SHG Measurements of n‐Si(111)/aqueous Solution Interfaces

Abstract

AbstractA study of photoelectrochemical processes at semiconductor electrodes under short‐pulse laser irradiation shows that in‐situ second harmonic generation (SHG) is feasible in such complex interfacial systems. A Nd:YAG laser (532 nm, 7 ns, 40 mW, soft focus 0.2 cm2) was used for SHG in reflection from n‐Si(111) electrodes in a p‐p polarization configuration. We investigated the azimuthal dependence of the SHG at oxide‐covered and bare n‐Si(111) electrodes with and without Ni deposits. The relatively strong SH signal from an oxide‐covered surface originates at the Si/oxide interface. At the bare electrode, the Si/electrolyte interface gives rise to a much weaker signal. Deposition of moderate amounts of Ni on the oxide reduces the SH signal by shadowing the oxide/silicon interface without changing the azimuthal anisotropy. Complete Ni coverage of bare Si leads to a different SH anisotropy.