First-principles determination of the effects of intermolecular interactions on the electronic transport through molecular monolayers

Agapito, Luis A.; Cao, Chao; Cheng, Hai‐Ping

doi:10.1103/physrevb.78.155421

Cited by 15 publications

(23 citation statements)

References 50 publications

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“…Our result differ from the Ref. 13 in that the LUMO peak in the transmission function of the Au-2cisAB-Au junction slightly shifts to a lower energy which is closer to the Fermi level as compared to the Au-cisAB-Au. Nevertheless, the transmission coefficients for the HOMO resonance peak and for the energy region around the Fermi level are decreased by about one order of magnitude.…”

Section: Effect Of Molecular Packing Densitycontrasting

confidence: 99%

“…However, for the cis configuration, the junction's transmission coefficients are significantly reduced especially in the energy region around the Fermi level. The decrease in conductance by increasing the packing density has also been observed in other monolayer junctions 13 , but the reason has been attributed to a shift of the LUMO resonance peak in the transmission function to a higher energy away from the Fermi level. Our result differ from the Ref.…”

Section: Effect Of Molecular Packing Densitymentioning

confidence: 56%

“…The conductance of a junction with and without chemicontacts can differ by several orders of magnitude 11,12 . In addition, SAMs can form with differences in packing density and tilt angle, and in densely packed SAMs the conductance may involve both intramolecular and intermolecular contribution due to molecules in close proximity 13 . Other effects such as the surface topography and roughness of the contact also influence the final geometry of the contact and thus lead to more complex transport properties.…”

Section: Introductionmentioning

confidence: 99%

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Electronic and transport properties of azobenzene monolayer junctions as molecular switches

Wang

Cheng

2012

Phys. Rev. B

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We investigate from first-principles the change in transport properties of a two-dimensional azobenzene monolayer sandwiched between two Au electrodes that undergoes molecular switching. We focus on transport differences between a chemisorbed and physisorbed top monolayer-electrode contact. The conductance of the monolayer junction with a chemisorbed top contact is higher in trans configuration, in agreement with the previous theoretical predictions of one-dimensional single molecule junctions. However, with a physisorbed top contact, the "ON" state with larger conductance is associated with the cis configuration due to a reduced effective tunneling pathway by switching from trans to cis, which successfully explains recently experimental measurements of azobenzene monolayer junctions. A simple model is developed to explain electron transmission across subsystems in the molecular junction. We also discuss the effects of monolayer packing density, molecule tilt angle, and contact geometry on the calculated transmission functions. In particular, we find that a tip-like contact with chemisorption significantly affects the electric current through the cis monolayer, leading to highly asymmetric current-voltage characteristics as well as large negative differential resistance behavior.

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Section: Effect Of Molecular Packing Densitycontrasting

confidence: 99%

Section: Effect Of Molecular Packing Densitymentioning

confidence: 56%

Section: Introductionmentioning

confidence: 99%

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Electronic and transport properties of azobenzene monolayer junctions as molecular switches

Wang

Cheng

2012

Phys. Rev. B

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“…In Figure 2b we show the projected electronic density of states (PDOS) of the infinite junction on G (red) and on C (blue) [52]. The eigenenergies of the junction "projected" on the C-G base pair are shown with vertical lines.…”

Section: B Gnr-base-pair-gnr Junctionsmentioning

confidence: 99%

Aviram–Ratner rectifying mechanism for DNA base-pair sequencing through graphene nanogaps

Agapito¹,

Gayles²,

Wolowiec³

et al. 2012

Nanotechnology

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We demonstrate that biological molecules such as Watson-Crick DNA base pairs can behave as biological Aviram-Ratner electrical rectifiers because of the spatial separation and weak hydrogen bonding between the nucleobases. We have performed a parallel computational implementation of the ab-initio non-equilibrium Green’s function (NEGF) theory to determine the electrical response of graphene—base-pair—graphene junctions. The results show an asymmetric (rectifying) current-voltage response for the Cytosine-Guanine base pair adsorbed on a graphene nanogap. In sharp contrast we find a symmetric response for the Thymine-Adenine case. We propose applying the asymmetry of the current-voltage response as a sensing criterion to the technological challenge of rapid DNA sequencing via graphene nanogaps.

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“…The electronic transport through the graphene FET is calculated employing the combined density functional theory (DFT) and Green's function approach 41,42, in which the finite device scattering region M , shown in Figure 1c, is made infinite by mathematically attaching semi-infinite left and right (5,7)-reconstructed leads. The spin-dependent current, I σ , in the graphene junctions is determined as a function of both the applied bias voltage V bias and “ gate ” field F , from…”

Section: Magnetic Graphene Fetmentioning

confidence: 99%

“Seamless” Graphene Interconnects for the Prospect of All-Carbon Spin-Polarized Field-Effect Transistors

Agapito

Kioussis

2011

J. Phys. Chem. C

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Magnetism in graphene nanofragments arises from the spin polarization of the edge-states; consequently, as the material inexorably shrinks, magnetism will become a dominant feature whereas the bulk carrier mobility will be less relevant. We have carried out an ab initio study of the role of graphene-ultra-nanofragment magnetism on electronic transport. We present, as a proof-of-concept, a nanoscopic spin-polarized field-effect transistor (FET) with the channel and metallic contacts carved from a single graphene sheet. We demonstrate the selective tuning of conductance through electric-field control of the magnetic, rather than the charge, degrees of freedom of the channel, the latter typically employed in microscopic graphene FETs. KeywordsSpintronics; FET; graphene diamond; graphene ribbon Similar to carbon nanotubes, graphene holds great promise for future electronics because of its outstanding electrical 1,2 , mechanical 3 , and thermal 4 properties. Because of its 2-dimensionality, however, graphene has the additional advantage for large-scale integration devices fabricated via solid-state lithographic techniques. The fabrication of all-carbon fieldeffect transistors (FETs), where the metallic leads, central dot, and gates are carved from a single sheet of graphite, is currently the subject of intense research 5,6 7 .Graphene displays exceptional high carrier mobility 1,2 allowing for microscopic graphene FETs that are faster than their silicon counterparts 8 . On the other hand, as electronics taps into nano-scale graphene ribbons or fragments (< 50 nm), the edge states become dominant. These states are robust for any random-shaped graphene nanofragments as long as the underlying honeycomb lattice is not substantially modified 9 . The edge-states of graphene ultra-nanofragments have been predicted to be magnetic 10,11 , where the various magnetic states lead to distinct electrical properties 12 . This magnetic ordering may be the underlying origin of the experimentally observed conductance switching 7,13 and band gap modulation 14,15 in graphene nanofragments.Following the silicon-electronics breakthrough microchip paradigm of (1) fabricating all necessary discrete electrical components and wiring from silicon and (2) integrating all these elements in the same silicon wafer, very-large-scale integration in all-carbon graphene devices will require (i) a robust building block analog to the silicon transistor, and (ii) seamless coupling of these nano-units through graphene nanoribbon interconnects, which will allow in turn for ballistic transport. Isolated diamond-shaped graphene flakes, * To whom correspondence should be addressed: luis.agapito@gmail.com. The effect of edge-states of graphene nanofragments on the transport properties in all-carbon spintronics is of central interest and importance and it has not been addressed theoretically thus far. In this article we use ab initio electronic structure and Landauer-Büttiker transport calculations to demonstrate, as a proof-of-concept, that diamond gra...

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First-principles determination of the effects of intermolecular interactions on the electronic transport through molecular monolayers

Cited by 15 publications

References 50 publications

Electronic and transport properties of azobenzene monolayer junctions as molecular switches

Electronic and transport properties of azobenzene monolayer junctions as molecular switches

Aviram–Ratner rectifying mechanism for DNA base-pair sequencing through graphene nanogaps

“Seamless” Graphene Interconnects for the Prospect of All-Carbon Spin-Polarized Field-Effect Transistors

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