Regensburg 2004 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 44: Poster II
HL 44.28: Poster
Donnerstag, 11. März 2004, 16:30–19:00, Poster A
Noise measurements of individual and coupled InAs quantum dots — •P. Barthold1, N. Maire1, F. Hohls1, A. Nauen2, R.J. Haug1, K. Pierz3, and T. Bryllert2 — 1Institut für Festkörperphysik, Universität — 2Div. of Solid State Physics, Lund University, P.O. BOX 118, SE-221 00 Lund — 3Physikalisch- Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig
We present noise measurements of resonant single electron tunnelling through individual and coupled self-organised InAs quantum dots (QDs) at temperatures down to 1.5 K.
In the first case our samples consist of a GaAs/AlAs/GaAs tunnelling structure with self-organised InAs QDs embedded in the AlAs. We investigate the noise generated by the sample with a current amplifier in a range from 0 to 10 kHz, and use a Fast Fourier Transformation analyser for spectral decomposition. Above 1 kHz the noise shows a frequency-independent behaviour indicating the presence of shot noise. Depending on bias voltage we find that the shot noise is suppressed in respect to the Poissonian value 2eI expected for a single barrier. We observe the effect of asymmetric tunnelling barriers on the shot noise suppression. This suppression is characterised by the Fano factor α = S / 2eI whose modulation was perceived in the experiment.
In the second case the sample consists of a GaInAs/InP/GaInAs structure with two layers of self-organised InAs QDs embedded in the InP barrier. We observe definite peaks in the current and a modulations of α as a function of the bias voltage.