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Critical roles of metal-molecule contacts in electron transport through molecular-wire junctions

A. Grigoriev ; Jonas Sköldberg (Institutionen för mikroteknologi och nanovetenskap, Tillämpad kvantfysik) ; Göran Wendin (Institutionen för mikroteknologi och nanovetenskap, Bionanosystem) ; Z. Crljen
Physical Review B Vol. 74 (2006), 4, p. 045401.
[Artikel, refereegranskad vetenskaplig]

We study the variation of electron transmission through Au-S-benzene-S-Au junctions and related systems as a function of the structure of the Au:S contacts. For junctions with semi-infinite flat Au(111) electrodes, the highly coordinated in-hollow and bridge positions are connected with broad transmission peaks around the Fermi level, due to a broad range of transmission angles from transverse motion, resulting in high conductivity and weak dependence on geometrical variations. In contrast, for (unstable) S adsorption on-top of an Au atom, or in the hollow of a 3-Au-atom island, the transmission peaks narrow up due to suppression of large transmission angles. Such more one-dimensional situations may describe more common types of contacts and junctions, resulting in large variations in conductivity and sensitivity to bonding sites, tilting, and gating. In particular, if S is adsorbed in an Au vacancy, sharp spectral features appear near the Fermi level due to essential changes of the level structure and hybridization in the contacts, admitting order-of-magnitude variations of the conductivity. Possibly such a system, can it be fabricated, will show extremely strong nonlinear effects and might work as uni- or bi-directional voltage-controlled two-terminal switches and nonlinear mixing elements. Finally, density-functional theory based transport calculations seem relevant, being capable of describing a wide range of transmission peak structures and conductivities. Prediction and interpretation of experimental results probably require more precise modeling of realistic experimental situations.

Nyckelord: Molecular electronics, transport, metal-molecule-metal junction



Denna post skapades 2007-01-18.
CPL Pubid: 25842

 

Institutioner (Chalmers)

Institutionen för mikroteknologi och nanovetenskap, Tillämpad kvantfysik
Institutionen för mikroteknologi och nanovetenskap, Bionanosystem (2007-2015)

Ämnesområden

Molekylfysik
Mesoskopisk fysik
Kvantkemi

Chalmers infrastruktur

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Denna publikation ingår i:


Molecular Electronics - Modeling, Devices and Architecture