Exciton binding energy in type-II GaAs-(Al,Ga)As quantum-well heterostructures

The binding energy of the ground-state exciton is calculated variationally for the GaAs-(Al,Ga)As system when the band-edge configuration at the heterojunction has become staggered or ``type II.'' Anisotropy in both the hole and electron effective masses is considered and calculations are performed assuming perfect confinement of both sorts of carriers. The binding energies we calculate are of a similar magnitude to those found for the 1s heavy-hole (or 1s light-hole) exciton in this system when the configuration is the more familiar straddled of type-I arrangement.