Binding of biexcitons in GaAs/${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As superlattices

Properties of the heavy-hole excitons and biexcitons in GaAs/${\mathrm{Al}}_{0.3}$${\mathrm{Ga}}_{0.7}$As superlattices are studied using linear and nonlinear optical techniques. In superlattices with miniband halfwidths less than the exciton binding energy, the biexciton binding energy is found to be the same as in the noninteracting multiple quantum wells of the same width. When the miniband halfwidth exceeds the exciton binding energy, the biexciton binding energy decreases abruptly to the bulk value.