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.