Dresden 2003 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 5: Quantenpunkte und -dr
ähte: Transporteigenschaften I
HL 5.1: Vortrag
Montag, 24. März 2003, 10:30–10:45, POT/81
Shot noise in self-organized Quantum Dots — •G. Kießlich1, A. Wacker1, E. Schöll1, A. Nauen2, F. Hohls2, and R.J. Haug2 — 1Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin — 2Institut für Festkörperphysik, Universität Hannover, Appelstr. 2, 30167 Hannover
Shot noise provides a very sensitive tool to probe dynamic correlations of charged particles in tunneling current caused by Coulomb interactions and Pauli exclusion principle. We report the measurement and a theoretical investigation of the low-frequency spectral power density of the current vs. voltage through an ensemble of self-organized InAs quantum dots. The measured Fano factor which characterizes the deviation from the noise for uncorrelated tunneling events (Poissonian noise) shows an average suppression on 0.8. This is associated to the symmetry of the tunneling barriers by the Pauli exclusion principle. By an analytical consideration we find a ratio of the barrier thicknesses of approximately 3/4 which is in good agreement with the sample dimensions. Another interesting feature of the Fano factor is related to steps in the current-voltage characteristic which is believed due to tunneling through few quantum dot ground states. At the steps a Fano factor peak arises. We derive an analytical expression for an arbitrary number of noninteracting states by a master equation model which can reproduce these peaks. Furthermore, the influence of Coulomb interaction on the Fano factor modulation is discussed.