Regensburg 2002 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 2: Transporteigenschaften
HL 2.7: Vortrag
Montag, 11. März 2002, 12:00–12:15, H13
Effective mass engineering in two-dimensional electron systems subject to a strong short-period modulation — •C. Pflügl1, R. Deutschmann2, F. Ertl2, W. Wegscheider1, M. Bichler2, and G. Abstreiter2 — 1Universität Regensburg, Institut für Experimentelle und Angewandte Physik, 93040 Regensburg — 2Walter Schottky Institut, Technische Universität München, Am Coulombwall, 85748 Garching
We investigated the Fermi energy dependence of the effective mass in a two-dimensional electron system subject to a strong, atomically precise one-dimensional AlGaAs/GaAs superlattice potential fabricated by the cleaved-edge-overgrowth technique. With temperature dependent magnetotransportmeasurements we were able to confirm the selfconsistently calculated effective mass in the first miniband as well as in the band gap by raising the Fermi energy by means of the gate. Magnetotransport also reveals the different behavior of electrons in the miniband, characterized by closed orbits and magnetoresistance oscillations, and in the band gap, manifested by open orbits and quenching of the magneto quantum oscillations. For large magnetic fields, closed orbits are rediscovered due to magnetic breakdown. These measurements also reveal the difference between the quantum and the transport scattering time that can be explained by the influence of the highly doped GaAs-Gate.