Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 31: Poster II
HL 31.28: Poster
Dienstag, 26. Februar 2008, 16:30–19:00, Poster D
Magnetization measurements on field-effect induced quantum dots — •G. Stracke1, N. Ruhe1, J. Topp1, S. Mansfeld1, Ch. Heyn1, D. Heitmann1, M.A. Wilde2, and D. Grundler2 — 1Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung der Universität Hamburg, Jungiusstr. 11, D-20355 Hamburg — 2Physik Department E10, Technische Universität München, D-85748 Garching
We have studied the de Haas-van Alphen (dHvA) effect of field-effect induced quantum dots at temperatures down to 300 mK. The dots were formed by depleting a two-dimensional electron system (2DES) with a large-area field-effect electrode. This metallic gate covered in particular a periodic array of PMMA nanocolumns on a modulation-doped GaAs/AlGaAs heterostructure. Each column had a diameter of 280 nm and a height of 120 nm. The dot density was 4.6· 108 cm−2. Using a fiber-optics based magnetometer we measured the dHvA effect as a function of, both, carrier density ns and magnetic field B up to 10 T. The high sensitivity of 4.5 · 10−16 J/T at B=10 T allowed us to detect the dHvA signal for nS ranging from 3.2· 1011 cm−2 in the 2DES down to 20 electrons per dot. In this way, we report for the first time magnetization data which reflect the crossover from a 2D to a 0D electron system.
The authors thank A. Schwarz for experimental support, the DFG for financial support via SFB 508 and the German Excellence Initiative for financial support via the "Nanosystems Initiative Munich (NIM)".