Binding energy of biexcitons and bound excitons in quantum wells

The binding energy of excitons in a semiconductor (e.g., GaAs) quantum well to each other and to neutral donors is calculated variationally using the six-parameter wave function of Brinkman, Rice, and Bell. The biexciton results for wells of various thicknesses agree closely with some of the data previously assigned to the biexciton. The biexciton binding relative to the exciton binding in the two-dimensional limit is about 3-4 times larger than in the three-dimensional case, but otherwise varies in a similar way with the mass ratio. It is found that the biexciton and bound exciton closely obey Haynes's rule.