally Ni 3 N for N 2 above 50%. These three zones are in good agreement with deposition rates and optical emission spectroscopy measurements. Cyclic voltammetry has been performed in a conventional three-electrode cell using neutral, alkaline and acidic aqueous electrolytes. The Ni x N electrochemical behavior shows a pseudocapacitive charge storage mechanism in LiNO 3 and KOH electrolytes using an appropriate voltage window, suitable for supercapacitors, whereas Ni x N exhibits reversible faradaic redox peaks beyond one potential in KOH, depicting Ni x N film as a battery-type electrode.