The valence band structure of the III–V compounds

Abstract

Absorption bands due to intervalence band transitions have been observed in p-type AISb and GaAs. In GaAs, three bands at 0·42 eV, 0·31 eV, and 0·15 eV are identified as transitions between : the split off valence band and the heavy-hole band, the split off valence band and the light hole band, and the light- and heavy-hole bands respectively; the spin-orbit splitting of GaAs is 0·33 eV at k = 0. In AISb, the bands at 0·75 eV and 0·15 eV are identified with transitions between the split off valence band and the heavy-hole band, and the light- and heavy-hole bands respectively; the AISb spin-orbit splitting at k = 0 is 0·75 eV. The spin-orbit splittings of all the III–V compounds are estimated using a simple model which employs the free atom spin-orbit splittings of the constituent atoms of the compounds. The observed splittings of GaAs, AISb, and other III–V compounds are in agreement with this model. The conduction and valence band effective masses at k = 0 of the III –V compounds derived from k.p. theory for the band structure of the zincblende semiconductors are shown to be consistent with available experimental data.