X 1 and X 3 states of electrons and phonons in zincblende type semiconductors

Abstract

Despite the extensive experimental and theoretical characterization of the band structures of III–V zincblende semiconductors, the literature is still ambiguous in classifying the symmetries of the lowest conduction states at the X point in the Brillouin zone of these compounds. We present the symmetries of these states obtained by the first principles pseudopotential and the LMTO methods and consistently label them for this class of compounds. We also point out that analyses of the indirect optical absorption edge structure in compounds with lowest conduction states at X like AlAs, AlSb and GaP reveal the symmetries of these states in agreement with theoretical predictions. This technique could also be used to determine these symmetries in other indirect gap compounds or those which acquire an indirect gap Γ → X under reasonably modest pressures like GaAs.