Authors: ECKEHARD SCHOLL
Abstract: Electro-optical effects, such as the Franz-Keldysh effect in bulk materials or the quantum confined Stark effect in quantum well structures, lead to strong optoelectronic nonlinearities which form the basis for optical modulators and optically bistable devices. They result from a modification of the optical absorption properties by an applied electric field and are particularly pronounced in the case of low dimensional semiconductors. We review theoretical modelling and computer simulations of such optoelectronic devices in particular for ZnSe based quantum well structures, where excitonic features dominate even at room temperature. The field dependent absorption spectra are calculated by a many-body theory including the full electron-electron interaction. The transition from the quantum confined Stark effect, which is found for well widths smaller than the exciton Bohr diameter, to the Franz-Keldysh effect, which corresponds to the limit of wide wells, is studied. Optical bistability and switching is found in R-SEED and D-SEED configurations, and the optimization of the device performance is discussed.
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