Suppression of exciton-phonon scattering in quasi-one-dimensional systems

Calculations have been made of the linewidth due to LO-phonon scattering of excitons in quasi-one-dimensional (Q1D) systems, which is thought to be the dominant factor in homogeneous broadening of excitonic absorption lines at room temperature. Three kinds of suppression effects for exciton-phonon scattering have been isolated, all of which appear to be achieved in the most pronounced manner in Q1D systems: first by fabricating smaller structures, second by the presence of a Coulomb field between electron and hole in the dissociated exciton, and third by possessing close mass values for electron and hole. It is demonstrated, in particular, as a hypothetical example that an exciton state can be achieved by combining the above effects, which is free from phonon scattering at room temperature.