We report extensive cyclic voltammetric evaluation of gold submicrometer edge band electrodes with different widths, from 25.3 to 143.5 nm. Fabrication of these band electrodes from layers of gold and silicon nitride using conventional microfabrication techniques, was reported in the preceding companion paper. Gold film thicknesses and, thus, the electrode widths were measured by surface profilometry, X-ray interferometry, and atomic force microscopy. The electrodes exhibit typical sigmoidal-shaped cyclic voltammograms at slow scan rates (<1 V/s). The limiting currents deviate from theoretical values as electrode width decreases. At larger widths, experimental values are in better agreement with theory, consistent with trends reported in the literature. Maximum current is much higher than expected for all widths at fast scan rates (> 25 V/s). Capacitance of the edge band electrodes is high (187−0.206 mF/cm2 for 71.2-nm edge band electrodes for scan rates of 0.010−204 V/s) and scan rate dependent. Values approach those of macroelectrodes at fast scan rates, indicating imperfect seals at the gold/silicon nitride, gold/Cr/glass, or gold/epoxy interfaces.

Useful analytical application of submicrometer band electrodes depends strongly upon developing reproducible, convenient fabrication and characterization procedures. We report fabrication of arrays of individually addressable submicrometer band electrodes that are 2 mm long and functional down to 37.0 nm in width, using multilayered materials and conventional microfabrication techniques. Fabrication involves thermal vapor deposition of a chromium adhesion layer and a gold layer on glass, followed by plasma-enhanced chemical vapor deposition of a silicon nitride layer, photolithography, and reactive ion etching. The topography of each layer was studied using contact-mode atomic force microscopy. Surfaces show larger features as the thickness of gold increases. Silicon nitride topography shows a relatively smoother surface, indicating that it may serve as a planarizing layer for subsequent gold layers. Cyclic voltammetry at 0.10 V/s of individual band electrodes in a solution of Ru(NH3)6 3+ shows a typical sigmoidal response, as would be expected when the diffusion layer exceeds the smallest dimension of the electrodes. At faster scan rates, peak-shaped voltammograms are observed, as expected. Good reproducibility of electrochemical behavior was obtained for electrodes in the same array.

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