Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 9: Poster I
HL 9.78: Poster
Montag, 27. März 2006, 15:15–17:45, P3
Shot noise at a Fermi edge singularity — •N. Maire1, T. Lüdtke1, F. Hohls1,2, R. J. Haug1, and K. Pierz3 — 1Institut für Festkörperphysik, Universität Hannover, D-30167 Hannover — 2Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, UK — 3Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig
We investigate self-assembled InAs quantum dots embedded in a GaAs-AlAs-GaAs heterostructure. We see steps in the I-V characteristic which can be directly linked to resonant tunneling through individual quantum dots. At one of these steps we notice a peak like current overshoot at a magnetic field of 14.9 T. We find that this current overshoot stems from an electron-electron interaction effect, a so-called Fermi edge singularity (FES) effect.
We measure the noise spectra of this step and observe a 1/f noise and a frequency independent noise, the shot noise. We observe a suppressed shot noise compared to the theoretical value S=2eI of a single tunneling barrier. This suppression is indeed expected for a double barrier resonant tunneling structure (DBRTS). This suppression is characterized by the dimensionless Fano factor α =S/2eI; S being the average noise power density. We find that the shot noise is even more suppressed at the voltage position of the current peak induced by the FES. Temperature dependent measurements down to ≈ 300 mK show that this additional suppression decreases with increasing temperature. We find that these effects can be attributed to the varying tunneling rate of the emitter electrons near the FES.