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We studied the reactivity of GaAs in contact with acidic solutions of, respectively, four heteropolyanions (HPAs): SiW12O404−, SiMo12O404−, PW12O403−, and P2W18O626−. The results obtained by both x-ray photoelectron spectroscopy and etching rate and absorbance measurements showed that GaAs dipped into such solutions undergoes an oxidation/dissolution process while the HPAs are reduced. Indeed, after each immersion of GaAs into an heteropolyanionic solution, a deposit, which consists of As0 atoms with either partially reduced HPA or WO3 is observed. This study has given us the opportunity to determine the reactions which occur at the GaAs/“HPA solution” interface and to point out the importance of the semiconductor energy-band position with respect to the first redox potential of the HPA. Knowledge of the semiconductor/HPA energetic diagram allows one to predict the behavior of HPA species toward semiconductors.

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