Type of presentation: Poster

IT-13-P-2704 Focused ion beam patterning of boron-doped diamond electrodes: Influence of patterning parameters on the heterogeneous electron transfer behavior

Eifert A.1, Langenwalter P.1, Higl J.2, Lindén M.2, Nebel C.3, Mizaikoff B.1, Kranz C.1
1Institute of Analytical and Bioanalytical Chemistry, University of Ulm, Ulm, Germany, 2Institute of Inorganic Chemistry II, University of Ulm, Ulm, Germany, 3Fraunhofer Institute for Applied Solid State Physics, Freiburg, Germany
alexander.eifert@uni-ulm.de

Diamond with its large band gap of 5.49 eV can be transformed into a metallic-like semiconductor by doping with very high boron concentrations. This new electrode material outmatches many common electrode materials concerning potential window, chemical inertness and signal-to-noise-ratio. The superior chemical and physical properties in combination with the possibility to fabricate microelectrodes or microelectrode arrays for example with FIB [1, 2], renders them highly suitable for bioanalytical applications. The electrochemical behavior of BDD electrodes depend on a variety of parameters, such as doping level, defects, carbon impurities, crystal orientation, surface termination/modification and grain boundaries [3]. Patterning of BDD with FIB technology leads to damages due to the ion bombardment such as amorphization and hence changes the overall electrochemical behavior.
In this contribution we present the influence of different FIB patterning parameters on the electrochemical properties such as heterogeneous electron transfer rate constant and peak separation of the obtained BDD microelectrode arrays. Post fabrication electrochemical treatments will restore to a certain extent the electrochemical properties. Next to electrochemistry also Raman spectroscopy was applied to characterize the ion irradiated sample, which will also be presented.

References
[1] J. Hees, R. Hoffmann, A. Kriele, W. Smirnov, H. Obloh, K. Glorer, B. Raynor, R. Driad, N. Yang, O. A. Williams, C. E. Nebel, ACS nano 5 (2011) 3339–3346.
[2] A. Eifert, W. Smirnov, S. Frittmann, C. E. Nebel, B. Mizaikoff, C. Kranz, Electrochem. Commun. 25 (2012) 30–34.
[3] K. B. Holt, A. J. Bard, Y. Show, G. M. Swain, J. Phys. Chem. B 108 (2004) 15117–15127.

The Focused Ion Beam Center UUlm, which is supported by FEI Company (Eindhoven, Netherlands), the German Science Foundation (INST40/385-F1UG), and the Struktur- und Innovationsfonds Baden-Württemberg are greatly acknowledged. This work was supported by the project "Methoden für die Lebenswissenschaften P- LSMeth/23" funded by the Baden-Württemberg Stiftung.

Fig. 1: Rate constants calculated from recorded CVs after electrochemical treatment. Electrochemical measurements were recorded in a solution containing 10 mmol/l K4[Fe(CN)6], 0.016 mol/l Tween 20 and 0.1 mol/l KCl. The influence of dwell time dependency was investigated at an accelerating voltage of 30 kV and a beam current of 15 nA.

Fig. 2: Raman spectra recorded after different fabrication steps of the microelectrode arrays. Raman spectra were acquired using an excitation laser with 532 nm and 10 mW power. For detection a 100x objective with a 0.9 numerical aperture was used.