Electrochemical deposition of Zn on TiN microelectrode arrays for microanodes

• Published in: Electrochemistry communications Vol. 9; no. 2; pp. 303 - 309
• Main Authors: Ferapontova, E.E., Terry, J.G., Walton, A.J., Mountford, C.P., Crain, J., Buck, A.H., Dickinson, P., Campbell, C.J., Beattie, J.S., Ghazal, P., Mount, A.R.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01-02-2007; Amsterdam Elsevier Science; New York, NY
• Subjects: Applied sciences; Chemistry; Electrochemical deposition; Electrochemistry; Electrodeposition; Electronics; Exact sciences and technology; General and physical chemistry; Microanodes; Microelectrode arrays; Microelectronic fabrication (materials and surfaces technology); Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Study of interfaces; Titanium nitride; Zinc; Electrochemical deposition; Titanium nitride; Microanodes; Microelectrode arrays; Zinc; Scanning electron microscopy; Anode; Transition metal; Electrode material; Surface treatment; Surface structure; Array; Morphology; Microelectrode; Electrodeposition; Zinc sulfate; Electrochemical reaction
• ISSN: 1388-2481; 1873-1902
• DOI: 10.1016/j.elecom.2006.09.005

Zn was electrochemically deposited onto square TiN electrodes with edge dimensions of 490
μm and 40
μm. These were fabricated by standard microfabrication techniques, which provide an extremely reproducible electrode for experimentation. Reliable constant-potential electrodeposition of Zn on the TiN was performed at −1.2
V, just below the Zn/Zn
2+ redox potential. At more negative potentials, the hydrogen evolution reaction on TiN interfered with bulk metal electrodeposition, resulting in poor quality Zn films. A two-step plating procedure was shown to be most efficient for electrochemical deposition of Zn, with Zn nucleation on the TiN substrate at high cathodic overpotential during the first step and a second step of bulk metal growth on the nucleated layer at low cathodic overpotential. These results were most consistent with 3D progressive nucleation of Zn on the TiN surface. Using this procedure, deposits of Zn on 490
μm TiN electrodes were uniform. In contrast, Zn deposits on 40
μm electrodes formed high-surface area and volume surface structures resulting from preferential growth at the electrode corners due to enhanced hemispherical diffusion at these sites. This should enable the formation of high surface area, high current density Zn anodes on biocompatible TiN microelectrodes, which could find application as improved microanodes for implantable miniature power supplies, e.g., implantable glucose sensors and internal cardioverter defibrillators.