Tunneling and nonlinear transport in a low-dimensional vertically coupled GaAs/AlGaAs system

We report low-dimensional tunneling in an independently contacted vertically coupled quantum wire system. This nanostructure is fabricated in a high-quality GaAs/AlGaAs parallel double quantum well heterostructure. Using a novel flip chip technique to align top and bottom split gates to form low-dimensional constrictions in each of the independently contacted quantum wells we explicitly control the subband occupation of the individual wires. Our designed geometry includes simultaneous measurement of both the 2D-2D and 1D-1D tunneling regimes. In addition to the expected 2D-2D tunneling results, we have found additional tunneling features that are related to the 1D quantum wires. © 2006 Elsevier B.V. All rights reserved.