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HL: Fachverband Halbleiterphysik

HL 13: Poster 1

HL 13.51: Poster

Montag, 26. März 2007, 15:00–17:30, Poster A

Noise at a Fermi edge singularity — •N. Maire¹, F. Hohls¹, T. Lüdtke¹, K. Pierz², and R. J. Haug¹ — ¹Institut für Festkörperphysik, Universität Hannover, D-30167 Hannover — ²Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig

We investigate self-assembled InAs quantum dots embedded in a GaAs-AlAs-GaAs heterostructure. We observe distinct steps in the I-V characteristic corresponding to resonant tunneling through individual quantum dots. At high magnetic fields (B>12 T) we measure an additional peak like current overshoot at these steps. The overshoot increases with increasing magnetic field and decreasing temperature. We find that this feature stems from an electron-electron interaction effect between the electron on the dot and the electrons in the lead, a so called Fermi Edge Singularity (FES) effect.

We investigate the noise characteristic at the FES at a magnetic field of 15 T and and at a temperature of 0.4 K. We observe a 1/f and a frequency independent noise, the so called shot noise. The shot noise power is suppressed compared to the noise power of a single tunneling barrier as it is indeed expected for a double barrier resonant tunneling structure. The striking feature is an additional strong suppression of the shot noise power in parallel to the current overshoot induced by the FES effect. We find that this suppression is too strong to be explained by typical theoretical models which do not include the interaction between the lead and the dot.

[1] N. Maire et al., cond-mat/0609738