Role of nitrogen doping at the surface of titanium nitride thin films towards capacitive charge storage enhancement

• Published in: Journal of power sources 2017-08, Vol.359, p.349-354
• Main Authors: Achour, A., Chaker, M., Achour, H., Arman, A., Islam, M., Mardani, M., Boujtita, M., Le Brizoual, L., Djouadi, M.A., Brousse, T.
• Format: Article
• Language: English
• Subjects: Computer Science; Electrochemical capacitors; Electronics; Engineering Sciences; Networking and Internet Architecture; Nitrogen doping; Oxidized surface; Thermal annealing; Titanium nitride
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2017.05.074

We recently reported an impressive cycling stability (over 20,000 cycles) of titanium nitride (TiN) electrodes with high specific capacitance. It is anticipated that nitrogen (β−N) doping in the oxidized surface of TiN film plays a crucial role in charge storage mechanism and stability of this material. In this work, we offer an evidence on the effect of β−N doping on improvement in specific capacitance of vacuum annealed TiN thin films. The annealing of the TiN films leads to the diffusion of the excess β−N from sub-surface to oxidized TiN film surface without further oxidation of the electrode surface. We demonstrate an increase in the TiN areal capacitance upon an increase in the amount of β−N dopant. The areal capacitance of the annealed films was enhanced by 3-fold (8.2 mF cm−2 in K2SO4 aqueous electrolyte) without sacrificing the cycling stability of the electrodes after more than 10,000 consecutive charge/discharge cycles. [Display omitted] •Reactive sputtering of TiN films was carried out with annealing at ≤550 °C.•Excess β−N in the annealed TiN surface causes 3-fold increase in areal capacitance.•The maximum areal capacitance was 8.2 mF cm−2 with no loss after 10,000 cycles.•β−N doping of oxidized TiN film improves charge storage of these electrodes in ECs.