Effects of confined longitudinal and interface optical phonons on excitons in an asymmetric quantum well

The interaction between exciton and confined longitudinal optical (LO) phonons, interface optical (IO) phonons in an asymmetric Ga 1 x Al x As/GaAs/Ga 0.7 Al 0.3 As square quantum well is investigated. By applying the LLP-like transformation and variational approach, the numerical results are obtained as functions of the well width and asymmetric-degree of well. The exciton-optical phonons interaction-energy has a minimum value with the increase of the well width. It is demonstrated that the LO-phonon energy-contribution increases while the IO-phonon contribution decreases as the well width increases gradually The energy-contribution of LO-phonon in symmetric and asymmetric square quantum well does not have too much difference but the IO-phonon contribution varies apparently. The exciton binding-energy monotonically decreases with the increase of the well width and is proportional to the left-barrier height.