Staggered excitonic resonances of Stark-ladder transitions in an asymmetric double-well GaAs/AlAs superlattice

Excitonic effects on Stark-ladder transitions have been investigated experimentally and theoretically in a novel asymmetric double-well superlattice consisting of wide and narrow GaAs quantum wells separated by a constant AlAs barrier. In this superlattice strong electron resonance can occur under the applied electric field between the wide and narrow wells. It is found that due to existence of the two different heavy-hole localized states two types of excitonic resonances which are staggered in field are observed in the low-temperature photocurrent spectra. This field difference in the staggered exciton resonances is rigorously explained by variational calculations of the changes in the direct and indirect exciton binding energies with the field.