Wavelength-modulation spectra of GaAs, GaSb, InAs, InSb, Ge, and Si at 5,80, and 300°K are presented. The spectral range extends from 1.75 to 6.0 eV. The results are compared with electroreflectance and thermoreflectance data. New structures are found in the spectra of all crystals. With the help of existing band structures of these crystals, all the reflectivity peaks can be consistently assigned to proper critical transitions between the valence and the conduction bands. Values of spin-orbit splittings at several symmetry points can be calculated. Temperature effects on the band spectra are discussed.

• Received 20 October 1969

DOI:https://doi.org/10.1103/PhysRevB.1.2668