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HL: Halbleiterphysik

HL 30: Quantum dots and wires: Transport properties II

HL 30.1: Vortrag

Mittwoch, 29. März 2006, 18:15–18:30, HSZ 01

Tunnel-coupled one-dimensional electron systems — •S.F. Fischer¹, G. Apetrii¹, U. Kunze¹, D. Schuh^2,3, and G. Abstreiter³ — ¹Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum, D-44780 Bochum — ²Walter Schottky Institut,Technische Universität München, D-85748 Garching — ³Angewandte u. Exp. Physik, Universität Regensburg, D-93040 Regensburg

Wave function mixing and splitting of degenerate one-dimensional (1D) energy levels are a direct outcome of tunnel coupling between 1D ballistic electron systems. We present the conductance and transconductance measurements of vertically stacked short electron wave guides fabricated from tunnel-coupled quantum wells in GaAs/AlGaAs heterostructures with atomic force microscope lithography [1]. Subsequent 1D subbands are populated by increasing a top gate voltage. The subladders of the top and bottom electron wave guides can be shifted relative to each other by application of a back gate voltage [2], magnetic fields or cooling under top gate bias [3]. Mode coupling is reflected by level anti-crossings. Large 1D-subband spacings (>10 meV) allow an unprecedented resolution in drain bias spectroscopy which proves as a powerful tool for the direct determination of splitting energies. Device operation above liquid helium temperature is demonstrated. In an outlook we compare vertically and laterally tunnel-coupled 1D electron systems.

[1] U. Kunze, et al., Superlatt. Microstructures 31 (2002) 3.

[2] G. Apetrii, et al.,Physica E, in press.

[3] S.F. Fischer, et al.,Appl.Phys.Lett. 81 (2002) 2779.