Surface second harmonic studies of Si(111)/electrolyte and Si(111)/SiO 2/electrolyte interfaces

Abstract

The optical second harmonic (SH) response from Si(111) electrode surfaces has been studied and has been found to be highly potential dependent. For both H-terminated Si(111) surfaces in NH 4F, and oxide-covered surfaces biased in H 2SO 4, the phase and the amplitude display a potential dependence which are attributed to field effects within the semiconductor space—charge region and at the surface of the Si(111) electrode. These studies are the first to demonstrate that for Si(111)/oxide samples, the potential dependence in the SH phase can be correlated with oxide thickness, as demonstrated by examining samples of 0–40 Å thickness.