Silicon-based Molecular Electronics

Rakshit, Titash; Liang, Gengchiau; Ghosh, Arnab; Datta, Supriyo

doi:10.1021/nl049436t

Cited by 203 publications

(206 citation statements)

References 34 publications

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“…(Here, and in what follows we illustrate the theoretical results choosing the parameters at which the calculated currents are in the lA range. Despite this seems high values for a single molecule, nevertheless, such currents are observed for small organic molecules [8,48,54,55].) Fig.…”

Section: Resultsmentioning

confidence: 91%

Kinetic control of the current through a single molecule

et al. 2006

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A unified description is put forward for the electron transmission through a molecule that is attached to two leads with the molecule being characterized by a single level to be populated by the transferred electrons. In deriving the expression for the current the Coulomb interaction is accounted for between the two extra electrons that may occupy the molecular level. The formation of two distinct transmission channels associated with the neutral and the singly charged molecule can directly be related to this interaction. Moreover, each transmission channel comprises a sequential as well as a direct (tunneling) pathway. The first pathway is realized via hopping transitions between the molecule and the neighboring electrodes. Just this inelastic kinetic process is responsible for the kinetic charging of the molecule. Then, the second pathway takes place against the background of kinetic molecular charging. In particular, it is demonstrated that hopping transmissions which are asymmetric with respect to the two electrodes cause a kinetic current rectification. The transient population of the molecule, realized by the transferred electrons, determines the rectification; the latter becomes rather large for resonant transmission.

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Section: Resultsmentioning

confidence: 91%

Kinetic control of the current through a single molecule

et al. 2006

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“…NDR for styrene and saturated cyclic molecules on Si was reported [26,146,147] and explained with a model, [148] which shows that NDR is expected if the molecular level moves in and out of alignment with the semiconductor energy bands. Such scenario requires that the molecular level be located near the semiconductor forbidden gap, a requirement that is certainly not met by alkanes.…”

Section: Negative Differential Resistance (Ndr)mentioning

confidence: 97%

Molecules on Si: Electronics with Chemistry

et al. 2009

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Basic scientific interest in using a semiconducting electrode in molecule‐based electronics arises from the rich electrostatic landscape presented by semiconductor interfaces. Technological interest rests on the promise that combining existing semiconductor (primarily Si) electronics with (mostly organic) molecules will result in a whole that is larger than the sum of its parts. Such a hybrid approach appears presently particularly relevant for sensors and photovoltaics. Semiconductors, especially Si, present an important experimental test‐bed for assessing electronic transport behavior of molecules, because they allow varying the critical interface energetics without, to a first approximation, altering the interfacial chemistry. To investigate semiconductor‐molecule electronics we need reproducible, high‐yield preparations of samples that allow reliable and reproducible data collection. Only in that way can we explore how the molecule/electrode interfaces affect or even dictate charge transport, which may then provide a basis for models with predictive power.To consider these issues and questions we will, in this Progress Report, review junctions based on direct bonding of molecules to oxide‐free Si. describe the possible charge transport mechanisms across such interfaces and evaluate in how far they can be quantified. investigate to what extent imperfections in the monolayer are important for transport across the monolayer. revisit the concept of energy levels in such hybrid systems.

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“…It results from an ability to explicitly separate the mechanical and electronic contributions to the current, which will always be possible for molecules with large HOMO-LUMO gaps and semiconductors where the location of the Fermi energy can be controlled by doping. 13 When combined with the subpicometer control of cryogenic STM, this approach provides snapshots of the dynamics along the reaction coordinate. For molecular electronics, this facilitates a systematic approach to evaluate, in combination with different contacting metals, the performance of candidate molecules in different environments and bonding configurations, and represent an important first step toward the rational design of molecular devices and their operation.…”

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confidence: 99%

Contact Formation Dynamics: Mapping Chemical Bond Formation between a Molecule and a Metallic Probe

et al. 2006

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We present a study that maps out chemical bond formation between a Pt-inked probe and a single 1,3-cyclohexadiene (1,3-CHD) molecule on Si(100). By separating the mechanical and electronic contributions to the current during the approach to contact, we show that there are significant forces between the probe and the CdC of the molecule and we track the relaxation of the molecule, the emergence of a chemical bond feature in the LDOS, and the quenching of specific molecular vibrations during bond formation.Understanding the detailed dynamics of chemical bond formation at surfaces is essential to a wide range of technologies. For example, the prospects for future molecular electronic devices 1-13 hinge on the ability to form reproducible electrical contacts with single molecules. 2,3,14 Little is known about how individual molecules relax or how potentially important device properties such as the HOMO-LUMO gap are modified by the contacting process. Similarly, the operation of catalysts and enzymes depends on understanding how particular molecules react with surface catalytic sites. [15][16][17] The manner in which molecules engage with and ultimately dock at these surface sites is critically important. In these and related systems, numerous studies have reported on the final state properties, that is, after the contact has been assembled or the reaction completed. The actual dynamics of chemical bond formation is poorly understood and represents a serious impediment to the rational design of the materials and devices that underpin these technologies.Here we present a study that maps out chemical bond formation as a Pt-inked probe approaches and makes contact with a single 1,3-cyclohexadiene (1,3-CHD) molecule on Si-(100). By explicitly separating the mechanical and electronic contributions to the current during the approach, we show that there are significant forces 18 between the probe and Cd C region of the molecule and we track both the relaxation and rehybridization of the molecule, the emergence of a chemical bonding feature in the LDOS, and the quenching of specific molecular vibrations, all in excellent agreement with density functional theory (DFT) calculations. We envision that these methods will be useful for identifying candidate metal-molecule systems for device applications and for addressing the operation and selectivity of certain catalysts.Contact and bond formation was studied using a cryogenic STM (Createc) in which a single-crystal Pt(111) metal sample and a Si(100) substrate [n+-type As, <5 mΩ‚cm] were placed in a sample holder that allows each to be heated and prepared separately. Following characterization by LEED, both samples were simultaneously exposed at room temperature to less than 0.1% of a monolayer of 1,3-CHD, transferred into the STM, and cooled to 5 K. Tungsten STM probes were cleaned by electron bombardment and then "inked" with atoms from the Pt substrate using a method described previously 18 and which provided control over the composition of the probe. The Pt-inked prob...

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Silicon-based Molecular Electronics

Cited by 203 publications

References 34 publications

Kinetic control of the current through a single molecule

Kinetic control of the current through a single molecule

Molecules on Si: Electronics with Chemistry

Contact Formation Dynamics: Mapping Chemical Bond Formation between a Molecule and a Metallic Probe

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