Regensburg 2013 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 91: Poster Session: Quantum dots and wires: preparation & characterization & optical properties & transport properties

HL 91.31: Poster

Donnerstag, 14. März 2013, 16:00–20:00, Poster A

Single-particle-reduced entropy for few-electron states in gated semiconductor nanowires — •Jose Maria Castelo¹, Klaus Michael Indlekofer¹, and Joerg Malindretos² — ¹RheinMain University of Applied Sciences, IMtech / Faculty of Engineering, D-65428 Rüsselsheim, Germany — ²Georg-August-Universität Göttingen, IV. Physikalisches Institut, D-37077 Göttingen, Germany

We consider electronic transport within a coaxially-gated nanowire field-effect transistor (FET) in the Coulomb blockade regime by means of a non-equilibrium Green’s function technique. Two different approaches are considered for the description of the Coulomb interaction: a many-body multi-configurational technique and a mean-field approximation. This allows us to calculate the single-particle density matrix ρ₁ of the nanowire channel for non-equilibrium conditions. In turn, we derive the single-particle-reduced entropy S₁=−Tr(ρ₁ log₂ ρ₁) of the system as a function of the applied bias and gate voltages. S₁ can be interpreted as a measure of deviation from a single Slater-determinant. Within the multi-configurational approach, the numerically obtained entropy diagrams exhibit diamond-shaped structures, resembling the Coulomb diamonds present in the current-voltage characteristics in this transport regime. Finally, we compare the results with those which are obtained within the mean-field approximation.