Unipolar Field-Effect Transistors

The analysis of the shown transfer characteristics yielded saturation mobilities for these preparation conditions (O2 plasma treatment, 375 K during evaporation) of 7 x cmWs for the Cgo FET and 6x10 cmWs for the CuPc FET. The threshold voltages were -1- 63 V and - 31 V, respectively. 

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W. Shockley, Unipolar Field-effect transistor, Proc. IRE 40 1365-1376 (Nov 1952). 

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 surface FET was proposed by Lilienfeld42 [23] and by Heil43 [24]. The junction unipolar or field-effect transistor (JFET) was proposed by... 

Figure 17.1 Sketch for the unipolar and ambipolar operation regimes of an organic field-effect transistor.

Field effect transistors In the fabrication of some potentiometric and gas-sensitive biochemical sensors an important role is played by unipolar transistors controlled by an electrical field (field effect transistors, FET) with a conducting channel isolated from the control electrode (gate) by a thin layer of insulator (MISFET-metal insulated semiconductor FET) made of Si02 (MOSFET-metal oxide semicon-... 

Unipolar Transistor Uses electrons only or holes only field effect transistor. 

The source and drain are both p-type if the current flowing is holes. Surface field effect transistors have become the dominant type of transistor used in integrated circuits, which can contain up to one billion transistors plus resistors, capacitors, and the very thinnest of deposited connection wires made from aluminum, copper, or gold. The field effect transistors are simpler to produce than junction transistors and have many fevorable electrical characteristics. The names of various field effect transistors go by the abbreviations MOS (metal-oxide semiconductor), PMOS (p-type metal-oxide semiconductor), NMOS (n-type metal-oxide semiconductor), CMOS (complementary metal-oxide semiconductor—uses both p-type unipolar and n-type unipolar). 

OFETs. On the other hand, unipolar n- or p-type transistors can be seen as am-bipolar OFETs where the fragile balance in the hole and electron injection and/or transport properties is sufficiently disturbed. Hence, a controlled engineering of the transport and injection properties starting from ambipolar acting OFETs appears to be a promising route to obtain complementary OFETs for CMOS devices. Whether a field-effect transistor acts ambipolar, unipolar p-type or unipolar n-type depends beside the applied voltages on ... 

Fig. 16 Electron and hole field-effect mobilities of pentacene-based OEETs for different polymeric gate dielectrics depicted in Fig. 15. The respective mobilities have been extracted from transfer characteristics of either unipolar p-channel or unipolar n-channel transistors. For one gate dielectric gold or Ca source/drain metals have been used to define the polarity of the field-effect transistors...

Apparently, for Vm = 0 V the entire potential Vdd determines Vout and Vout = OV is calculated for Vjn = Vaj. This is only possible as long as truly unipolar OFETs have been employed with a rather low off current. Then, at the logical 1 and the logical 0, evanescent voltage losses prevail. The situation changes if the used OFETs show weak ambipolar character since the field-effect transistors lose their ability to close completely. This is when ju and/or jUn are not zero. In Fig. 21 simulated characteristics from an inverter are depicted, where ambipolar transistors have been... 

Field effect transistors (FETs) work on an entirely different principle than junction transistors. These devices are sometimes called unipolar devices since only one type of carrier is involved. Although they are much simpler and faster than junction transistors, their development did not begin as early because specialized methods and controls had to be invent for their manufacture. 

We have found that the polymer prepared in this way is very well suited for use in semiconductor device structures in which a semiconductor of one carrier type only is required (unipolar devices). The polymer as prepared is extrinsically doped with p-type carriers, to a concentration in the range lO to 10 8 cm 3, and these dopants are not readily mobile under the applied electric fields within these structures. We have made and measured Schottky-barrier diodes, MIS (Metal Insulator Semiconductor) diodes and MISFETs (MIS Field Effect Transistors), and it is the results of these investigations, some of which are published elsewhere [11-17], which are presented in the present chapter. 

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