EFFECT OF ELECTRON-HOLE CORRELATION ON ACOUSTIC-PHONON BROADENING OF BOUND EXCITON SPECTRA

It is well-known, experimentally, that bound exciton lines are extremely sharp, particularly in comparison to other related spectra. This has not been theoretically explained. We show here that this is due to the electron-hole correlation, which effectively suppresses the electron-phonon interaction and thus the associated spectral broadening. Using appropriate correlated exciton wave functions together with the deformation potentials and the piezoelectric coupling for the acoustic phonons, we obtain exciton line widths in good agreement with experiment. Our results have direct application to the recently demonstrated blue-green injection laser.