MISFET Field Effect Transistor

MISFET. See Metal insulator semiconductor field-effect transistor. 

MISFETs), 22 162, 192. See also Field effect transistors (FETs) Metal-insulator-semiconductor junction, 23 34... 

Device motivation for interface studies, and Optical absorption and emission in conjugated oligomers and polymers. The principles of device physics of metal insulator field-effect transistors (MISFETs) and light emitting diodes (LEDs) are oudined mainly as motivation for the contents of the chapters which follow, but also to point out certain features relevant to developing an understanding of the nature of the polymer-metal interface (chapters 5 and 6). The basic principles of electro-luminescence are reviewed here, at the level consistent with the aims of this work. 

Gallium arsenide s native oxide is found to be a mixture of nonstoichiometric galhum and arsenic oxides and elemental arsenic. Thus, the electronic band structure is found to be severely disrupted, causing a breakdown in normal semiconductor behavior on the GaAs surface. As a consequence, the GaAs MISFET (metal insulator semiconductor field-effect transistor) equivalent to the technologically important Si-based MOSFET (metal-oxide semiconductor field-effect transistor) is, therefore, presently unavailable. 

Figure 14-6. Schematic view of three kinds of field-effect transistors (FET) (a) metal-insulator-semiconductor FET (MISFET), (b) metal-semiconductor FET (MESFET), (c) thin-film transistor (TFT).

The MIS capacitor represents the heart of most field effect sensor devices, and the physics of MIS capacitors is of importance and is treated in semiconductor physics and other sensor books (Sze, 1981 Lundstrom, 1995 Dimitrijev, 2000). Here, we will only give the basic physical principles regarding the metal insulator semiconductor field effect transistor (MISFET), since this is the ultimate transducer for commercial sensor devices. 

MIS field-effect transistors (MISFETs) and enzyme field-effect transistors (ENFETs) based on conducting polymers have also been fabricated. A schematic diagram of such a device is shown in Figure 13.12. Janata and co-workers have investigated the electrical properties... 

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-... 

Fig. 5. Metal-insulated semiconductor field effect transistor with n-channel (n-MISFET). (A) the state with uncharged G-I-Su capacitor, (B) open transistor with charged G-I-Su capacitor. Abbreviations S, source electrode D, drain electrode G, gate electrode Su, substrate Al, aluminium contact I, insulator (dielectric) n-Si, p-Si, n- or p-type of silicone...

The use of semiconducting conjugated polymers as an electro-active material in microelectronic devices is a rapidly growing area. Burroughes et al. [248] reported the first examples of high-performance Schottky diodes, metal-insulator semiconductor (MIS) diodes and the MIS-field effect transistor (MISFET) structure involving conjugated polymers. 

Electrically conducting polymers can be used as the active element in metal-insulator-semiconductor field-effect transistors (MISFET). MISFETs are generally produced by spin-coating a solution of a polymer onto the surface of oxidized silicon onto which metal electrodes have previously been deposited to form source and drain contacts (Fig. 21) [765]. 

Figure 1. (a) Schematic drawing of a metaHnsulator (Si02)-semiconductor field effect transistor (MISFET). The insulator and gate metal are typically 100 nm thick. The channel length, the distance between the n-regions, is typically of the order of 1-10 pm and the channel width (the dimension perpendicular to the paper) 10-100 pm... 

One of the earliest examples of a conjugated polymer electronic device used transpolyacetylene which had been prepared by the Durham route. Precursor polyma- 2 has very good film-forming properties, and it is simple to control the thickness of the final polyacetylene film. Durham polyacetylene has electrical characteristics that are well suited to device fabrication. The carrier concentration (of the order 10 cm-s) results from unintentional doping, most likely from immobile catalyst residues that are chemically bound to the polymer chain ends. The undoped polymer can take over the role of the semiconductor in a metal-insulator-semiconductor field-effect transistor (MISFET). ... 

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. 

The three-terminal field effect transistor allows measurement of the conductance of the surface charge layer, and we have used a variety of device structures including that shown in figure 3. The source and drain contacts on the top of this structure allow the setting of the electric field across the insulator by defining the voltage of the gate (Vgs) and also allow measurement of the conductance of the channel between source and drain. We defer to section 7 discussion of the standard conditions for the operation of the MISFET. 

The MIS Field Effect Transistor, or MISFET, operates by modulation of the conductance of the semiconductor in the depletion, accumulation or inversion modes, with... 

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