Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 31: Poster I: Devices, Quantum Dots and Quantum Wires
HL 31.31: Poster
Dienstag, 23. März 2010, 18:30–20:30, Poster D1
Quantum point contacts in quantum wire systems — •E. Sternemann1, S.S. Buchholz1, S.F. Fischer1, U. Kunze1, D. Reuter2, and A.D. Wieck2 — 1Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum — 2Angewandte Festkörperphysik, Ruhr-Universität Bochum
Quantum point contacts (QPCs) attract high interest for applications as magnetic focussing, beam splitting (quantum Hall edge states), spin filtering and electron thermometry. Here, we investigate QPCs in complex quantum wire (QWR) systems such as quantum rings. The QPCs were realized by lithographical definition of a short (150 nm) constriction (170 nm width) in (a) a 540 nm wide QWR and (b) 520 nm wide QWR leads of a QWR ring as in [1]. Nanogates on top of the constrictions allow for the control of occupied modes in the QPCs. The devices are based on a GaAs/AlGaAs heterostructure with a 2DEG 55 nm below the surface, patterned by electron beam lithography and wet-chemical etching. Two- and four-terminal conductance measurements at temperatures between 23 mK and 4.2 K were performed using lock-in technique. Our measurements reveal that QPCs in 1D nanostructures can be prepared to show subband separations of 6 meV, clear conductance quantization as well as the 0.7 anomaly. We further show that electron injection across a QPC into a QWR ring allows for electron interference (Aharonov-Bohm effect).
[1] S.S. Buchholz, S.F. Fischer, U. Kunze, D. Reuter, A.D. Wieck, APL 94, 022107 (2009).