Field-effect transistor output characteristics

Fig. 2.19. (a) Scheme of a transparent field effect transistor based on ZnO [191]. The gate electrode consists of tin-doped indium oxide (ITO) and the gate dielectric is a multilayer of AECE/TiCE (ATO). (b) Output characteristics (drain-source current as a function of the drain-source voltage) for different gate voltages. The saturation current is about 530 rA at a gate bias of 40 V. From this output characteristics a threshold voltage of 19 V and a field-effect mobility of 27 cm2 V-1 s-1 were calculated [192]... 

The transmitter amplifier chain consists of a linear, three-stage transistor amplifier from Amplifier Research (10 W), a class C single-stage field effect transistor (FET) amplifier (120 W) custom-built by H. Bonn GmbH, Munich, and a final tube amplifier with two tetrodes 4CX 350A that deliver more than 1.5 kW of pulse power. A special effort was made to match the input and output impedances of this tube amplifier to the characteristic impedance (50 ( ) of the cables connecting it with the probe and the driver, respectively. This impedance matching resulted in the virtually complete disappearance of antisymmetric phase transients (for a discussion of the effects of such phase transients on m.p. spectra, see Haeberlen, 1976, Appendix D). 

Figure 17.3 Output and transfer characteristics of unipolar field-effect transistors with neat Cso (a, c) and neat CuPc (b, d) films. The substrates were treated with 02-plasma and the films evaporated at 375 K substrate temperature. The direction of the hysteresis is indicated by arrows. (Figure adopted from Ref. [27].)...

The effect of stretching the junction on the eurrent voltage characteristic is shown in Figure 12.13. If the tip position is identified with a gate voltage, the graph indeed looks like the output characteristies of a field effect transistor. 

Flexible picene thin film field-effect transistors have been fabricated using a gate dielectric from poly(tetra-lluoro-/7-xylylene) on a poly(ethylene terephthalate) substrate [39]. These field-effect transistors show /I-channel output/transfer characteristics. A sensing effect for oxygen is observed. The hysteresis in the transfer curves is negligible. The parylene gate can eliminate a reduction in the drain current. 

Fig. 29 a Top contact and b bottom contact field-effect transistor structures for determination of charge-transport properties of organic semiconductors, c Typical output characteristics and d transfer characteristics of an organic field-effect transistor with Spiro-TAD 61 as active material (measurements by T.P.l. Saragi)... 

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. 

Figure 13.16 shows a SiNW 4 p.m in length and 9.5 nm in width. Figure 13.16a shows the silicon oxide mask. The thickness of the fabricated mask is about 3 nm. After etching, the SiNW is contacted to two platinum electrodes (Fig. 13.16b). The fabricated SiNW is the main element of a field-effect transistor formed by introducing a gate electrode. Here, the gate electrode is situated at the back of a silicon-on-insulator wafer. The output and transfer characteristics of the transistor formed with the SiNW described above are shown in Fig. 13.16d. The output curve (left panel) shows a clear dependence on the gate voltage. The off-state drain current leakage is about 10 A. The device shown above has an on/off current ratio of 10, and it can be used to develop very sensitive biomolecular sensors.

Fig. 2 (a) Output and (b) transfer characteristics of a near-ideal organic field-effect transistor in hole accumulation, (c) Extraction of mobility and threshold voltage from the square root plot of the saturation current... 

Olhls have also been applied to the detection of redox gases. For example, Lee et al. demonstrated a PANI-based OTFT ammonia sensor and analyzed its performance. Ammonia concentration was obtained from the variation of the drain current of the transistor. In the absence of analyte, the output characteristics (Figure 13(a)) were consistent with operation as a p-channel depletion-mode field-effect transistor. When the OTFT was tested in various ammonia concentrations, the data show that the drain current saturation level was sensitive to ammonia concentration. Figure 13(b) shows the result of interactions of the OTFT with ammonia concentrations from air (0 ppm) up to... 

Figure 14 Field-effect transistor gas sensor (a, b) device schematics (c, d) output characteristics for poly-DPOT and poly-DDT (e, f) response to 700 ppm ethanol and 700 ppm 1-hexanol and (g) relative response to the analytes. S, Source D, drain G, Gate WG, gate width. Reproduced with permission from Torsi, L. Tafuri, A. etal. Sens. Actuators, B2003, 93 (1-3), 257-262. ...

Typical transfer and output characteristics of a solution-processed pentacene FET with channel length L = 20 pm and W = 1000 pm are shown in Fig. 13.7. The characteristics were obtained under ambient conditions. The field effect mobility of the FET is 0.01 cm2 V-1 s-1 at Vg = —20 V. On less typical wafers mobilities as high as 0.25 cm2 V-1 s 1 have been observed. The drain current modulation 1d(Vd = —1 V, Vg = -20 V)/ID(VD = —1 V, VG = 10 V) of 10s is routinely obtained. By improving the uniformity and by reducing the parameter spread the integration level could be increased to about 103 transistors. 

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