Corrosion of n-GaAs/aqueous Photoelectrochemical Cell
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A combination of electrochemical studies, scanning electron microscopy, SEM, and light reflectivity measurements reveals information about the corrosion of enlightened n-GaAs in various aqueous electrolytes. The corrosion products influence the electrochemistry of GaAs and thus affect the magnitude of the photogenerated current. It is found that the corrosion products range from the formation of porous layers within GaAs surface region to oxide layers on top of surface depending on the electrolyte composition. Porous layer, forms in HCI solution, enhances the generation of the photocurrent due to decreasing the reflectivity of the incident beam. On the other hand, oxide films deteriorate the photocurrent density, presumably, due to the insulating properties of the oxides. A stable oxide film is formed in an acidic solution of H2O2. The effect of an oxide film on the current -voltage characteristics is investigated. The oxide film thickness is calculated by means of Faraday's law.