Regensburg 2004 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 37: Quantenpunkte und -drähte: Transporteigenschaften
HL 37.12: Vortrag
Donnerstag, 11. März 2004, 13:00–13:15, H13
Shot noise measurements of InAs quantum dots — •N. Maire1, A. Nauen1, F. Hohls1, R. J. Haug1, and K. Pierz2 — 1Institut für Festkörperphysik, Universität Hannover, D-30167 Hannover — 2Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig
We investigate the noise properties of self-assembled InAs quantum dots embedded into a GaAs-AlAs-GaAs heterostructure. The I-V-characteristic shows a step-like dependence which can be directly linked to resonant tunneling through the ground states of single quantum dots. This allows us to measure the noise properties of single 0-dimensional states.
The resulting noise power shows a frequency independent spectrum from 1-10 kHz, the so called shot noise. This noise power is suppressed compared to the theoretical value 2eI of a single tunneling barrier as it is indeed expected for a double barrier resonant tunneling structure. This suppression is characterized by the dimensionless Fano factor α =S/2eI; S being the average noise power density. Measurements at high magnetic fields show a transition from a single step to a double step in the I-V- characteristic due to Zeeman splitting and a shifting of α as a transition from a spin nondegenerate ground state to a degenerate ground state occurs. Furthermore the temperature dependence of α on the Fermi occupation function of the emitter is observed.