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Dresden 2003 – scientific programme

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HL: Halbleiterphysik

HL 34: Transporteigenschaften

HL 34.9: Talk

Wednesday, March 26, 2003, 18:45–19:00, POT/81

Experimental tunneling between parallel 1D quantum wires and adjoining 2D electron reservoirs — •S. Roth, F. Ertl, D. Schuh, M. Bichler, and G. Abstreiter — Walter Schottky Institut, Technische Universität München, Am Coulombwall, D-85748 Garching

The cleaved-edge overgrowth method allows to realize low-dimensional nanostructures with a variety of possible geometries in atomic precision. Therefore we succeeded to fabricate GaAs/AlGaAs devices, in which we study lateral tunneling between large 2D electron reservoirs and one or more parallel 1D quantum wires. The electrostatically induced 2D system of a 750nm long vertical transistor is split by a few 3nm wide AlAs barriers with a distance of 12nm, which confine the 1D states. Self-consistent solutions of the Schrödinger-Poisson equations show clearly the 1D/2D systems in the probability distribution. We characterize these tunneling devices at 4.2K by measuring the I-V curves under gate voltage bias Vg. The I-V traces exhibit regions of negative differential resistance and weaker resistance changes, which we attribute to tunneling resonances. Due to the peculiar transistor geometry, the fingerprint of the tunneling structure is visible only at large Vg and small V. Concerning that part of the Vg-V phase space we observe: First, that the resonances are nearly independent of Vg. Second, that the resonance voltage V marginally varies with the number of involved quantum wires. We propose that allmost all source-drain voltage drops over the first barrier at the 2D-1D transition and only a small amount at the 1D-1D transitions. Our experimental findings are explained well by a model based on this assumption.





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