And the field effect

At this point, the symmetry of the situation shown in Figure 11.7 becomes helpful. We realize that [/ goes through a minimum at the midpoint position that is, d J//dx = 0 at x = h/2. Thus the constant in Equation (75) equals the pressure at the midpoint ph/2. The difference between the pressure and the field effect is equal to this quantity at all locations between the plates. Because of this constancy, the entire inner region is characterized by the parameters that apply at the midpoint. Therefore ph/2 is the potential that governs the repulsion between... 

Inductive effect — is an effect of the transmission of charge through a chain of atoms by electrostatic induction on rates of reaction, etc. A theoretical distinction may be made between the field effect, and the inductive effect as models for the Coulomb interaction between a given site within a -> molecular entity and a remote unipole or - dipole within the same entity. The experimental distinction between the two effects has proved difficult, except for molecules of peculiar geometry, which may exhibit reversed field effects . Typically, the inductive effect and the field effect are influenced in the same direction by structural changes in the molecule and the distinction between them is not clear. Therefore, the field effect is often included in the term inductive effect . Thus, the separation of a values (see -> electronic effect) into inductive and resonance components does... 

The thermal emission experiments, therefore, do not give a completely clear picture of the gap state distribution because of the conflicting results. A remaining question is whether the differences between the DLTS results in the doped samples and the field effect and SCLC data on undoped a-Si H are due to an effect of doping on the shape of the density of states, or whether they are due to experimental artifacts. 

Typical DHa6T OTFT I-V characteristics are reported in figure 3. The curves are relevant to OTFT of different channel length, namely 1 and 0.2 mm. The square root of I vs. Vg curves are reported as inset of the figures as well (figures 3a and 3b insets). The devices were tested as p-channel materials and the field effect mobilities in saturation regimes were extracted using the well-know equation [10] ... 

The difficulty of such measurements is also seen in the investigations by Servet e/ al. [46] which correlate their X-ray data on differently prepared a6T films (compare Section 3.4) with conductivity data. Although the structural order increases with increasing substrate temperature a decrease in the absolute value is obtained from 6xlO S/cm for 7 s b = 77K to 1.2xl0 S/cm for Tsub = 553 K (conductivity measured parallel to the substrate surface) which is attributed to the desorption of impurities from the substrate which can act as dopants. The anisotropy, however, is increased as expected and the field effect mobility remains nearly constant. 

It should be stressed that the adsorption of isotherms accompanied by charge transfer differ from those measured in the absence of the latter even on uniform surfaces. In Refs. [70-74], the isotherm of adsorption with charge transfer are considered, and the field effect is introduced by two different ways via the Nemst Equation and by considering the displacement of water molecules whose adsorption changes with potential. This is why the author refers to this as combined isotherm. 

Cobalt-PPy-cobalt nanowire was electrochemically synthesized inside alumina membrane and the field-effect transistors were fabricated by patterning a gate on one side of the cobalt-PPy-cobalt nanowire [409]. The measiued output and transfer characteristics are as good as or better than PPy film field-effect transistors. The gain of the nanowire field-effect transistors could be controlled with successive electrochemical doping of the PPy segment. 

The observed reduction in electron field-effect mobility was then used as an indicator of when the phase segregation process illustrated in Figure 8.8c was taking place. Single OFETs were annealed under high vacuum at temperatures of 130 and 160 °C, and the field-effect mobilities of holes and electrons were measured. The resulting data are plotted in Figure 8.13. Since in this case the measurements are made while at elevated temperatures, the effects of temperature-dependent transport [51, 88] had also to be considered. 

There are two basic types of transistor the bipolar or junction transistor and the field-effect transistor (FET). 

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