Exciton linewidth in semiconducting quantum-well structures.

TLDR: The exciton linewidth has been calculated in semiconducting quantum-well structures as a function of the width of the well when the electron-hole pairs which are bound into the exciton are scattered by polar optical phonons; the numerical value is in good agreement with the experimentally observed value.

Abstract: The exciton linewidth has been calculated in semiconducting quantum-well structures as a function of the width of the well when the electron-hole pairs which are bound into the exciton are scattered by polar optical phonons. The linewidth for this scattering mechanism is found to increase as the width of the well decreases; therefore confinement of the exciton in a quantum-well structure will increase the linewidth of the exciton peaks when the exciton is scattered by polar optical phonons. The dominant contribution to the linewidth comes from processes in which the exciton is ionized into a free electron-hole pair by the absorption of a polar optical phonon. The numerical value we calculate for the linewidth is in good agreement with the experimentally observed value in GaAs/${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Al}}_{\mathrm{x}}$As quantum-well structures.