THE EFFECT OF METAL-MOLECULE NANO-CONTACTS WITH DIFFERENT END GROUPS IN MOLECULAR ELECTRONICS

2009 ◽  
Vol 23 (30) ◽  
pp. 5657-5669 ◽  
Author(s):  
SEIFOLLAH JALILI ◽  
ABDOLHAKIM PANGH
Keyword(s):  
Electron Transport ◽  
Molecular Electronics ◽  
Atomic System ◽  
Transmission Function ◽  
Molecular Wires ◽  
Atomic Systems ◽  
Current Voltage ◽  
Electron Transport Properties ◽  
Current Voltage Characteristics ◽  
Function Density

We investigated the electron transport properties of thiophen-bithiol-based molecular wires through atomic metal–thiophen–metal systems using the first principle methods. Various metal–thiophen–metal atomic systems are constructed with different end atoms (S, Se, and Te). The electron transport of the atomic system is systematically studied by analysis of transmission function, density of states, and current–voltage characteristics of the systems.

Ab Initio Study of the Sub-threshold Electron Transport Properties of Ultra-scaled Amorphous Phase Change Material Germanium Telluride

2014 ◽  
Vol 1697 ◽  
Author(s):  
Jie Liu ◽  
Xu Xu ◽  
M. P. Anantram
Keyword(s):  
Electron Transport ◽  
Ab Initio ◽  
Transport Properties ◽  
Defect States ◽  
Germanium Telluride ◽  
Voltage Curve ◽  
Current Voltage ◽  
Current Voltage Curve ◽  
Electron Transport Properties ◽  
Change Material

ABSTRACTThe sub-threshold electron transport properties of amorphous (a-) germanium telluride (GeTe) phase change material (PCM) ultra-thin films are investigated by using ab initio molecular dynamics, density function theory, and Green’s function simulations. The simulation results reproduce the trends in measured electron transport properties, e.g. current-voltage curve, intra-bandgap donor-like and acceptor-like defect states, and p-type conductivity. The underlying physical mechanism of electron transport in ultra-scaled a-PCM is unraveled. We find that, though the current-voltage curve of the ultra-scaled a-PCM resembles that of the bulk a-PCM, their physical origins are different. Unlike the electron transport in bulk a-PCM, which is governed by the Poole-Frenkel effect, the electron transport in ultra-scaled a-PCM is largely dominated by tunneling transport via intra-bandgap donor-like and acceptor-like defect states.

Irregular Electron Transport Through a-Si:H Based Potential Barriers

1993 ◽  
Vol 297 ◽  
Author(s):  
Norbert Bernhard ◽  
B. Frank ◽  
B. Movaghar ◽  
G.H. Bauer
Keyword(s):  
Electron Transport ◽  
Transport Mechanism ◽  
Current Transport ◽  
Transport Mechanisms ◽  
Potential Barriers ◽  
Resonant Tunnelling ◽  
Current Voltage ◽  
Different Temperatures ◽  
Current Voltage Characteristics ◽  
Stable Formation

Irregularities in the current-voltage-characteristics of a-Si:H based potential barriers have been investigated experimentally, and are discussed theoretically with respect to different transport mechanisms. The investigated samples were different series of double and single barrier a-Si:H - a-Si1-xCx:H - heterostructures, as well as homogeneous samples without heterostructure barrier. Current-voltage-(I-V)-characteristics showing a wide variety of features, from complete smoothness of the curves, to bumps and even accidental step-like switching behaviour, as well as different forms of noise, were recorded at different temperatures. Resonant tunnelling as an explaining transport mechanism for the anomalies was excluded because of inconsistency between experiment and calculations partially including special amorphous features. Instead it is argued that all observed irregularities, i. e. bumps in I-V-curves, switching-like behaviour, and appearance of noise, are related to current transport via trap-assisted tunnelling through locally strongly confined transport paths, leading to the meta-stable formation, change and break-down of conductory filaments.

scholarly journals Electron transport in AlGaN/GaN HEMT-like nanowires: Effect of depletion and UV excitation

2021 ◽  
Vol 24 (04) ◽  
pp. 407-412
Author(s):  
A.V. Naumov ◽  
◽  
V.V. Kaliuzhnyi ◽  
S.A. Vitusevich ◽  
H. Hardtdegen ◽  
...  
Keyword(s):  
Electron Transport ◽  
Space Charge ◽  
Ultraviolet Excitation ◽  
Gan Hemt ◽  
Current Voltage ◽  
Significant Difference ◽  
Current Voltage Characteristics ◽  
Uv Excitation ◽  
Biosensor Applications ◽  
Space Charge Limited

In this work, we have investigated the features of electron transport in AlGaN/GaN transistor-like heterostructures with nanowires of different width. These nanostructures are studied extensively because of their great electronic and sensing advantages for electronic biosensor applications. We study the depletion effects and impact of ultraviolet excitation on the electron transport in sets of nanowires of different width from 1110 down to 185 nm. We have found significant difference in electrical characteristic’s behavior between wide (1110…480 nm) and narrow (280…185 nm) nanowires and have observed regions related to space-charge-limited transport for the narrowest nanowires. Also, we obtained evident dependence of nanowire’s current-voltage characteristics on the wavelength and energy of UV excitation. External UV excitation allows us to control the depletion widths in nanowires and effectively tune space-charge-limited transport.

NANOPATTERNED CROSSBAR STRUCTURES FOR MOLECULAR ELECTRONICS

2005 ◽  
Vol 04 (04) ◽  
pp. 461-465
Author(s):  
JIE DENG ◽  
BENG TIAM SAW ◽  
K. H. AARON LAU ◽  
OLIVER WILHELMI ◽  
HERBERT O. MOSER ◽  
...  
Keyword(s):  
Molecular Electronics ◽  
Electron Beam Lithography ◽  
Intermediate Layer ◽  
Pattern Transfer ◽  
Metal Electrodes ◽  
Nanoelectronic Devices ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Crossbar Architecture ◽  
Crossing Point

Nano-patterned crossbar structures were fabricated as test structures for the development of nanoelectronic devices based on functional molecules. The crossbar structures serve as a platform for testing electronic properties of molecules and their interface to metal electrodes. The fabrication of the crossbar structures involved electron-beam lithography of sub-100-nm features aligned to electrodes pre-patterned by UV lithography and the deposition of and pattern transfer into an intermediate layer. The molecules to be tested were self-assembled as a monolayer on the nano-patterned area. The top electrode structures were subsequently deposited on top of the intermediate layer. The crossbar architecture allows measuring the current-voltage characteristics across the molecules for each crossing point individually.

First-Principles Study of Electron Transport Behavior through Porphyrin Molecular Wires

2010 ◽  
Vol 663-665 ◽  
pp. 616-619 ◽  
Author(s):  
Yan Wei Li ◽  
Jin Huan Yao ◽  
Xing Sheng Deng ◽  
Xiao Xi Huang
Keyword(s):  
Electron Transport ◽  
First Principles ◽  
Density Functional ◽  
Molecular Wires ◽  
Quantum Mechanical ◽  
Functional Theory ◽  
Transport Behavior ◽  
Electron Transport Properties ◽  
Ab Inito ◽  
Exponential Relation

The nonequilibrium Green’s function approach in combination with density-functional theory is used to perform ab inito quantum-mechanical calculations of the electron transport properties of porphyrin oligomers sandwiched between two gold electrodes. The results show that porphyrin oligomers are good candidates for long-range conduction wires. In particular, the decay of conductance of porphyrin oligomers does not follow the exponential relation. The electron transport behavior was analyzed from the molecular projected self-consistent Hamiltonian states and the electron transmission spectra of the molecular junctions.

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 Calculation of CO adsorption capacity of single iron(II)- porphyrin and related electron transfer behavior by DFT theory

2020 ◽  
Author(s):  
Placido G. Mineo
Keyword(s):  
Density Functional ◽  
Co Adsorption ◽  
Molecular Wires ◽  
Molecular Wire ◽  
Dft Theory ◽  
Functional Theory ◽  
Current Voltage ◽  
End Groups ◽  
Transfer Behavior ◽  
Current Voltage Characteristics

The effect of CO adsorption on the electron transport behavior of single iron(II)-porphyrin molecular wire with sulfur end groups bonded to two gold electrodes isinvestigated using nonequilibrium Green's function formalism combined with firstprinciples density functional theory. The current-voltage characteristics of the singleFe-porphyrin molecular wires with and without CO adsorption are calculated. Theresults demonstrate that Fe-porphyrin molecular wire shows a negative differentialresistance (NDR) at 2.0 V

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