Sequential tunneling current through semiconductor superlattices under intense THz radiation

Recent transport measurements in GaAs–GaAlAs superlattices under THz radiation show evidence of dynamical localization and electron pumping in the opposite direction to the dc bias in the linear response regime. The ac field induces absorption and emission processes in the multiwell structure which assist the tunnel and which are reflected as new features in the current density. A calculation within the framework of the Bardeen Hamiltonian has been performed to evaluate the tunneling current through the superlattice in the presence of an ac field. By means of this model these new features are reproduced in the current which can be explained in terms of the new induced tunneling channels and of the charge occupation in the wells. © 1997 American Institute of Physics. @S0003-6951~97!00726-2#