Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 58: Poster IIb

HL 58.60: Poster

Dienstag, 8. März 2005, 16:30–19:00, Poster TU F

Nanolithography on AlGaAs-GaAs heterostructures by Atomic Force Microscope — •Kevin Rachor, Steffen Groth, Christian Heyn, Detlef Heitmann, and Can-Ming Hu — Institut für Angewandte Physik , Universität Hamburg, Jungiusstr. 11, 20355 Hamburg

We have explored two different techniques to pattern AlGaAs-GaAs heterostructures with a two dimensional electron gas (2DEG) confined 35 nm below the surface by AFM: (i) The "dynamical ploughing", where the AFM tip scribes a pattern into a very thin photoresist on top of the sample and the pattern is transferred by wet chemical etching into the AlGaAs. (ii) We have also performed local anodic oxidation with a bias voltage between tip and sample. Both methods yield a depletion of the 2DEG underneath, respectively, the etched or the oxidized lines. We fabricate ballistic quantum point contacts (QPC’s) with geometrical width between 50 and 150 nm. Conductance measurements at 4.2 K are performed, which can demonstrate the formation of 1D subbands in the QPC’s by varying the electron density using a top gate.