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Fabricating Nanogaps by Nanoskiving
Published on: May 13, 2013
Strong conductance variation in conformationally constrained oligosilane tunnel junctions
Christopher B George1, Mark A Ratner, Joseph B Lambert
1Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA. c-george@northwestern.edu
The Journal of Physical Chemistry. A
|March 14, 2009
Summary
Molecular conformation significantly impacts electrical conductance in silicon-based molecular junctions. Changes in molecular shape alter electron flow by up to 1000x, crucial for nanoelectronic device design.
Area of Science:
- Molecular electronics
- Condensed matter physics
- Computational chemistry
Background:
- Understanding molecular conformation's role in charge transport is key for designing novel electronic components.
- Oligosilane chains offer tunable electronic properties for molecular junctions.
Purpose of the Study:
- To investigate theoretically how molecular conformation affects electrical conductance in oligosilane-bridged metal-molecule-metal junctions.
- To elucidate the relationship between molecular structure, orbital energies, and charge transport.
Main Methods:
- Utilizing density functional theory (DFT) for electronic structure calculations.
- Employing the nonequilibrium Green's function (NEGF) approach to model charge transport.
- Analyzing hexasilane diamine chains with varying dihedral angles.
Main Results:
- Conductance varied by up to three orders of magnitude with changes in SiSiSiSi dihedral angles.
- Conformational dependence is attributed to sigma-delocalization affecting highest occupied molecular orbital (HOMO) energy levels.
- Transport properties showed extreme sensitivity to the alignment between HOMO energies and the gold electrodes' Fermi level.
Conclusions:
- Molecular conformation is a critical factor controlling conductance in oligosilane-based molecular junctions.
- The study highlights the importance of orbital energy alignment for efficient charge transport.
- Findings provide insights for designing molecular wires and switches with tunable electronic properties.
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