A transistor is a semiconductor device used to amplify or switch electrical signals and power. It is one of the basic building blocks of modern electronics. It is composed of semiconductor material,usually with at least three terminals for connection to an electronic circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power,a transistor can amplify a signal. Some transistors are packaged individually,but many more in miniature form are found embedded in integrated circuits. Because transistors are the key active components in practically all modern electronics,many people consider them one of the 20th century's greatest inventions.
The metal-oxide-semiconductor field-effect transistor is a type of field-effect transistor (FET),most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate,the voltage of which determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals. A metal-insulator-semiconductor field-effect transistor (MISFET) is a term almost synonymous with MOSFET. Another synonym is IGFET for insulated-gate field-effect transistor.
N-type metal–oxide–semiconductor logic uses n-type (-) MOSFETs to implement logic gates and other digital circuits. These nMOS transistors operate by creating an inversion layer in a p-type transistor body. This inversion layer,called the n-channel,can conduct electrons between n-type "source" and "drain" terminals. The n-channel is created by applying voltage to the third terminal,called the gate. Like other MOSFETs,nMOS transistors have four modes of operation:cut-off,triode,saturation,and velocity saturation.
Complementary metal–oxide–semiconductor is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSFETs for logic functions. CMOS technology is used for constructing integrated circuit (IC) chips,including microprocessors,microcontrollers,memory chips,and other digital logic circuits. CMOS technology is also used for analog circuits such as image sensors,data converters,RF circuits,and highly integrated transceivers for many types of communication.
An insulated-gate bipolar transistor (IGBT) is a three-terminal power semiconductor device primarily forming an electronic switch. It was developed to combine high efficiency with fast switching. It consists of four alternating layers (P–N–P–N) that are controlled by a metal–oxide–semiconductor (MOS) gate structure.
In semiconductor manufacturing,silicon on insulator (SOI) technology is fabrication of silicon semiconductor devices in a layered silicon–insulator–silicon substrate,to reduce parasitic capacitance within the device,thereby improving performance. SOI-based devices differ from conventional silicon-built devices in that the silicon junction is above an electrical insulator,typically silicon dioxide or sapphire. The choice of insulator depends largely on intended application,with sapphire being used for high-performance radio frequency (RF) and radiation-sensitive applications,and silicon dioxide for diminished short-channel effects in other microelectronics devices. The insulating layer and topmost silicon layer also vary widely with application.
The threshold voltage,commonly abbreviated as Vth or VGS(th),of a field-effect transistor (FET) is the minimum gate-to-source voltage (VGS) that is needed to create a conducting path between the source and drain terminals. It is an important scaling factor to maintain power efficiency.
A fin field-effect transistor (FinFET) is a multigate device,a MOSFET built on a substrate where the gate is placed on two,three,or four sides of the channel or wrapped around the channel,forming a double or even multi gate structure. These devices have been given the generic name "FinFETs" because the source/drain region forms fins on the silicon surface. The FinFET devices have significantly faster switching times and higher current density than planar CMOS technology.
A power MOSFET is a specific type of metal–oxide–semiconductor field-effect transistor (MOSFET) designed to handle significant power levels. Compared to the other power semiconductor devices,such as an insulated-gate bipolar transistor (IGBT) or a thyristor,its main advantages are high switching speed and good efficiency at low voltages. It shares with the IGBT an isolated gate that makes it easy to drive. They can be subject to low gain,sometimes to a degree that the gate voltage needs to be higher than the voltage under control.
Hot carrier injection (HCI) is a phenomenon in solid-state electronic devices where an electron or a “hole”gains sufficient kinetic energy to overcome a potential barrier necessary to break an interface state. The term "hot" refers to the effective temperature used to model carrier density,not to the overall temperature of the device. Since the charge carriers can become trapped in the gate dielectric of a MOS transistor,the switching characteristics of the transistor can be permanently changed. Hot-carrier injection is one of the mechanisms that adversely affects the reliability of semiconductors of solid-state devices.
A multigate device,multi-gate MOSFET or multi-gate field-effect transistor (MuGFET) refers to a metal–oxide–semiconductor field-effect transistor (MOSFET) that has more than one gate on a single transistor. The multiple gates may be controlled by a single gate electrode,wherein the multiple gate surfaces act electrically as a single gate,or by independent gate electrodes. A multigate device employing independent gate electrodes is sometimes called a multiple-independent-gate field-effect transistor (MIGFET). The most widely used multi-gate devices are the FinFET and the GAAFET,which are non-planar transistors,or 3D transistors.
Drain-induced barrier lowering (DIBL) is a short-channel effect in MOSFETs referring originally to a reduction of threshold voltage of the transistor at higher drain voltages. In a classic planar field-effect transistor with a long channel,the bottleneck in channel formation occurs far enough from the drain contact that it is electrostatically shielded from the drain by the combination of the substrate and gate,and so classically the threshold voltage was independent of drain voltage. In short-channel devices this is no longer true:The drain is close enough to gate the channel,and so a high drain voltage can open the bottleneck and turn on the transistor prematurely.
The MASTAR is an analytical model of Metal-Oxide Semiconductor Field-Effect Transistors,developed using the voltage-doping transformation (VDT) technique. MASTAR offers good accuracy and continuity in current and its derivatives in all operation regimes of the MOSFET devices. The model has been successfully used in CAD/EDA simulation tools.
The subthreshold slope is a feature of a MOSFET's current–voltage characteristic.
Polysilicon depletion effect is the phenomenon in which unwanted variation of threshold voltage of the MOSFET devices using polysilicon as gate material is observed,leading to unpredicted behavior of the electronic circuit. Because of this variation High-k Dielectric Metal Gates (HKMG) were introduced to solve the issue.
The tunnel field-effect transistor (TFET) is an experimental type of transistor. Even though its structure is very similar to a metal–oxide–semiconductor field-effect transistor (MOSFET),the fundamental switching mechanism differs,making this device a promising candidate for low power electronics. TFETs switch by modulating quantum tunneling through a barrier instead of modulating thermionic emission over a barrier as in traditional MOSFETs. Because of this,TFETs are not limited by the thermal Maxwell–Boltzmann tail of carriers,which limits MOSFET drain current subthreshold swing to about 60 mV/decade of current at room temperature.
The field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. It comes in two types:junction-gate FET (JFET) and metal-oxide-semiconductor FET (MOSFET). FETs have three terminals:source,gate,and drain. FETs control the flow of current by the application of a voltage to the gate,which in turn alters the conductivity between the drain and source.
A field-effect transistor-based biosensor,also known as a biosensor field-effect transistor,field-effect biosensor (FEB),or biosensor MOSFET,is a field-effect transistor that is gated by changes in the surface potential induced by the binding of molecules. When charged molecules,such as biomolecules,bind to the FET gate,which is usually a dielectric material,they can change the charge distribution of the underlying semiconductor material resulting in a change in conductance of the FET channel. A Bio-FET consists of two main compartments:one is the biological recognition element and the other is the field-effect transistor. The BioFET structure is largely based on the ion-sensitive field-effect transistor (ISFET),a type of metal–oxide–semiconductor field-effect transistor (MOSFET) where the metal gate is replaced by an ion-sensitive membrane,electrolyte solution,and reference electrode.
Deblina Sarkar is an Indian physicist,electrical engineer,and inventor. She is an assistant professor at the Massachusetts Institute of Technology (MIT) and the AT&T Career Development Chair Professor of the MIT Media Lab. Sarkar has been internationally recognized for her invention of an ultra thin quantum mechanical transistor that can be scaled to nano-sizes and used in nanoelectronic biosensors. As the principal investigator of the Nano Cybernetic Biotrek Lab at MIT,Sarkar leads a multidisciplinary team of researchers towards bridging the gap between nanotechnology and synthetic biology to build new nano-devices and life-machine interfacing technologies with which to probe and enhance biological function.
