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O: Fachverband Oberflächenphysik

O 76: Focussed Session: Solid-liquid Interfaces II

O 76.8: Vortrag

Donnerstag, 14. März 2013, 18:30–18:45, H31

Structural Control of ZnO Thin Films Electrochemically Grown on Microstructured Electrodes — •Martina Stumpp, Christian Lupo, and Derck Schlettwein — Justus-Liebig-Universität Gießen, Institut für Angewandte Physik, Heinrich-Buff-Ring 16, D-35392 Gießen

Zinc oxide (ZnO) can be used as electrode material in dye sensitized solar cells and in microelectronic devices. Electrochemical deposition is an energy-efficient and economic processing method to obtain compact or porous crystalline thin films of ZnO. Microelectrodes were used as substrates for the electrodeposition of ZnO under pulsed galvanostatic conditions from aqueous zinc nitrate solutions. The ZnO growth was characterized by scanning electron microscopy and confocal laser microscopy. For current densities below the limiting current density, homogenous films were obtained, whereas for current densities greater than those limited by the diffusion of Zn²⁺ and NO₃⁻, strongly dendritic structures were formed. The geometric distribution of the transport of the precursors from solution relative to the electrode surface and the subsequent formation of ZnO was discussed based on a model of a duplex diffusion layer. When polarizing only one of two sets of interdigitated microstuctured electrode bands a peculiar sequence of deposition either on the polarized electrode band and/or on the non-polarized electrode band was observed. An influence of convective diffusion was found to be the reason for such sequence.