The excitonic states have been investigated in In0.045Ga0.955As/GaAs heterostructures consisting of i quantum wells (i= 1,2,3,4) with 7.5 nm well thickness. For a 2.5 nm barrier thickness between the wells, the electronic states are strongly coupled. Because of the coupling, the heavy-hole exciton nshh of each single quantum well is split into i2 states. The states can be characterized according to their symmetry under a combination of the reflections of the single particles at the quantum-well plane. The energy order of the symmetric and antisymmetric states as a function of quantum-well number is investigated in detail, and compares well to the theoretical calculation. These coupled quantum-well structures exhibit somewhat three-dimensional character based on the study of their exciton binding energies and wave functions. Highly resolved photoluminescence excitation spectra are presented, measured in magnetic fields up to 13 T using circularly polarized light. Strong mixing between light- and heavy-hole excitons causes optical transitions into high-angular-momentum exciton states and strong anticrossing effects. An anticrossing between the 3dhh11 and hh21 exciton is observed. Also, the light-hole exciton is found to possess Γ7g and Γ6g symmetries.
|Number of pages||7|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 15 Sep 2000|