OBSERVATION OF MINIBAND TRANSPORT IN GAAS AL0.33GA0.67AS SUPERLATTICES/

The low temperature current-voltage characteristics of a strongly coup led, short-period GaAs/Al0.33Ga0.67As superlattice structure have been studied with applied magnetic fields both parallel and perpendicular to the current flow. The complex dependence of the current-voltage cha racteristics on magnetic field perpendicular to the current flow is co nsistent with a simple model based on Bloch transport via the lowest m iniband. From fits to the data the scattering time and mobility have b een estimated as 0.15 ps and 4100 cm(2)/V s, respectively. Further evi dence of negative-differential velocity associated with miniband trans port comes from the observation of an extended negative-differential r esistance region at room temperature in a structure with 50 superlatti ce repeats.