Conductivity of thin films

Electronic conductivity of thin-film solid electrolytes. Besides having low electronic transference numbers, it is essential for thin films of the order of 1 jim that the magnitude of the electronic resistance is low in order to prevent self-discharge of the battery. For this reason, specific electronic resistances in the range of 1012-1014 Qcm are required for thin-film solid electrolytes. Often the color may be a valuable indication of the electronic conductivity. In this regard, solid electrolytes should preferably be transparent white [20]. 

The effect of humidity on conductivity of thin films of poly(dG)-poly(dC) and poly(dA)-poly(dT) in air was also investigated. It was found that above 20% relative humidity (RH) the conductance increases exponentially with RH [68]. It was concluded that the resistance of the films is not determined by that of the DNA, but rather by conduction through the hydration layers surrounding the DNA molecules in the film [68]. 

Dowden and Reynolds (I) have cited several examples of the parallelism between reaction rates in catalysis and electron density in other adsorbents. Extensive work by Garner and his co-workers (2,3) has shown clearly the intimate relation between adsorption and the conductivity of copper oxide. Clarke (4) and Morrison (5) have shown that adsorption changes the resistance of germanium. In metals, there appears a similar effect, Suhrmann and Schulz (6) have demonstrated the dependence of the conductivity of thin films of nickel on the adsorption of various gases. 

Table 2 contains idealized structures of some CPs with typical dopants and values for the conductivities of thin films. The exact structures of PPy and poly thiophene (PT) are unknown. Polyacetylene is the most crystalline and PANi can exist in several oxidation states with electrical conductivities varying from 10 S/cm to the values reported in Table 2. In its undoped state, PPS is an engineering thermoplastic with a conductivity of less than 10 S/cm. Upon doping with ASF5, conductivities as high as 200S/cm have been obtained after casting a film from a solution of AsFsP ...

Figure 8. Temperature-dependent conductivity of thin film simple oxides and a-Fe203-Sn02 composites in air, RH 30%...

One method used to improve the thermal conductivity of thin film, metallized almnina substrates is to place filled thermal vias under the high-dissipating devices, hi this process, holes are drilled into the alumina, filled with copper-tungsten, fired, and lapped flat [39]. 

While films of PP are highly conducting, the conductivity of thin films of poly( 1-methylpyrrole) is approximately 10 Scm [101]. This is generally attributed to lack of planarity or to increased chain separation in the polymer resulting from steric hindrance and twisting caused by the A/-methyl group. Thus, the conductivity of films of the copolymer depends on the mole ratio of monomer units in the copolymer [5,101-5]. 

A more detailed model for the treatment of steady-state feedback data from which the conductivity of thin films can be extracted was reported in Ref. [65]. It was shown that an accurate determination of K can be achieved by using an approximate method for processing multiple data sets and including a constant calibration factor. 

Fig. 19 Influence of pH and SWCNT loadings on the electrical conductivity of thin films of SWCNT/polyaniline composite nanofibers (Reproduced with permission from [78])...

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