Negative differential resistance NDR

Among the two-terminal devices that can be imagined for UE [capacitors, inductors, rectifiers, negative differential resistance (NDR) devices], the simplest is a molecular wire, that is, a molecule capable of conducting electricity a nanoconductor or, equivalently, a nanoresistor. Even the most conductive of molecular wires has a minimum resistance. 

In addition and importantly, even in non-active junctions, when the electrode Fermi level matches the molecular bridge energy levels, resonance phenomena can generate electrical behaviours similar to those of conventional electronic devices, such as rectification [86-89] and negative differential resistance (NDR) [90, 91]. 

In 1999 large ON-OFF ratios and negative differential resistance (NDR) were measured in molecular electronic devices constructed using functionalized OPEs and a nanopore test... 

In a study employing negative differential resistance (NDR) features of H3PM012O40 HPA substituted with V, Barteau and coworkers have shown there is a relationship between their values and the redox potentials of the samples, and... 

Mark Reed and coworkers found that abont 5000 molecnles of 2 -amino-4-ethynylphenyl-4 -ethynylphenyl-5 -nitro-benzene-l-thiolate in a nanopore, attached to Au on one side and topped by a Ti electrode on the other, provided not only rectification (because of the dissimilar metal electrodes) but also negative differential resistance (NDR). ° However, the NDR devices were unreliable and efforts to commercialize them failed. 

The picture completely changes if we reach a current-controlled negative-differential-resistance (NDR) regime. As a consequence of NDR the current distribution decays into filaments. In the simplest model two parameters are needed. One is the breakdown field, or threshold field, for growth of a filament F, and the other is the channel field Pch (Zeller, 1987 Wiesmann and Zeller, 1986). The contraction into filaments leads to the situatibn that a local field enhancement becomes self-enhanced and propagating at the tip of the filament. If V > then the filament will reach the counter-electrode and breakdown will occur. 

Compound 34 was synthesized according to Scheme 3.62 using the previously described 33. Compound 34 is analogous to a thiol-terminated nitroaniline that previously exhibited negative differential resistance (NDR) in a device embodiment. ... 

Comparing Fig. 30 with Fig. 4, we can assume that in the potential region between 1.0 and 1.3 V, methanol oxidation could be an example for a negative differential resistance (NDR) system. In addition, from Fig. 30, it can be concluded that A-shaped systems with a negative differential resistance can oscillate at constant potential [current oscillations), but not at constant current. As we see below under Sect. 5.2.5.3 and Fig. 35, indeed, current oscillations are to be observed. The surface properties are modified by an electrochemical reaction alone, by the formation of platinum oxide. This Pt-0 formation is followed by a chemical reaction between the oxide and methanol in solution. CO2 is produced, and the current at the free surface sites increases to form new surface oxide, until the surface coverage approaches its maximum and the chemical reaction becomes stronger again. And the cycle starts anew. A characteristic of the (simple) NDR oscillators is that only one potential-dependent process is involved, that is, the electrochemical oxide formation. 

Negative differential resistance (NDR) is used to describe electrical behavior where the current decreases with an increasing applied voltage. A well-known application of NDR is the Esaki or... 

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