Transistor characteristic

Field effect transistors (FETs), 19 155 22 144, 162-166. See also Transistors characteristics of, 22 164-166 in CMOS logic circuits, 22 251-253 compound semiconductors in, 22 160, 161-162... 

A specially designed transistor was used to investigate the influence of the impurities in PIQ on transistor characteristics. The electrodes of this transistor do not completely cover the contact holes of the emitter and base. This structure is very sensitive to contamination. 

High Purity PIQ Synthesis. PIQ must not degrade device characteristics. The influence of PIQ application on transistor characteristics was evaluated using an npn test... 

In most cases, however, the FET will saturate and operate over the major part of the charging cycle of the LCD as a current-limiting device. In this case, the transistor characteristics can no longer be specified by a minimum ON resistance. Rather we now need to specify the minimum source-drain current /SD. V(t) depends on /SD as... 

Transistors based on a-Si H do not follow the Borkan-Weimer equation (Borkan and Weimer, 1963) since the characteristics of an a-Si H transistor depend on the density of states in the gap. For an exponential density of tail state distribution, appropriate theories were formulated as early as 1975 (Neudeck and Malhotra, 1975, 1976) that have subsequently been developed further (Kishida et al., 1983). If the density of states varies in a nonexponential manner, numerical methods must be used to derive the transistor characteristics. The inverse problem, a derivation of the density of states from field-effect measurements, is discussed in Chapter 2 by Cohen of Volume 21C. 

As a result of trapping, the transistor characteristics are time dependent and quite different when measured under dc (Fig. 9) or pulsed (Fig. 10) conditions. Note that in the latter case the GD Si3N4 gated transistor switches in excess of 30 //A and its performance becomes comparable to the transistors discussed in the preceding chapter. As discussed below, a limited amount of trapping, as long as it is noncumulative, is tolerable and even useful in display TFTs. 

Rashmi, V.R. Balakrishnan, A.K. Kapoor, V. Kumar, S.C. Jain, R. Mertens, S. An-napoorni, Effect of field dependent trap occupancy on organic thin film transistor characteristics, J. Appl. Phys. 94 (2003) 5302-5306. 

Tsujimura, T. (2004). Amorphous/Microciystalline Silicon Thin Film Transistor Characteristics for Large Size OLED Television Driving, fpn. J. Appl. Phys., VoL 43, 5122-5128, ISSN 0021A922... 

In this section the characteristics of transistors using different gate dielectrics will be shown. For the interpretation of the results, the way of determining the transistor characteristics is introduced first. 

All electrical measurements for the electret films were carried out in the group of Hilleringmann in Paderbom. A dark shielded metal box using a HP 4156A parameter semiconductor analyser identified the transistor characteristics. The influence of the interface between the Au top contacts and the Pc film was measured with a Keithley picoamperemeter in darkness as well as under illumination. 

Of course these equations do not account for a field- and charge carrier density dependent mobility, which will result into slight deviations in the transistor characteristics. A similar model which is extended by the field dependent mobility was presented by Smits et al. [4]. Furthermore, the transistor subthreshold behaviour is not represented. Nevertheless, the extended Shockley equations are quite useful for a qualitative interpretation of obtained experimental results. 

In this chapter we investigate and discuss the thermal, optical, electrical properties of the oligothiophene derivatives by means of differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and UV-Vis spectroscopy. The thin films of these compounds produced by solution cast and vacuum deposition methods are characterised by AFM measurements in contact and non-contact mode, and by X-ray diffraction. Finally, an ultra-thin OFET is built, and the transistor characteristics are determined. 

The metal platinum (Pt) is not used in modern microelectronic CMOS applications. As an impurity in silicon, platinum possesses electronic states located close to the middle of the bandgap. It exhibits a high diffusion coefficient and large capture cross sections for minority carriers. Therefore, the presence of platinum would severely change the CMOS transistor characteristics and is not allowed inside a silicon microelectronics fab. 

The evaluation of the sensing properties was achieved by measuring Ids-Vg transfer characteristics in N2 and in a flux of saturated vapors of 1-butanol. A typical example is reported in figure 6a. Figures 6b and 6c show standard transistor characteristics measured while the device was exposed to N2 or to 1-butanol (11250 ppm). 

Anthracene (la)(Figure 3.1.2) is the smallest member of the acene series with reported transistor characteristics. Single-crystal OFETs have shown a mobility of... 

While the longest commercially available oligoacene, pentacene, also exhibits the highest OTFT performance, very few longer acenes or derivatives thereof have been reported. Recently silylethynylated hexacene and heptacene derivatives were synthesized (Figure 3.1.3), but their transistor characteristics were not reported.[78]... 

As with pentacenes, silylethynylated anthradithiophene derivatives (9e-9g) (Figure 3.1.4) with substituents on the central aromatic ring have also been synthesized. [92] OTFTs fabricated with the trimethyl (9e) and triisopropyl (9g) derivatives showed negligible transistor characteristics while those with triethyl derivative (9f) deposited by solution gave a mobility of 1.0 cm V- s" with on/off ratio of 10 . The excellent performance of 9f was attributed to the enhanced Jt-orbital overlap observed in its crystalline thin-film structure. 

Yang, S.Y, Shin, K., and Park, C.E., The effect of gate-dielectric surface energy on pentacene morphology and organic field-effect transistor characteristics, Adv Func. Mat, 15, 1806, 2005. 

However, a major problem with the pentacene precursor method is that a residual amount of the Diels-Alder adduct remains in the film and limits the carrier mobility of the final pentacene film [54]. To limit this problem, pentacene precursors with smaller or more easily eliminated Diels-Alder adducts have recently appeared, but the field-effect transistor characteristics of these new derivatives are yet to be published (Figure 5.3.9c) [55,56]. 

Generally, bias-stress instability refers to long-term changes in the transistor characteristics that do not saturate but continue without limit until the device is rendered useless. Hysteresis refers to short-term reversible shifts in the characteristics that lead to looping in the measured characteristics, depending on the direction in which the bias voltages are swept. There is no sharp distinction between bias-stress instability and hysteresis, and the two may arise from the same or similar physical causes. 

FIGURE 6.4.6 Hysteresis leads to looping transistor characteristics, as seen in the linear-region transfer characteristics of this OTFT made using pentacene on thermal Si02. The drain current is plotted on a linear scale (left-hand vertical axis) and a logarithmic scale (right-hand vertical axis). 

Figure 4. (a) The extrinsic transconductance g as a function of symmetrical contact resistances, (b) The decrease of drive current versus contact resistance, (c) The ideal transistor characteristic compared to (d), where a contact resistance of 50 kOhm is assumed. The circles in (a) and (b) denote the respective values for the case of Rs = Rd =50 kOhm. 

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