Berlin 2005 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 45: Quantenpunkte und -dr
ähte: Transporteigenschaften II
HL 45.4: Vortrag
Montag, 7. März 2005, 15:45–16:00, TU P-N202
Mode coupling of spatially coincident electron wave guides — •S.F. Fischer1, G. Apetrii1, U. Kunze1, D. Schuh2, and G. Abstreiter2 — 1Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum, D-44780 Bochum — 2Walter Schottky Institut,Technische Universität München, D-85748 Garching
Mode coupling phenomena in electron wave guides lead to wave function mixing and splitting of degenerate one-dimensional (1D) energy levels. The direct experimental determination of splitting energies demands coherent ballistic electron transport and high 1D-subband spacings (>10 meV). Nanolithography with an atomic force microscope enables us to prepare spatially coincident 1D electron systems which meet these requirements and for which massive wave function mixing is expected. Quantum point contacts were fabricated from a modulation doped GaAs/AlGaAs system with a 30 nm wide square quantum well with two occupied 2D subbands. We find a rich mode spectrum by recording transconductance maxima at 2 K as a function of gate voltage and magnetic field. Magnetotransport spectroscopy of unprecedented resolution allows the proper identification of heretofore unresolved subtle interference induced by mode coupling. Imaging the of transconductance vs. drain- and gate voltage enables the direct determination of splitting energies (> 2 meV).