WANNIER-STARK QUANTIZATION AND ITS APPLICATIONS TO ELECTROOPTICAL MODULATION

An external electric field applied parallel to the growth axis of a semiconductor superlattice produces a localization of the eigenstates and a quantization of the energy spectrum. These effects, which we have named Wannier-Stark quantization, are not only remarkable from the point of view of fundamental physics, they also have a good potential for various applications in opto-electronics. Indeed, the superlattice electro-absorption shows both a blue shift associated with the "decoupling" of the quantum wells and, at very low field, a red shift associated with the existence of transitions "oblique in real space" between states localized near adjacent quantum wells. Both effects have been observed at room temperature, and have led to outstanding device performances. © 1990.