Magnetotransport investigations of structural irregularities in a weakly coupled GaAs/AlAs superlattice under domain formation

Irregular current branches have been observed experimentally in the I-V cha racteristics, when static electric-field domains are formed in a weakly cou pled GaAs/AlAs superlattice. The origin of these irregularities has been in vestigated by applying a magnetic field B perpendicular to the layers. With increasing B, the maximum value and the width of different current branche s become more and more regular. At B=9 T, most current branches are extreme ly regular;indicating that the irregularities are induced by scattering pro cesses, which determine the current in the nonresonant tunneling regime. Ho wever, some branches are not affected by the magnetic field demonstrating t hat they are completely induced by the deviation from an ideal periodicity or by the inhomogeneities at the contact.