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O: Oberflächenphysik

O 13: Solid-liquid interfaces

O 13.8: Vortrag

Montag, 27. März 2006, 16:45–17:00, WIL C207

Exploring the diamond/aqueous electrolyte interface — •Jose Antonio Garrido, Stefan Nowy, Andreas Härtl, Jorge Hernando, and Martin Stutzmann — Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching

The diamond surface is a unique platform for the investigation of the charged solid/liquid interfaces. Both carbon-hydrogen (C-H) and carbon-oxygen (C-O) surface groups are stable in aqueous solutions, and show a completely different behavior in terms of wetting by water and the resulting charge state. Furthermore, under certain conditions a highly conductive p-type channel is induced at the surface of H-terminated undoped diamond films, which can be used for charge sensing applications. In this contribution, we report on the electrochemical characterization of modified C-H and C-O diamond surfaces in contact with aqueous electrolytes. For this purpose, we have investigated surface conductive single crystalline films as well as boron-doped metal-like polycrystalline and nitrogen-containing ultrananocrystalline diamond films. Using impedance spectroscopy we study the influence of different surface terminations on the interfacial capacitance. Surface charging processes have been investigated as a function of electrolyte pH. The effect of screening and/or specific adsorption of electrolyte ions will be discussed. This work has direct implications for an understanding of the pH and ion sensitivity of diamond surfaces, as well as the physisorption of charged biomolecules on these surfaces.