EXCITON-PHONON COUPLING IN INDIRECT ALXGA1-XAS

Several persistent high-energy peaks in the photo-luminescence spectrum of indirect AlxGa1-xAs are reported. These transitions are assigned to zero-phonon and phonon-assisted bound-exciton annihilation processes. Symmetry determined selection rules indicate that the major interband recombination mechanism is due to LO phonon scattering of electrons near X(100) to the energetically adjacent ΓCB1 (000) intermediate state. Scattering associated with alloy disorder may also contribute to the spectrum. The change in the phonon-assisted spectra at x = 0.43 ± 0.01 provides an additional means of identification of the direct-indirect conduction band crossover. © 1979.