STUDY OF THE INTERACTION AT REST POTENTIAL BETWEEN SILICOTUNGSTIC HETEROPOLYANION SOLUTION AND GAAS SURFACE

In this paper, we demonstrate the possibility of obtaining a modificat ion of GaAs toward the hydrogen evolution reaction (HER) at the rest p otential in an acidic solution of the (SiW12O40)(4-) heteropolyanion ( HPA). This phenomenon is the consequence of a chemical modification of the GaAs surface. The X-ray photoelectron spectroscopy (XPS) results and profile measurements clearly demonstrate that GaAs is oxidised by this Keggin HPA. The constant etching rate is 10 nm h-l. At the same t ime, on the GaAs surface, a deposit is formed that is composed presuma bly of As-0 and WO3. Thus, the Keggin structure (SiW12O40)(4-), usuall y stable, is not preserved on the surface of GaAs. (C) 1998 Elsevier S cience B.V. All rights reserved.