RESONANT COUPLING BETWEEN BURIED SINGLE-QUANTUM-WELL AND WANNIER-STARK-LOCALIZATION STATES IN A GAAS/ALAS SUPERLATTICE

We have investigated the resonant coupling between the quantized state in a GaAs single quantum well (6.4 nm) buried in the center of a GaAs(3.2 nm)/AlAs(0.9 nm) superlattice and the Wannier-Stark-localization state in the superlattice by using electroreflectance spectroscopy. It is found that the electroreflectance-line shapes of the heavy-hole and light-hole exciton transitions associated with the first (n = 1) subbands in the buried single quantum well drastically change under the resonant-coupling condition: the splitting feature of the line shapes due to the formation of the bonding and antibonding states and the intensity reduction due to the wave-function delocalization over the coupling space. We have detected the various resonant couplings of electrons and holes. The experimental results are discussed from a transfer-matrix analysis with Airy functions.