DERIVATIVE SPECTRUM OF INDIRECT EXCITONS IN ALSB

Structure due to phonon-assisted exciton transitions has been observed in AlSb at 77°K using a double-beam wavelength modulation spectrometer. The exciton energy gap and the energies of the TA, LA, and LO Phonons at the X-point of the Brillouin zone have been determined. These results are consistent with the valence and conduction band extrema having Γ15 and X1 symmetries respectively. The systematics of the phonon energies at the X point of zinc-blende-type materials is discussed. © 1969.