ELECTRONIC-SPECTRUM OF QUANTUM-DELTA-WELLS SUPERLATTICES IN AN ELECTRIC-FIELD

We study one-dimensional periodic chains of quantum 6 wells, centering our attention on the properties of the electronic spectrum in the pre sence of an electric field. We study the field dependence of the quasi bound and resonant states of the system, which we define clearly. The spectrum, whose absolute behavior depends on the symmetry of the poten tial, is universal if an appropriate origin of energy is chosen. The f ield finally transforms the spectrum into a continuous one. We study a lso the formation of Wannier-Stark ladders. Finally, we show that in s uperlattices, the quasibound levels are never degenerate.