Longitudinal optical phonon replica of free exciton in GaAs

Longitudinal optical (LO) phonon replica of free exciton in pure GaAs has been studied at 50K by means of resonance excitation at n=1 free exciton state and 900 scattering spectroscopy. From the phonon assisted exciton recombination photoluminescence, the LO-phonon energy is obtained to have a discrete value of 36.7 +- 0.2meV and it is learned that the 1-LO phonon replica might project the free exciton distribution being in the form of Esup(3/2) exp(-E/ksub(B)T). Also noticable are the fact that the n=2 free exciton state, which fails to show any response at zero-phonon emission spectra, may be observable on 1-LO and even 2-LO phonon replicas. (author)