In situ second harmonic generation measurements during the electrodeposition of Ni on n-Si(111)

Abstract

Reflection measurements of optical in situ second harmonic generation (SHG) from n-Si(111) electrodes in contact with various aqueous electrolytes under potentiostatic control in an electrochemical cell are presented. Special attention was payd to both oxide-free and oxide-covered surfaces, and, particularly, to the electroplating of Ni on Si/SiO 2. A SiO 2-covered surface yields a SH signal by an order of magnitude higher than the bare Si surface. The SH azimuthal anisotropy reflects the C 3v symmetry of the (111) silicon plane superimposed by an additional mirror plane which may be explained by surface step arrays due to slight misorientation of the (111) surface. With electrodeposited Ni coverage on the oxidized surface, the SH signal decreases, probably due to shadowing without substantially changing the symmetry. These facts point to the SHG originating from the Si/SiO 2 interface.