MAGNETOOPTICAL PROPERTIES OF BIAXIALLY STRAINED QUANTUM-WELLS

We have studied the optical properties of GaAs1-xPx/Ga0.65Al0.35As qua ntum wells as a function of well width and phosphorus concentration in the presence of an external magnetic field. The combination of confin ement and lattice-mismatch effects in this system allows tuning of the splitting between the heavy-hole and light-hole subbands. The ground- and excited-state energies of the excitons are obtained from low-temp erature photoluminescence excitation spectroscopy. From an analysis of the fan diagrams, using a two-dimensional hydrogenic model, we have d etermined the binding energies and the reduced effective masses of the heavy-hole and light-hole excitons. An enhancement of the effective m asses of the holes is observed as the heavy- and light-hole subbands a pproach. An unexpected behaviour of the degree of polarization of the excitons with increasing magnetic field is also observed.