Fundamental Reflectivity Spectrum of Semiconductors with Zinc-Blende Structure

Abstract

The fundamental reflectivity spectrum of several III–V and II–VI semiconductors is discussed and compared with the reflectivity spectrum of the group IV semiconductors. A general feature of these spectra is the presence of two peaks within the fundamental absorption region. The lower energy peak, which corresponds to a maximum in the refractive index, can be split into a doublet. This peak is probably due to direct transitions between the valence band extrema in the [111] direction at the edge of the Brillouin zone (L point) and the corresponding conduction band minima. The splitting of this peak corresponds to the spin-orbit splitting of the valence band extrema (L3). The second peak corresponds to a maximum in the combined density of states for the transitions. The temperature dependence of these peaks is also discussed.