Metal transistor

Silicon micromachined semiconductor gas sensors are mainly packaged using standard metallic transistor outline (TO) headers as support, and wire bonding is used for their electrical connection. Typically, a metallic cap with a grid is fixed to the TO header with a hydrophobic gas permeable membrane on top of it. A filtering agent can be also included in the package. 

Figure Bl.22.4. Differential IR absorption spectra from a metal-oxide silicon field-effect transistor (MOSFET) as a fiinction of gate voltage (or inversion layer density, n, which is the parameter reported in the figure). Clear peaks are seen in these spectra for the 0-1, 0-2 and 0-3 inter-electric-field subband transitions that develop for charge carriers when confined to a narrow (<100 A) region near the oxide-semiconductor interface. The inset shows a schematic representation of the attenuated total reflection (ATR) arrangement used in these experiments. These data provide an example of the use of ATR IR spectroscopy for the probing of electronic states in semiconductor surfaces [44]-...

MESFET. See Metal semiconductor field-effect transistor. 

Metal oxide semiconductor field-effect transistor pOSFEQ... 

Semiconductors are materials that are characterized by resistivities iatermediate between those of metals and of iasulators. The study of organic semiconductors has grown from research on conductivity mechanisms and stmcture—property relationships ia soHds to iaclude appHcations-based research on working semiconductor junction devices. Organic materials are now used ia transistors, photochromic devices, and commercially viable light-emitting diodes, and the utility of organic semiconductors continues to iacrease. 

Gate oxide dielectrics are a cmcial element in the down-scaling of n- and -channel metal-oxide semiconductor field-effect transistors (MOSEETs) in CMOS technology. Ultrathin dielectric films are required, and the 12.0-nm thick layers are expected to shrink to 6.0 nm by the year 2000 (2). Gate dielectrics have been made by growing thermal oxides, whereas development has turned to the use of oxide/nitride/oxide (ONO) sandwich stmctures, or to oxynitrides, SiO N. Oxynitrides are formed by growing thermal oxides in the presence of a nitrogen source such as ammonia or nitrous oxide, N2O. Oxidation and nitridation are also performed in rapid thermal processors (RTP), which reduce the temperature exposure of a substrate. 

Interface states played a key role in the development of transistors. The initial experiments at Bell Laboratories were on metal/insulator/semiconductor (MIS) stmctures in which the intent was to modulate the conductance of a germanium layer by applying a voltage to the metal plate. However, only - 10% of the induced charges were effective in charging the conductance (3). It was proposed (2) that the ineffective induced charges were trapped in surface states. Subsequent experiments on surface states led to the discovery of the point-contact transistor in 1948 (4). 

Considerable interest in the sohd-state physics of sihcon carbide, that is, the relation between its semiconductor characteristics and crystal growth, has resulted from the expectation that SiC would be useflil as a high temperature-resistant semiconductor in devices such as point-contact diodes (148), rectifiers (149), and transistors (150,151) for use at temperatures above those where sihcon or germanium metals fail (see Semiconductors). 

Instruments based on the contact principle can further be divided into two classes mechanical thermometers and electrical thermometers. Mechanical thermometers are based on the thermal expansion of a gas, a liquid, or a solid material. They are simple, robust, and do not normally require power to operate. Electrical resistance thermometers utilize the connection between the electrical resistance and the sensor temperature. Thermocouples are based on the phenomenon, where a temperature-dependent voltage is created in a circuit of two different metals. Semiconductor thermometers have a diode or transistor probe, or a more advanced integrated circuit, where the voltage of the semiconductor junctions is temperature dependent. All electrical meters are easy to incorporate with modern data acquisition systems. A summary of contact thermometer properties is shown in Table 12.3. 

Nonstoichiometric oxide phases are of great importance in semiconductor devices, in heterogeneous catalysis and in understanding photoelectric, thermoelectric, magnetic and diffusional properties of solids. They have been used in thermistors, photoelectric cells, rectifiers, transistors, phosphors, luminescent materials and computer components (ferrites, etc.). They are cmcially implicated in reactions at electrode surfaces, the performance of batteries, the tarnishing and corrosion of metals, and many other reactions of significance in catalysis. ... 

Contacts are the elementary building blocks for all electronic devices. These include interfaces between semiconductors of different doping type (homojunctions) or of different composition (heterojunctions), and junctions between a metal and a semiconductor, which can be either rectifying (Schotlky junction) or ohmic. Because of their primary importance, the physics of semiconductor junctions is largely dealt with in numerous textbooks [11, 12]. We shall concentrate here on basic aspects of the metal-semiconductor (MS) and, above all, metal-insulator-semiconductor (MIS) junctions, which arc involved in the oiganic field-effect transistors. 

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