Symmetry of (formula presented) conduction-band minimum probed by resonant Raman scattering

The nature of the conduction-band minimum of (formula presented) (formula presented) is probed by performing resonant Raman scattering (RRS) on thin layers of (formula presented) epitaxially grown on Ge substrates. Strong resonance enhancement of the LO-phonon Raman intensity is observed with excitation energies near the (formula presented) as well as (formula presented) transitions. However, in contrast to the distinct LO-phonon linewidth resonance enhancement and activation of various X and L zone-boundary phonons brought about slightly below and near the (formula presented) transition, respectively, we have not observed any resonant LO-phonon linewidth broadening or activation of sharp zone-boundary phonons near the (formula presented) transition. The observed RRS results reveal that the conduction-band minimum of (formula presented) predominantly consists of the delocalized GaAs bulklike states of (formula presented) symmetry.