Electron field-effect mobility

Empolying such a Ca passivated Si02 insulator in combination with Ca drain-source electrodes, n-t5q3c pentacene OFETs can be realised as has been demonstrated by Ahles et al. [29]. This, however, holds only for thin Ca layers as will be shown in the following, where the influence of the Ca passivation thickness on the electron transport in pentacene OFETs is discussed. Illustrated in Figiue 24.8 is the electron field effect mobility in dependence of the Ca thickness. By eonsidering the mobility of pristine devices, which have not... 

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. 

To relate the measured electron field-effect mobility to the concentration of fuller-ene molecules at the semiconductor-dielectric interface, an implementation of percolation theory was employed [106]. Details of the derivation are given elsewhere [101], but it was found that the following equation gave an adequate description of the relationship (when fullerene aggregation is neglected) ... 

Here jUe is the electron field-effect mobility, c is the fullerene site occupation probability (c = Cl Co), p is the bond occupation probability, pc is the threshold bond occupation probability for percolation, a is the wavefunction overlap parameter of the fullerene molecules, and a is given by the following function ... 

By converting the measured electron field-effect mobilities in Figure 8.17a into concentrations using Eq. (8.6), the solution to the diffusion equation (Eq. (8.5)) could be fitted to the data and an approximate diffusion coefficient of D = 5 nm s could be extracted for [60JPCBM in P3HTat a temperature of 130 °C. 

Fig. 14 Electron field-effect mobility and threshold voltage in dependence on the Ca interlayer thickness. The inset shows the layout of the measured devices. The values have been obtained for devices unexposed to thermal or electrical stress. A cyclic electrical stress leads to an improvement of the device characteristics with a maximal electron field-effect mobility of 0.17cm s and...

Chen, C.-Y. Kanicki, J. 1996. High field-effect-mobility a-Si H TFT based on high deposition rate PECVD materials. IEEE Electron Device Lett. 17 437-439. 

Fig. 6 (a) Scanning electron and (b) atomic force microscopy images of copper phthalocyanine Langmuir-Blodgett monolayer FETs. (c) Hole field-effect mobility as a function of the copper phthalocyanine channel length... 

The synthesis, characterization, electrical conductivity, and field effect mobility of a series of novel soluble N-alkyl dithieno[3,2-b 2, 3 -d]pyrrole (DTP) and thiophene (TH)-based copolymers (DTP-co-THs) were reported (06MM1771 08JA13167). The incorporation of DTP units extends n conjugation, and the introduction of thiophene subunits imparts good solubility, high conductivity, and high charge carrier mobility. Therefore, the incorporation of DTP units and various substituted thiophenes into the polymer backbone affords the ability to enhance the solubility, lower the band gap, and achieve the enhanced electronic properties. 

Figure 12.9 shows the output and transfer characteristics of a state-of-the-art, polymer FET fabricated using the Plastic Logic direct-write manufacturing process (L = 10 pm). No encapsulation of the TFT is present other than what is naturally provided by the presence of the PET substrate on the bottom and an inkjet printed silver gate electrode on the top. The device exhibits a field-effect mobility of 0.04 cm2 V 1 s 1 and ON-OFF current ratio of 5 x 10s. The threshold potential is Vt = 5-6 V. These basic TFT performance values can be achieved consistently in a manufacturing environment, and are sufficient to drive a 100 dpi electronic paper display with A5 size. 

Geens W, Shaheen SE, Brabec CJ, Poortmans J, Sariciftci NS (2000) Field-effect mobility measurements of conjugated polymer/fullerene photovoltaic blends. Presented at the electronic properties of novel materials—molecular nanostructures, 14th international winter school/Euroconference (American Institute of Physics), Kirchberg... 

In Fig. 1(b) we present an effective field-effect mobility vs. pentacene layer thickness in the samples fabricated by the deposition rate 0.05 nm/min. We see that at such low growth rates the charge transport mechanisms evolve differently than at the elevated growth rates. The most prominent feature is marked plateau in mobility at the pentacene layer thickness range between 3 nm and 10 nm. The differences in the electronic transport are reflected also in the pentacene morphology near the metal/OS interface. 

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