Electroless deposition of Au onto Si(111) studied by surface second harmonic generation

Electroless deposition of Au onto hydrogen-terminated Si(111) from aqueous HF solutions has been studied by Rutherford backscattering (RBS) and in situ surface second harmonic (SH) generation. The SH signal as a function of time goes through a maximum which becomes stronger and occurs at shorter times as the HF concentration is increased. This can be explained through resonant enhancement of the SH signal by the surface plasmon of Au nanoclusters which nucleate at defect sites following deposition and surface diffusion. The initial Au deposition is kinetically limited by diffusion, but growth of Au clusters is kinetically limited by a surface reaction involving a fluoride species. This suggests that Au may be deposited initially in a relatively mobile state which is only partially discharged. (C) 1998 Elsevier Science B.V. All rights reserved.