Coordination chemistry of semiconductor photoelectrodes: reactions of etched n-gallium arsenide with cobalt(III) complexes

Abstract

We report studies of the reactivity of n-GaAs surfaces with transition-metal complexes. Generally, adsorption of metal ions at semiconductor junctions has been observed to increase carrier trapping rates. A notable exception is the improved performance of n-GaAs interfaces after exposure to acidic aqueous solutions of Ru(III) ions and other metal cations, but little information is available regarding the chemistry of these surface treatments. Except for systems in which metal ions act as precursors for the deposition of metals or metal alloys, no information is available regarding the oxidation state or chemical environment of chemisorbed transition-metal complexes on semiconductor electrodes. Possible but undocumented mechanisms of metal ion attachment to the semiconductor surface include electrostatic binding, ligand substitution processes, and redox reactions. To explore the various possible modes of reaction, we have investigated the chemistry of n-GaAs surfaces in contact with aqueous solutions of Co(III) complexes.

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