ABOVE BARRIER EXCITON CONFINEMENT IN INGAAS/GAAS MULTIPLE-QUANTUM-WELL STRUCTURES

Exciton confinement in the GaAs barriers of InGaAs/GaAs multiple-quantum-well structures is demonstrated by luminescence self-absorption and photoluminescence excitation spectroscopies. The confinement energy and absorption linewidth depend on the barrier width as predicted by a plain quantum mechanical model. For thin barriers, a splitting in the experimental lineshape is accounted for by including into the theoretical model the interaction among excitons confined in individual barriers. Evidence for a transition between a hole state in the well and an electron state confined in the barrier is also reported, which provides a direct way for estimating the band offsets.