upright=1.6, ,_showing_metal_gate">gate_(G),_body_(B),_source_(S),_and_drain_(D)_terminals._The_gate_is_separated_from_the_body_by_an_gate_oxide.html" ;"title="metal_gate.html" ;"title="MOSFET, showing metal gate">gate (G), body (B), source (S), and drain (D) terminals. The gate is separated from the body by an gate oxide">insulating layer (pink).
The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET), also known as the metal–oxide–silicon transistor (MOS transistor, or MOS),
is a type of
insulated-gate field-effect transistor
The field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. FETs (JFETs or MOSFETs) are devices with three terminals: ''source'', ''gate'', and ''drain''. FETs co ...
(IGFET) that is
fabricated by the
controlled oxidation of a
semiconductor
A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way ...
, typically
silicon
Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ...
. The voltage of the
covered gate determines the
electrical conductivity
Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allows ...
of the device; this ability to change conductivity with the amount of applied voltage can be used for
amplifying or
switching electronic
signals.
The MOSFET is the basic building block of most modern
electronics
The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification ...
, and the
most frequently manufactured device in history, with an estimated total of 13
sextillion
Two naming scales for large numbers have been used in English and other European languages since the early modern era: the long and short scales. Most English variants use the short scale today, but the long scale remains dominant in many non-Eng ...
(1.3 × 10
22) MOSFETs manufactured between 1960 and 2018. It is the most common
semiconductor device
A semiconductor device is an electronic component that relies on the electronic properties of a semiconductor material (primarily silicon, germanium, and gallium arsenide, as well as organic semiconductors) for its function. Its conductivit ...
in
digital and
analog circuits
Analogue electronics ( en-US, analog electronics) are electronic systems with a continuously variable signal, in contrast to digital electronics where signals usually take only two levels. The term "analogue" describes the proportional relat ...
, and the most common
power device. It was the first truly compact
transistor that could be miniaturized and mass-produced for a
wide range of uses.
MOSFET scaling and miniaturization has been driving the rapid exponential growth of electronic semiconductor technology since the 1960s, and enable
high-density integrated circuits
An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tin ...
(ICs) such as
memory chips and
microprocessors.
MOSFETs in integrated circuits are the primary elements of
computer processors,
semiconductor memory
Semiconductor memory is a digital electronic semiconductor device used for digital data storage, such as computer memory. It typically refers to devices in which data is stored within metal–oxide–semiconductor (MOS) memory cells on a si ...
,
image sensors, and most other types of integrated circuits. Discrete MOSFET devices are widely used in applications such as
switch mode power supplies,
variable-frequency drives, and other
power electronics applications where each device may be switching thousands of watts. Radio-frequency amplifiers up to the
UHF
Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter (on ...
spectrum use MOSFET transistors as
analog signal and
power amplifiers
An audio power amplifier (or power amp) is an electronic amplifier that amplifies low-power electronic audio signals, such as the signal from a radio receiver or an electric guitar pickup, to a level that is high enough for driving loudspea ...
. Radio systems also use MOSFETs as oscillators, or
mixer
Mixer may refer to:
Electronics
* DJ mixer, a type of audio mixing console used by disc jockeys
* Electronic mixer, electrical circuit for adding signal voltages
* Frequency mixer, electrical circuit that creates new frequencies from two signals ...
s to convert frequencies. MOSFET devices are also applied in audio-frequency power amplifiers for
public address systems,
sound reinforcement
A sound reinforcement system is the combination of microphones, signal processors, amplifiers, and loudspeakers in enclosures all controlled by a mixing console that makes live or pre-recorded sounds louder and may also distribute those sounds ...
, and home and
automobile
A car or automobile is a motor vehicle with wheels. Most definitions of ''cars'' say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people instead of goods.
The year 1886 is regarded ...
sound systems.
MOS integrated circuit (MOS IC)
The MOSFET is the most widely used type of transistor and the most critical device component in
integrated circuit
An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...
(IC) chips.
Planar process, developed by
Jean Hoerni
Jean Amédée Hoerni (September 26, 1924 – January 12, 1997) was a Swiss-American engineer. He was a silicon transistor pioneer, and a member of the "traitorous eight". He developed the planar process, an important technology for reliably fab ...
at
Fairchild Semiconductor in early 1959, was critical to the invention of the monolithic integrated circuit chip by
Robert Noyce later in 1959.
The same year,
Atalla used his surface passivation process to make the first working MOSFET with
Dawon Kahng at Bell Labs.
This was followed by the development of
clean room
A cleanroom or clean room is an engineered space, which maintains a very low concentration of airborne particulates. It is well isolated, well-controlled from contamination, and actively cleansed. Such rooms are commonly needed for scientif ...
s to reduce contamination to levels never before thought necessary, and coincided with the development of
photolithography which, along with surface passivation and the planar process, allowed circuits to be made in few steps.
Atalla realised that the main advantage of a MOS transistor was its ease of
fabrication
Fabrication may refer to:
* Manufacturing, specifically the crafting of individual parts as a solo product or as part of a larger combined product.
Processes in arts, crafts and manufacturing
* Semiconductor device fabrication, the process used ...
, particularly suiting it for use in the recently invented integrated circuits.
In contrast to
bipolar transistors which required a number of steps for the
p–n junction isolation of transistors on a chip, MOSFETs required no such steps but could be easily isolated from each other.
Its advantage for integrated circuits was re-iterated by Dawon Kahng in 1961.
The
Si–
SiO2 system possessed the technical attractions of low cost of production (on a per circuit basis) and ease of integration. These two factors, along with its
rapidly scaling miniaturization and low
energy consumption, led to the MOSFET becoming the most widely used type of transistor in IC chips.
The earliest experimental MOS IC to be demonstrated was a 16-transistor chip built by Fred Heiman and Steven Hofstein at
RCA in 1962.
General Microelectronics later introduced the first commercial MOS integrated circuits in 1964, consisting of 120
p-channel transistors. It was a 20-bit
shift register, developed by Robert Norman
and
Frank Wanlass. In 1967,
Bell Labs
Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984),
then AT&T Bell Laboratories (1984–1996)
and Bell Labs Innovations (1996–2007),
is an American industrial research and scientific development company owned by mul ...
researchers Robert Kerwin, Donald Klein and John Sarace developed the
self-aligned gate
In semiconductor electronics fabrication technology, a self-aligned gate is a transistor manufacturing approach whereby the gate electrode of a MOSFET (metal–oxide–semiconductor field-effect transistor) is used as a mask for the doping of ...
(silicon-gate) MOS transistor, which
Fairchild Semiconductor researchers
Federico Faggin and Tom Klein used to develop the first
silicon-gate MOS IC.
MOS IC chips
There are various different types of MOS IC chips, which include the following.
MOS large-scale integration (MOS LSI)
With its
high scalability,
and much lower power consumption and higher density than bipolar junction transistors,
the MOSFET made it possible to build
high-density IC chips.
By 1964, MOS chips had reached higher
transistor density
The transistor count is the number of transistors in an electronic device (typically on a single substrate or "chip"). It is the most common measure of integrated circuit complexity (although the majority of transistors in modern microprocesso ...
and lower manufacturing costs than
bipolar chips. MOS chips further increased in complexity at a rate predicted by
Moore's law, leading to
large-scale integration (LSI) with hundreds of MOSFETs on a chip by the late 1960s.
MOS technology enabled the integration of more than 10,000 transistors on a single LSI chip by the early 1970s,
before later enabling
very large-scale integration (VLSI).
Microprocessors
The MOSFET is the basis of every
microprocessor
A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circ ...
,
and was responsible for the invention of the microprocessor. The origins of both the microprocessor and the
microcontroller can be traced back to the invention and development of MOS technology. The application of MOS LSI chips to
computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, ...
was the basis for the first microprocessors, as engineers began recognizing that a complete
computer processor could be contained on a single MOS LSI chip.
The
earliest microprocessors were all MOS chips, built with MOS LSI circuits. The first multi-chip microprocessors, the
Four-Phase Systems AL1 in 1969 and the
Garrett AiResearch MP944 in 1970, were developed with multiple MOS LSI chips. The first commercial single-chip microprocessor, the
Intel 4004, was developed by
Federico Faggin, using his silicon-gate MOS IC technology, with
Intel
Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 ser ...
engineers
Marcian Hoff and
Stan Mazor, and
Busicom
was a Japanese company that manufactured and sold computer-related products headquartered in Taito, Tokyo. It owned the rights to Intel's first microprocessor, the Intel 4004, which they created in partnership with Intel in 1970.
Busicom ask ...
engineer
Masatoshi Shima
is a Japanese electronics engineer. He was one of the architects of the world's first microprocessor, the Intel 4004. In 1968, Shima worked for Busicom in Japan, and did the logic design for a specialized CPU to be translated into three-chip ...
. With the arrival of
CMOS
Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss", ) 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 MOSF ...
microprocessors in 1975, the term "MOS microprocessors" began to refer to chips fabricated entirely from
PMOS logic or fabricated entirely from
NMOS logic, contrasted with "CMOS microprocessors" and "bipolar
bit-slice processors".
CMOS circuits
Complementary metal–oxide–semiconductor
Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss", ) 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 MOSF ...
(
CMOS
Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss", ) 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 MOSF ...
) logic was developed by
Chih-Tang Sah
Chih-Tang "Tom" Sah (; born in November 1932 in Beijing, China) is a Chinese-American electronics engineer and condensed matter physicist. He is best known for inventing CMOS (complementary MOS) logic with Frank Wanlass at Fairchild Semiconducto ...
and
Frank Wanlass at
Fairchild Semiconductor in 1963.
CMOS had lower power consumption, but was initially slower than NMOS, which was more widely used for computers in the 1970s. In 1978,
Hitachi
() is a Japanese multinational conglomerate corporation headquartered in Chiyoda, Tokyo, Japan. It is the parent company of the Hitachi Group (''Hitachi Gurūpu'') and had formed part of the Nissan ''zaibatsu'' and later DKB Group and Fuyo G ...
introduced the twin-well CMOS process, which allowed CMOS to match the performance of NMOS with less power consumption. The twin-well CMOS process eventually overtook NMOS as the most common
semiconductor manufacturing process for computers in the 1980s.
By the 1980s CMOS logic consumed over times less power than NMOS logic,
and about 100,000 times less power than bipolar
transistor-transistor logic (TTL).
Digital
The growth of digital technologies like the
microprocessor
A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circ ...
has provided the motivation to advance MOSFET technology faster than any other type of silicon-based transistor. A big advantage of MOSFETs for digital switching is that the oxide layer between the gate and the channel prevents DC current from flowing through the gate, further reducing power consumption and giving a very large input impedance. The insulating oxide between the gate and channel effectively isolates a MOSFET in one logic stage from earlier and later stages, which allows a single MOSFET output to drive a considerable number of MOSFET inputs. Bipolar transistor-based logic (such as
TTL) does not have such a high fanout capacity. This isolation also makes it easier for the designers to ignore to some extent loading effects between logic stages independently. That extent is defined by the operating frequency: as frequencies increase, the input impedance of the MOSFETs decreases.
Analog
The MOSFET's advantages in digital circuits do not translate into supremacy in all
analog circuits. The two types of circuit draw upon different features of transistor behavior. Digital circuits switch, spending most of their time either fully on or fully off. The transition from one to the other is only of concern with regards to speed and charge required. Analog circuits depend on operation in the transition region where small changes to ''V'' can modulate the output (drain) current. The JFET and
bipolar junction transistor (BJT) are preferred for accurate matching (of adjacent devices in integrated circuits), higher
transconductance and certain temperature characteristics which simplify keeping performance predictable as circuit temperature varies.
Nevertheless, MOSFETs are widely used in many types of analog circuits because of their own advantages (zero gate current, high and adjustable output impedance and improved robustness vs. BJTs which can be permanently degraded by even lightly breaking down the emitter-base). The characteristics and performance of many analog circuits can be scaled up or down by changing the sizes (length and width) of the MOSFETs used. By comparison, in bipolar transistors the size of the device does not significantly affect its performance. MOSFETs' ideal characteristics regarding gate current (zero) and drain-source offset voltage (zero) also make them nearly ideal switch elements, and also make
switched capacitor A switched capacitor (SC) is an electronic circuit that implements a function by moving charges into and out of capacitors when electronic switches are opened and closed. Usually, non-overlapping clock signals are used to control the switches, s ...
analog circuits practical. In their linear region, MOSFETs can be used as precision resistors, which can have a much higher controlled resistance than BJTs. In high power circuits, MOSFETs sometimes have the advantage of not suffering from
thermal runaway as BJTs do. Also, MOSFETs can be configured to perform as capacitors and
gyrator circuits which allow op-amps made from them to appear as inductors, thereby allowing all of the normal analog devices on a chip (except for diodes, which can be made smaller than a MOSFET anyway) to be built entirely out of MOSFETs. This means that complete analog circuits can be made on a silicon chip in a much smaller space and with simpler fabrication techniques. MOSFETS are ideally suited to switch inductive loads because of tolerance to
inductive kickback.
Some ICs combine analog and digital MOSFET circuitry on a single
mixed-signal integrated circuit, making the needed board space even smaller. This creates a need to isolate the analog circuits from the digital circuits on a chip level, leading to the use of isolation rings and
silicon on insulator (SOI). Since MOSFETs require more space to handle a given amount of power than a BJT, fabrication processes can incorporate BJTs and MOSFETs into a single device. Mixed-transistor devices are called bi-FETs (bipolar FETs) if they contain just one BJT-FET and
BiCMOS (bipolar-CMOS) if they contain complementary BJT-FETs. Such devices have the advantages of both insulated gates and higher current density.
RF CMOS
In the late 1980s,
Asad Abidi pioneered
RF CMOS technology, which uses MOS
VLSI circuits, while working at
UCLA. This changed the way in which
RF circuits were designed, away from discrete bipolar transistors and towards CMOS integrated circuits. As of 2008, the
radio transceivers in all
wireless networking devices and modern
mobile phones are mass-produced as RF CMOS devices. RF CMOS is also used in nearly all modern
Bluetooth
Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is limi ...
and
wireless LAN (WLAN) devices.
Analog switches
MOSFET analog switches use the MOSFET to pass analog signals when on, and as a high impedance when off. Signals flow in both directions across a MOSFET switch. In this application, the drain and source of a MOSFET exchange places depending on the relative voltages of the source/drain electrodes. The source is the more negative side for an N-MOS or the more positive side for a P-MOS. All of these switches are limited on what signals they can pass or stop by their gate–source, gate–drain, and source–drain voltages; exceeding the voltage, current, or power limits will potentially damage the switch.
Single-type
This analog switch uses a four-terminal simple MOSFET of either P or N type.
In the case of an n-type switch, the body is connected to the most negative supply (usually GND) and the gate is used as the switch control. Whenever the gate voltage exceeds the source voltage by at least a threshold voltage, the MOSFET conducts. The higher the voltage, the more the MOSFET can conduct. An N-MOS switch passes all voltages less than ''V'' − ''V''. When the switch is conducting, it typically operates in the linear (or ohmic) mode of operation, since the source and drain voltages will typically be nearly equal.
In the case of a P-MOS, the body is connected to the most positive voltage, and the gate is brought to a lower potential to turn the switch on. The P-MOS switch passes all voltages higher than ''V'' − ''V'' (threshold voltage ''V'' is negative in the case of enhancement-mode P-MOS).
Dual-type (CMOS)
This "complementary" or CMOS type of switch uses one P-MOS and one N-MOS FET to counteract the limitations of the single-type switch. The FETs have their drains and sources connected in parallel, the body of the P-MOS is connected to the high potential (''V''
DD) and the body of the N-MOS is connected to the low potential (''gnd''). To turn the switch on, the gate of the P-MOS is driven to the low potential and the gate of the N-MOS is driven to the high potential. For voltages between ''V''
DD − ''V''
tn and ''gnd'' − ''V''
tp, both FETs conduct the signal; for voltages less than ''gnd'' − ''V''
tp, the N-MOS conducts alone; and for voltages greater than ''V''
DD − ''V''
tn, the P-MOS conducts alone.
The voltage limits for this switch are the gate–source, gate–drain and source–drain voltage limits for both FETs. Also, the P-MOS is typically two to three times wider than the N-MOS, so the switch will be balanced for speed in the two directions.
Tri-state circuitry sometimes incorporates a CMOS MOSFET switch on its output to provide for a low-ohmic, full-range output when on, and a high-ohmic, mid-level signal when off.
MOS memory
The advent of the MOSFET enabled the practical use of MOS transistors as
memory cell storage elements, a function previously served by
magnetic cores in
computer memory
In computing, memory is a device or system that is used to store information for immediate use in a computer or related computer hardware and digital electronic devices. The term ''memory'' is often synonymous with the term '' primary storag ...
. The first modern computer memory was introduced in 1965, when John Schmidt at
Fairchild Semiconductor designed the first MOS
semiconductor memory
Semiconductor memory is a digital electronic semiconductor device used for digital data storage, such as computer memory. It typically refers to devices in which data is stored within metal–oxide–semiconductor (MOS) memory cells on a si ...
, a
64-bit
In computer architecture, 64-bit integers, memory addresses, or other data units are those that are 64 bits wide. Also, 64-bit CPUs and ALUs are those that are based on processor registers, address buses, or data buses of that size. A ...
MOS
SRAM (static
random-access memory
Random-access memory (RAM; ) is a form of computer memory that can be read and changed in any order, typically used to store working data and machine code. A random-access memory device allows data items to be read or written in almost the ...
).
SRAM became an alternative to
magnetic-core memory
Magnetic-core memory was the predominant form of random-access computer memory for 20 years between about 1955 and 1975.
Such memory is often just called core memory, or, informally, core.
Core memory uses toroids (rings) of a hard magnet ...
, but required six MOS transistors for each
bit of data.
MOS technology is the basis for
DRAM (dynamic
random-access memory
Random-access memory (RAM; ) is a form of computer memory that can be read and changed in any order, typically used to store working data and machine code. A random-access memory device allows data items to be read or written in almost the ...
). In 1966, Dr.
Robert H. Dennard at the
IBM Thomas J. Watson Research Center was working on
MOS memory. While examining the characteristics of MOS technology, he found it was capable of building
capacitors
A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals.
The effect of a ...
, and that storing a charge or no charge on the MOS capacitor could represent the 1 and 0 of a bit, while the MOS transistor could control writing the charge to the capacitor. This led to his development of a single-transistor DRAM memory cell.
In 1967, Dennard filed a patent under IBM for a single-transistor DRAM (dynamic random-access memory) memory cell, based on MOS technology.
MOS memory enabled higher performance, was cheaper, and consumed less power, than
magnetic-core memory
Magnetic-core memory was the predominant form of random-access computer memory for 20 years between about 1955 and 1975.
Such memory is often just called core memory, or, informally, core.
Core memory uses toroids (rings) of a hard magnet ...
, leading to MOS memory overtaking magnetic core memory as the dominant
computer memory
In computing, memory is a device or system that is used to store information for immediate use in a computer or related computer hardware and digital electronic devices. The term ''memory'' is often synonymous with the term '' primary storag ...
technology by the early 1970s.
Frank Wanlass, while studying MOSFET structures in 1963, noted the movement of charge through
oxide onto a
gate. While he did not pursue it, this idea would later become the basis for
EPROM (erasable
programmable read-only memory
A programmable read-only memory (PROM) is a form of digital memory where the contents can be changed once after manufacture of the device. The data is then permanent and cannot be changed. It is one type of read-only memory (ROM). PROMs are used ...
) technology. In 1967,
Dawon Kahng and
Simon Sze proposed that
floating-gate memory cells, consisting of
floating-gate MOSFETs (FGMOS), could be used to produce
reprogrammable ROM (
read-only memory
Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM cannot be electronically modified after the manufacture of the memory device. Read-only memory is useful for storing ...
).
Floating-gate memory cells later became the basis for
non-volatile memory (NVM) technologies including EPROM,
EEPROM
EEPROM (also called E2PROM) stands for electrically erasable programmable read-only memory and is a type of non-volatile memory used in computers, usually integrated in microcontrollers such as smart cards and remote keyless systems, or ...
(electrically erasable programmable ROM) and
flash memory
Flash memory is an electronic non-volatile computer memory storage medium that can be electrically erased and reprogrammed. The two main types of flash memory, NOR flash and NAND flash, are named for the NOR and NAND logic gates. Both use ...
.
Types of MOS memory
There are various different types of MOS memory. The following list includes various different MOS memory types.
MOS sensors
A number of MOSFET
sensors have been developed, for measuring
physical
Physical may refer to:
* Physical examination, a regular overall check-up with a doctor
* ''Physical'' (Olivia Newton-John album), 1981
** "Physical" (Olivia Newton-John song)
* ''Physical'' (Gabe Gurnsey album)
* "Physical" (Alcazar song) (2004)
* ...
,
chemical,
biological and environmental parameters.
The earliest MOSFET sensors include the open-gate FET (OGFET) introduced by Johannessen in 1970,
the
ion-sensitive field-effect transistor (ISFET) invented by
Piet Bergveld in 1970, the
adsorption
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which a ...
FET (ADFET)
patented by P.F. Cox in 1974, and a
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-to ...
-sensitive MOSFET demonstrated by I. Lundstrom, M.S. Shivaraman, C.S. Svenson and L. Lundkvist in 1975.
The ISFET is a special type of MOSFET with a gate at a certain distance,
and where the
metal gate is replaced by an
ion-sensitive
membrane,
electrolyte solution and
reference electrode
A reference electrode is an electrode which has a stable and well-known electrode potential. The high stability of the electrode potential is usually reached by employing a redox system with constant (buffered or saturated) concentrations of ea ...
.
By the mid-1980s, numerous other MOSFET sensors had been developed, including the
gas sensor FET (GASFET), surface accessible FET (SAFET), charge flow transistor (CFT),
pressure sensor FET (PRESSFET),
chemical field-effect transistor A ChemFET is a chemically-sensitive field-effect transistor, that is a field-effect transistor used as a sensor for measuring chemical concentrations in solution. When the target analyte concentration changes, the current through the transistor wi ...
(ChemFET),
reference ISFET (REFET),
biosensor FET (BioFET),
enzyme-modified FET (ENFET) and immunologically modified FET (IMFET).
By the early 2000s, BioFET types such as the
DNA field-effect transistor (DNAFET),
gene-modified FET (GenFET) and
cell-potential BioFET (CPFET) had been developed.
The two main types of
image sensors used in
digital imaging technology are the
charge-coupled device (CCD) and the
active-pixel sensor (CMOS sensor). Both CCD and CMOS sensors are based on MOS technology, with the CCD based on
MOS capacitors and the CMOS sensor based on MOS transistors.
Image sensors
MOS technology is the basis for modern
image sensors, including the
charge-coupled device (CCD) and the CMOS
active-pixel sensor (CMOS sensor), used in
digital imaging and
digital cameras.
Willard Boyle
Willard Sterling Boyle, (August 19, 1924May 7, 2011) was a Canadian physicist. He was a pioneer in the field of laser technology and co-inventor of the charge-coupled device.
As director of Space Science and Exploratory Studies at Bellcomm he h ...
and
George E. Smith developed the CCD in 1969. While researching the MOS process, they realized that an electric charge was the analogy of the magnetic bubble and that it could be stored on a tiny MOS capacitor. As it was fairly straightforward to fabricate a series of MOS capacitors in a row, they connected a suitable voltage to them so that the charge could be stepped along from one to the next.
The CCD is a semiconductor circuit that was later used in the first
digital video cameras for
television broadcasting.
The MOS
active-pixel sensor (APS) was developed by Tsutomu Nakamura at
Olympus
Olympus or Olympos ( grc, Ὄλυμπος, link=no) may refer to:
Mountains
In antiquity
Greece
* Mount Olympus in Thessaly, northern Greece, the home of the twelve gods of Olympus in Greek mythology
* Mount Olympus (Lesvos), located in Le ...
in 1985.
The CMOS active-pixel sensor was later developed by
Eric Fossum and his team at
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeedin ...
's
Jet Propulsion Laboratory
The Jet Propulsion Laboratory (JPL) is a Federally funded research and development centers, federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, La Cañada Flintridge, California ...
in the early 1990s.
[Eric R. Fossum (1993), "Active Pixel Sensors: Are CCD's Dinosaurs?" Proc. SPIE Vol. 1900, p. 2–14, ''Charge-Coupled Devices and Solid State Optical Sensors III'', Morley M. Blouke; Ed.]
MOS image sensors are widely used in
optical mouse
An optical mouse is a computer mouse which uses a light source, typically a light-emitting diode (LED), and a light detector, such as an array of photodiodes, to detect movement relative to a surface. Variations of the optical mouse have largely r ...
technology. The first optical mouse, invented by
Richard F. Lyon
Richard "Dick" Francis Lyon (born 1952) is an American inventor, scientist, and engineer. He is one of the two people who independently invented the first optical mouse devices in 1980. He has worked in many aspects of signal processing and wa ...
at
Xerox
Xerox Holdings Corporation (; also known simply as Xerox) is an American corporation that sells print and digital document products and services in more than 160 countries. Xerox is headquartered in Norwalk, Connecticut (having moved from St ...
in 1980, used a
5µm NMOS sensor chip.
Since the first commercial optical mouse, the
IntelliMouse introduced in 1999, most optical mouse devices use CMOS sensors.
Other sensors
MOS
sensors, also known as MOSFET sensors, are widely used to measure
physical
Physical may refer to:
* Physical examination, a regular overall check-up with a doctor
* ''Physical'' (Olivia Newton-John album), 1981
** "Physical" (Olivia Newton-John song)
* ''Physical'' (Gabe Gurnsey album)
* "Physical" (Alcazar song) (2004)
* ...
,
chemical,
biological and environmental parameters.
The
ion-sensitive field-effect transistor (ISFET), for example, is widely used in
biomedical applications.
MOSFETs are also widely used in
microelectromechanical systems (MEMS), as silicon MOSFETs could interact and communicate with the surroundings and process things such as
chemicals,
motions and light.
An early example of a MEMS device is the resonant-gate transistor, an adaptation of the MOSFET, developed by
Harvey C. Nathanson in 1965.
Common applications of other MOS sensors include the following.
Power MOSFET
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_
Surface-mount_technology_(SMT),_originally_called_planar_mounting,_is_a_method_in_which_the_electrical_components_are_mounted_directly_onto_the_surface_of_a__printed_circuit_board_(PCB)._An_electrical_component_mounted_in_this_manner_is_referre_...
_packages._Operating_as_switches,_each_of_these_components_can_sustain_a_blocking_voltage_of_120