4th INTERNATIONAL WORKSHOP ON ELECTRODEPOSITED NANOSTRUCTURES 16-18 March 2006, Dresden, Germany	ABSTRACTS

OPTICAL AND ELECTRICAL PROPERTIES OF ELECTRODEPOSITED CdSe THIN FILMS AS A FUNCTION OF MICROSTRUCTURE D. Karoussos, T. Kosanovic and M. Bouroushian General Chemistry Laboratory, School of Chemical Engineering, National Technical University of Athens 9, Heroon Polytechniou str., Zografos Campus, 157 73 Athens, Greece Variant microstructures of CdSe films (2-3 µm in thickness) were formed by electrodeposition from acidic aqueous solutions under mass transfer control, either by varying the available free energy for the electrosynthetic reaction – through the electrochemical potential control – or by modifying the nucleation and growth conditions through changes in the chemical and physical nature of the deposition substrate. To this purpose, commercial grade Ni and Ti discs were subjected to various pretreatments - in particular chemical etching, anodizing (Ti to TiOx) and buffer layer formation on the metal surface - and used as deposition electrodes under similar electrochemical conditions. The CdSe barrier layers formed on these substrates accommodated different microstructures in terms of crystallite size and microchemical composition. Thermal treatment was applied in certain cases in order to adjust stoichiometry. The morphology of the samples was examined by scanning electron microscopy, while voltammetric, chronoamperometric and current spectroscopy measurements were performed in a proper (photo)electrochemical (PEC) assembly in order to determine their optical and electrical properties. A plain relation between the CdSe film morphology and PEC behavior was established, indicating that the distribution and size of the crystallites cause measurable shifts in the band gap width of the CdSe semiconductor, while determining the photocurrent stability and the resistance to photocorrosion. A particular charge transfer mechanism associated with the existence of a nanostructure was shown to result in higher photoconversion efficiencies than those obtained from larger-grained films.

 
 
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