Dresden 2003 – scientific programme

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HL: Halbleiterphysik

HL 49: Poster II

HL 49.21: Poster

Thursday, March 27, 2003, 16:30–19:00, HSZ/P2

Transport through few electron quantum dots — •Michael Tews and Daniela Pfannkuche — 1. Institut für Theoretische Physik, Universität Hamburg, Jungiusstr. 9, 20355 Hamburg

We report on transport calculations through a spherical semiconductor quantum dot occupied by few electrons based on the Real-Time Transport Theory developed by Schoeller et al. [1]. Coulomb interaction within the quantum dot is fully taken into account by diagonalizing the dot Hamiltonian. We study the differential conductance in the regime of weak and intermediate coupling to the connecting leads for different electron-electron interaction strength.

Transport is dominated by sequential tunneling processes in the weak coupling regime and tunneling rates are described by Fermi’s golden rule. They essentially reproduce the spectral weights assigned to a particular transport channel. Strongly correlated quantum dot states are characterized by small spectral weights. Their occupation leads to channel blocking in non-linear transport and as a consequence to characteristic negative differential conductance. On the other hand correlations are expected to play a less important role in the regime of intermediate coupling. In order to study transport in this regime co-tunneling processes are included.

[1] Herbert Schoeller and Gerd Schön, Phys. Rev. B 50, 18436 (1994)