Conductivity doping dependence

Recently, intense interest has been paid on doped poly(acetylene) because its film 68) showed markedly high conductivity on doping69 70 71 and the n- and p-type conductivities are depending on the dopants. The confirmation of p-n junction formation with the p- and n-type -fCH T, has roused great expectations to produce a polymer film solar cell.72a)... 

We have doped sulfur lignin and sodium lignosulfonate in vapor-phase (iodine, bromine, and ammonia) and in liquid phase (sodium and ferrichlo-ride). The conductivity mainly depends on the nature of the dopant ion and the doping degree. Doping can be monitored by IR-spectroscopy. The intensities of the peaks decrease, and the fine structure vanishes, when the... 

The bulk conductivity a depends on the concentration of charge carriers and on their mobility, either of which can be modulated by exposure to the gas. The first prerequisite of such an interaction is the penetration of the analyte to the interior of the layer. The second is the ability of the gas to form a charge-transfer complex with the selective layer. This process then constitutes secondary doping, which affects the overall conductivity. For a mixed semiconductor, the overall conductivity is determined by the combined contribution from the holes (p) and electrons (n), as given by the general conductivity equation. 

The ability of semiconductors to conduct electricity depends greatly transistor was made m the on the presence of small amounts of impurities. The addition of an impurity to a semiconductor is called doping. Doping a semiconductor has significant effects on its ability to conduct an electric current. 

In the case of conjugated conducting polymers, which were previously mentioned, the ET theory applies since the conductivity is not a simple band type conductivity but, depending on the doping level, merely an intrachain and/or interchain motion of charged soliton-like or polaron-like defects. We can sketch this motion as indicated in Fig. 36.26. 

WOj doped with Au and Ru Conductivity Sensitivity depends on thickness and anneahng temp. 

On doping with chromium, nickel oxide that is initially p-type becomes less p-type conducting. Whether this permits making NiO n-type in this way depends on the equilibrium constants. The electronic conductivity also depends on the capture reactions of the charge carriers by the localized stationary defects. 

The conductivity may depend on other factors for instance on the pH of the contacting solution (proton doping in the case of polyaniline) (Fig. 6.7) or on the presence of electron donor molecules in the gas phase. 

It was realized quite early that the parent, undoped, compounds should be viewed as Mott insulators. More recent studies of the doping dependence have revealed the generic features between cuprates and other classes of Mott insulators. The principal trends in the evolution of the in-plane electronic conductivity with doping are in accord with the results of the calculations performed for Mott-Hubbard systems as will be described in sect. 3. 

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