Hamburg 2001 – scientific programme
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HL: Halbleiterphysik
HL 7: Poster I
HL 7.63: Poster
Monday, March 26, 2001, 10:30–19:00, Rang S\ 3
Preparation and characterization of GaAs/AlGaAs quantum point contacts and short quantum wires — •Gabriela Apetrii1, S. Skaberna1, U. Kunze1, D. Reuter2, and A.D. Wieck2 — 1Lehrstuhl für Werkstoffe der Elektrotechnik, Ruhr-Universität Bochum, Universitätsstr. 150 IC2, D-44780 Bochum — 2Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum
An atomic force microscope (AFM) was used to prepare quantum point contacts (QPCs) and short quantum wires (QWRs) from a two-dimensional electron gas in a GaAs/AlGaAs heterostructure. Using the tapping mode of the AFM the tip plows a furrow into a thin resist layer. Transfer of the resist pattern into the semiconductor substrate is achieved by subsequent wet-chemical etching resulting in 50 nm wide grooves, which define a ballistic constriction of 50-170 nm width or a 60 nm wide and 130-430 nm long QWR. At 4.2 K the conductance characteristics of QPCs exhibit a stepwise increase in units of 2e2/h with broad plateaus. Both the occurrence of quantized conductance and the plateau width depend on the applied voltage during the cooling process. While the 130 nm QWR shows wide conductance plateaus those of the longer QWRs are strongly distorted. We also discuss deviations of the quantized conductance from multiples of 2e2/h.