Structural and optical studies of InxGa1-xAs/GaAs multiple quantum wells

Strained multiple quantum wells of Inx Ga12x As/GaAs were grown by low pressure metalorganic chemical vapor deposition ~LP-MOCVD! and characterized by secondary ion mass spectrometry, x-ray diffraction, and optical spectroscopy. The structural analysis demonstrates the excellent control of the interface morphology and composition achieved by MOCVD growth. Temperature dependent optical absorption, photoluminescence, and magnetotransmission were used to evaluate the well-width dependence of the major excitonic properties. The samples show sharp excitonic resonances with distinct excited states evolving into Landau-type excited states in high magnetic field. The well-width dependence of the excitonic eigenstates and of the exciton binding energy as well reproduced by envelope function and variational calculations, also in the presence of external electric field. Finally, nonlinear electro-optic modulation induced by the quantum confined Stark effect is demonstrated in a Schottky diode with extremely low switching threshold.