Electric and Magnetic Field Effects on Optical Properties of Excitons in Parabolic Quantum Wells and Quantum Dots

We show how to compute electro- and magneto-optical spectra resulting from the scattering of a plane electromagnetic wave on quantum well (QW) and cylindrical quantum dot (QD) nanostructures with parabolic confinement, in the region of the excitonic resonances. In the case of QWs we consider two configurations of the applied fields: one with both fields perpendicular to the growth planes, the other with both fields parallel to the QW planes. In the first case we observe how the diamagnetic shift and the Stark shift influence the shape and the positions of the excitonic peaks. For both fields parallel to the plane we observe Franz-Keldysh oscillations above the Landau states. In the case of cylindrical QDs we consider the effects of the magnetic field applied parallel to the symmetry axis and the electric field applied perpendicular to it. Again we observe displacements of the peaks and the variation of the peak hights depending on the relative strengths of the fields. Results are given for In_xGa_1—xAs/InP QWs, and cylindrical In_xGa_1—xAs/GaAs and GaAs/Ga_1—xAl_xAs QDs. Fair agreement with experiments is obtained.