Dresden 2003 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 34: Transporteigenschaften
HL 34.9: Vortrag
Mittwoch, 26. März 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.