DIRECT INVESTIGATION OF LOCALIZED HOLE STATES IN PSEUDOMORPHIC MODULATION-DOPED ALXGA1-XAS INYGA1-YAS/GAAS HETEROSTRUCTURES BY OPTICAL-DETECTION OF QUANTUM OSCILLATIONS/

The valence-band structure in AlxGa1-xAs/InyGa1-yAs/GaAs heterostructu res (x=0.2, y=0.1) is inves tigated using a magnetic method for probin g the electronic structure in two-dimensional (2D) heterostructures th rough the optical detection of quantum oscillations (ODQO). For struct ures with narrow InyGa1-yAs quantum wells (W<15 nm), the quantum oscil lations with the Fermi sea reveal two distinct periods in 1/B. This be havior is attributed to the existence of two classes of hole localizat ion: a shallow one, primarily resulting in hole scattering, and a deep localization resulting in a 10-meV shift in the ODQO. In wider InyGa1 -yAs quantum wells (W=15 nm), where the two-period behavior begins to disappear, excitonic luminescence is observed in addition to the 2D-el ectron features. This excitonic contribution strongly modifies the dev elopment of photoluminescence signature into Landau-level fan.