ATOMICALLY PRECISE SUPERLATTICE POTENTIAL IMPOSED ON A 2-DIMENSIONAL ELECTRON-GAS

We have been able to fabricate a two-dimensional electron gas containing an atomically precise, lateral Kronig-Penney potential of 102 angstrom periodicity. The structure was formed by modulation-doped molecular beam epitaxy overgrowth on the cleaved edge of a 71 angstrom GaAs/31 angstrom AlGaAs compositional superlattice. Low-temperature magnetotransport reveals clear quantum Hall characteristics. From the onset of the Shubnikov-de Haas oscillations at 0.25 T we deduce a lower limit of the mobility of mu > 40 000 cm2/V s at an electron density of 3.0 x 10(11) cm-2 and infer that the carriers are crossing more than 200 GaAs/AlGaAs interfaces without losing phase coherence.