Electroreflectance at a Semiconductor-Electrolyte Interface

Abstract

The electroreflectance spectra of Si, Ge, $\ensuremath{\alpha}$-Sn, AlSb, GaP, GaAs, GaSb, InP, InAs, InSb, ZnO, ZnTe, CdS, CdSe, and CdTe are reported. The measurements were performed by the electrolyte technique in the 1-to 6-eV photon energy range. The data were processed by the Kramers-Kronig technique and the variation in ${\ensuremath{\epsilon}}_{1}$ and ${\ensuremath{\epsilon}}_{2}$ induced by the applied electric field obtained. Several sharp peaks were observed in all these spectra and interpreted in terms of critical points in the joint density of states for optical transitions. As a result, a large number of direct interband energy gaps and spin-orbit splittings is obtained. These spin-orbit splittings are interpreted and correlated by using the k. p method: Enough experimental information is available to determine the effects of spin-orbit interaction on the valence bands of most of these materials at any point in k space.