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Abstract: Quantum transport properties through some multilevel quantum dots sandwichedbetween two metallic contacts are investigated by the use of Green-s functiontechnique. Here we do parametric calculations, based on the tight-bindingmodel, to study the transport properties through such bridge systems. Theelectron transport properties are significantly influenced by a number ofquantized energy levels in the dots, b dot-to-electrode coupling strength,c location of the equilibrium Fermi energy $E F$ and d surface disorder. Inthe limit of weak-coupling, the conductance $g$ shows sharp resonant peaksassociated with the quantized energy levels in the dots, while, they getsubstantial broadening in the strong-coupling limit. The behavior of theelectron transfer through these systems becomes much more clearly visible fromour study of current-voltage $I$-$V$ characteristics. In this context we alsodescribe the noise power of current fluctuations $S$ and determine the Fanofactor $F$ which provides an important information about the electroncorrelation among the charge carriers. Finally, we explore a novel transportphenomenon by studying the surface disorder effect in which the currentamplitude increases with the increase of the surface disorder strength in thestrong disorder regime, while, the amplitude decreases in the limit of weakdisorder. Such an anomalous behavior is completely opposite to that of bulkdisordered system where the current amplitude always decreases with thedisorder strength. It is also observed that the current amplitude stronglydepends on the system size which reveals the finite quantum size effect.

Author: Santanu K. Maiti

Source: https://arxiv.org/

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