STRANGE EFFECT OF DISORDER ON ELECTRON TRANSPORT THROUGH A THIN FILM

2008 ◽  
Vol 07 (02n03) ◽  
pp. 171-178
Author(s):  
SANTANU K. MAITI
Keyword(s):  
Thin Film ◽  
Electron Transport ◽  
Disordered Systems ◽  
Tight Binding ◽  
Finite Size ◽  
Anomalous Behavior ◽  
Disorder Strength ◽  
Weak Disorder ◽  
Binding Model ◽  
Strong Disorder

A novel feature of electron transport is explored through a thin film of varying impurity density with the distance from its surface. The film, attached to two metallic electrodes, is described by simple tight-binding model and its coupling to the electrodes is treated through Newns–Anderson chemisorption theory. It is observed that in the strong disorder regime the amplitude of the current passing through the film increases with the increase of the disorder strength, while it decreases in the weak disorder regime. This anomalous behavior is completely opposite to that of conventional disordered systems. Our results also predict that the electron transport is significantly influenced by the finite size of the thin film.

scholarly journals ELECTRON TRANSPORT THROUGH MULTILEVEL QUANTUM DOT

2008 ◽  
Vol 07 (01) ◽  
pp. 51-61 ◽  
Author(s):  
SANTANU K. MAITI
Keyword(s):  
Electron Transport ◽  
Transport Properties ◽  
Energy Levels ◽  
Tight Binding ◽  
Current Amplitude ◽  
Function Technique ◽  
Noise Power ◽  
Disorder Strength ◽  
Binding Model ◽  
Surface Disorder

Quantum transport properties through some multilevel quantum dots sandwiched between two metallic contacts are investigated by the use of Green's function technique. Here, we do parametric calculations, based on the tight-binding model, to study the transport properties through such bridge systems. The electron transport properties are significantly influenced by (a) the number of quantized energy levels in the dots, (b) the dot-to-electrodes coupling strength, (c) the location of the equilibrium Fermi energy E F , and (d) the surface disorder. In the limit of weak-coupling, the conductance (g) shows sharp resonance peaks associated with the quantized energy levels in the dots, while, they get substantial broadening in the strong-coupling limit. The behavior of the electron transfer through these systems becomes much more clearly visible from our study of the current–voltage (I–V) characteristics. In this context, we also describe the noise power of current fluctuations (S) and determine the Fano factor (F) which provides an important information about the electron correlation among the charge carriers. Finally, we explore a novel transport phenomenon by studying the surface disorder effect in which the current amplitude increases with the increase of the surface disorder strength in the strong disorder regime, while, the amplitude decreases in the limit of weak disorder. Such an anomalous behavior is completely opposite to that of bulk disordered system where the current amplitude always decreases with the disorder strength. It is also observed that the current amplitude strongly depends on the system size which reveals the finite quantum size effect.

scholarly journals QUANTUM TRANSPORT THROUGH HETEROCYCLIC MOLECULES

2009 ◽  
Vol 23 (02) ◽  
pp. 177-187
Author(s):  
SANTANU K. MAITI ◽  
S. N. KARMAKAR
Keyword(s):  
Electron Transport ◽  
Transport Properties ◽  
Energy Levels ◽  
Tight Binding ◽  
Molecular Transport ◽  
Molecular Wires ◽  
Function Technique ◽  
Binding Model ◽  
Heterocyclic Molecules ◽  
Electron Transport Properties

We explore electron transport properties in molecular wires made of heterocyclic molecules (pyrrole, furan and thiophene) by using the Green's function technique. Parametric calculations are given based on the tight-binding model to describe the electron transport in these wires. It is observed that the transport properties are significantly influenced by (a) the heteroatoms in the heterocyclic molecules and (b) the molecule-to-electrodes coupling strength. Conductance (g) shows sharp resonance peaks associated with the molecular energy levels in the limit of weak molecular coupling, while they get broadened in the strong molecular coupling limit. These resonances get shifted with the change of the heteroatoms in these heterocyclic molecules. All the essential features of the electron transfer through these molecular wires become much more clearly visible from the study of our current-voltage (I-V) characteristics, and they provide several key information in the study of molecular transport.

scholarly journals Probing the Global Delocalization Transition in the de Moura-Lyra Model with the Kernel Polynomial Method

2020 ◽  
Vol 233 ◽  
pp. 05011
Author(s):  
N.A. Khan ◽  
J.P. Santos Pires ◽  
J.M. Viana Parente Lopes ◽  
J.M.B. Lopes dos Santos
Keyword(s):  
Nearest Neighbor ◽  
Tight Binding ◽  
Localization Length ◽  
Polynomial Method ◽  
Tight Binding Model ◽  
Weak Disorder ◽  
Binding Model ◽  
One Dimensional ◽  
Open Boundaries ◽  
Kernel Polynomial Method

In this paper, we report numerical calculations of the localization length in a non-interacting one-dimensional tight-binding model at zero tem¬perature, holding a correlated disorder model with an algebraic power-spectrum (de Moura-Lyra model). Our calculations were based on a Kernel Polynomial implementation of the Thouless formula for the inverse localization length of a general nearest-neighbor 1D tight-binding model with open boundaries. Our results confirm the delocalization of all eigenstates in de Moura-Lyra model for α > 1 and a localization length which diverges as ξ ∝ (1 – α)–1 for α → 1–, at all energies in the weak disorder limit (as previously seen in [12]).

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