Devices molecular junction

Second, in designing new molecule-based electronic devices, one of the major goals is the precise control of the current flowing between the terminals. Electrochemical molecular junctions allow for control of the potentials of the electrodes with respect to the redox potential of incorporated redox-active molecules with well-defined, accessible, tunable energy states. These junctions represent unique systems able to predict precisely at which applied potential the current flow will take off. Even though the presence of a liquid electrolyte represents a detriment towards possible applications, they provide the concepts for designing molecular devices that mimic electronic functions and control electrical responses. 

Blackstock JJ, Stickle WF, Donley CL, Stewart DR, Williams RS (2007) Internal structure of a molecular junction device chemical reduction of Pt02 by Ti evaporation onto an interceding organic monolayer. J Phys Chem C 111 16-20... 

FIGURE 3.6. (a) Cross-sectional schematics of a silicon wafer with a nanopore etched through a suspended silicon nitride membrance. SAM is formed between sandwiched Au eletrodes in the pore area (circled), (b) I(V) characteristics of a Au-2 -amino-4-ethynylphenyl-4-ethynylphenyl-5 -nitro-1 -benzenethiolate-Au (chemical structure shown below) molecular junction device at 60 K. The peak current density is 50 A/cm2, the NDR is 2400 pQ. cm2, the peak-to-valley ratio is 1030 1. [Adapted from Ref.30 Chen el al., Science 286, 1550-1552 (1999).]... 

Current fabrication schemes for solid-state three-terminal molecular junctions typically rely on electromigration [78] to produce a nanoscale gap between two metallic electrodes which rests on top of a gate electrode, separated by a thin oxide layer. A schematic representation of a three-terminal device is shown in Fig. 10.15. 

Molecular-based electronic devices used as active components in nanoelectronics were r eeently p roposed [ 1 ]. The b asic function o f su ch d evices i s a t wo-terminal molecular junction that can be electrically switched between high- and low-conductance states. Rational design of the switching molecule can be employed to optimize the switching characteristics because they are mainly dependent on the properties of the molecule. 

We have presented here several theoretical tools for exploring mechanisms of heat flow in molecular junctions a generalized Langevin equation approach, the master equation formalism, and classical MD simulations. Using these techniques, we have inferred that the thermal conductance of nanosystems results from an intricate interplay between the molecular structure, the contact properties, and the reservoir s spectral functions. Our minimal single-mode junction model clearly exposed the role of anharmonic interactions in bringing out nonlinear transport characteristics. This has lead us to propose unique thermal devices, a thermal rectifier and a heat pump. 

The construction of externally switched solid-state devices awaits development of molecular junctions sandwiched between two electrodes [89]. They may, for example, consist of CyD-based meccano molecules such as rotaxanes (discussed in Chapter 12) for which switching in the solution phase or in monolayers has been demonstrated [21]. 

In order to reduce the size of integrated circuits, the technologies used to fabricate them have been continuously changing. As circuit features approach the nanometer scale, it has been proposed that devices (diodes, transistors, resistors, capacitors, and conductive tracks) could be made from molecules with suitable properties, instead of patterned doped silicon layers [65]. For that purpose, it is essential to characterize their electronic properties at the level of single molecules, and the molecular junction methods described above offer many advantages to do it. 

Among these one of the most promising concepts is the development of single electron (SE) devices, which retain their scalability down to the molecular level. At present, due to exploitation of charging (Coulomb) effects in metallic SE devices comprising tunnel junctions with submicrometer size, individual charge carriers can be handled... 

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