The binding energy of bi-excitons which were bound to single-island interface defects in deep quantum-wells was calculated. The use of a variational function led to calculations that were largely analytical. The dependence of the bi-exciton binding energy upon the defect size and the quantum-well width was considered in detail. Numerical calculations were carried out for AlGaAs/GaAs quantum wells with defect depths of 1 or 2 mono-layers. An attempt was made to correlate the present case, of a localized bi-exciton, with existing results for free 4-particle molecules in various confinement structures and for various mass ratios.

O.Heller, P.Lelong, G.Bastard: Physical Review B, 1997, 56[8], 4702-9