Conductance

About: Conductance is a research topic. Over the lifetime, 8088 publications have been published within this topic receiving 235961 citations.

A mechanism for conductance switching in carbon-based molecular electronic junctions

Abstract: A molecular junction formed by a 10-15 A organic monolayer between carbon and mercury contacts exhibited conductance switching for several monolayer structures. When the carbon potential was scanned to a sufficiently negative voltage relative to the mercury, the junction resistance suddenly decreased by at least an order of magnitude, and high resistance could be restored by a positive voltage scan. The high and low conductance states were persistent, and conductance switching was repeatable at least 100 cycles for the case of a terphenyl junction. The switching behavior is consistent with phenyl ring rotation and formation of a planar, quinoid structure as a consequence of electron injection into the monolayer. A unique feature of the junction structure is the strong electronic coupling between the monolayer p system and the graphitic carbon through a quinoid double bond. Not only does this interaction lead to high conductivity and possible practical applications as a molecular switch, it also combines the electronic properties of the conjugated monolayer with those of the graphitic substrate. The switching mechanism reported here is an example of ‘‘dry electrochemistry’’ in which a redox process appears to occur under the influence of a high electric field in the absence of solvent or electrolyte. © 2002 The Electrochemical Society. @DOI: 10.1149/1.1490716#

Cole electrical impedance Model-a critique and an alternative

Abstract: The Cole single-dispersion impedance model is based upon a constant phase element (CPE), a conductance parameter as a dependent parameter and a characteristic time constant as an independent parameter. Usually however, the time constant of tissue or cell suspensions is conductance dependent, and so the Cole model is incompatible with general relaxation theory and not a model of first choice. An alternative model with conductance as a free parameter influencing the characteristic time constant of the biomaterial has been analyzed. With this free-conductance model it is possible to separately follow CPE and conductive processes, and the nominal time constant no longer corresponds to the apex of the circular arc in the complex plane.

A nonequilibrium Green's function study of thermoelectric properties in single-walled carbon nanotubes

Abstract: The phonon and electron transport in single-walled carbon nanotubes (SWCNT) are investigated using the nonequilibrium Green's function approach. In zigzag SWCNT ($n$, 0) with $mod(n,3) ot=0$, the thermal conductance is mainly attributed to the phonon transport, while the electron only has few percentage contribution. The maximum value of the figure of merit ($ZT$) is about 0.2 in this type of SWCNT. The $ZT$ is considerably larger in narrower SWCNT because of enhanced Seebeck coefficient. $ZT$ is smaller in the armchair SWCNT, where Seebeck coefficient is small due to zero band gap. It is found that the cluster isotopic doping can reduce the phonon thermal conductance obviously and enhance the value of $ZT$. The uniaxial elongation and compress strain depresses phonons in whole frequency region, leading to the reduction of the phonon thermal conductance in whole temperature range. Interestingly, the elongation strain can affect the phonon transport more seriously than the compress strain, because the high frequency $G$ mode is completely filtered out under elongation strain $\epsilon >0.05$. The strain also has important effect on the subband edges of the electron band structure by smoothing the steps in the electron transmission function. The $ZT$ is decreased by strain as the reduction in the electronic conductance overcomes the reduction in the thermal conductance.