Magnetotransport measurements on overgrown cleaved edge heterostructures in Hall bar geometry

摘要

We present new methods to pattern and characterize the overgrown cleaved egde (CE) of GaAs/AlGaAs heterostructures. Four point measurements, which allow a direct measurement of the magnetotransport coefficients p(xx) and p(xy) of a two-dimensional electron system on the CE, have been out of reach so far. By means of novel preparation techniques a contacted Hall bar structure can be created on the edge of the cleavage plane. The potential of the new method is first tested on a system which is density modulated in a direction parallel to the current flow due to an underlying GaAs/AlGaAs superlattice. To create a two-dimensional electric modulation we managed to pattern the active area of the Hall bar with periodically arranged lines in the direction perpendicular to the MBE-grown superlattice. The resulting unit cells are reflected in magnetoresistance oscillations associated with the most prominent one-dimensional Fermi contours along x- and y-direction. (c) 2006 Elsevier B.V. All rights reserved.