Photoelectrochemical properties of n-GaAs/ITO electrodes produced by dc sputtering

Coating of n-GaAs with transparent conductive films, such as ITO (indium tin oxide), should protect this material against photodecomposition. n-GaAs/ITO samples were produced by reactive de sputtering using pure oxygen as the reactive sputtering gas. The electrochemical and photoelectrochemical properties of these devices were investigated in different aqueous electrolytes. The cyclic voltammograms of n-GaAs/ITO devices show increasing photocurrent with increasing scan number. This general behaviour can be explained by a corrosion of the ITO film as well as of the n-GaAs substrate. Thus, the produced samples show only low time stability for use as photoelectrodes. An explanation for this behaviour is given.