Term of the Moment
haptic interface
Redirected from: MODFET
Definition: FET
(Field-Effect Transistor) One of two major categories of transistors. The other is bipolar junction (BJT); however, only a fraction of transistors today are BJT (see diagram below). FETs create an electromagnetic field that turns the transistor on or off when charged. FETs can be fabricated as discrete components or billions can reside on a single chip.
MOSFET (Metal Oxide Semiconductor FET)
The most widely used FETs are MOSFETs. Dating back to the 1960s, MOSFETs come in NMOS (n-channel) and PMOS (p-channel) forms, and when wired in a complementary fashion form CMOS logic. See CMOS, MOSFET and n-type silicon.
FinFET (Fin Field-Effect Transistor)
The type of transistor in chips from 20 to five nanometers. FinFETs emerged in the 2010s and replaced planar MOSFETs in high-end chips. Most FinFETs are designed as CMOS circuits; however, they are no longer state-of-the-art. See FINFET and GAAFET.
JFET/MESFET (Junction/Metal Semiconductor FET)
JFETs and MESFETs are used for analog applications. See JFET.
HEMT (High Electron Mobility Transistor)
Evolving from the MESFET, the HEMT and PHEMT (pseudomorphic HEMT) are used in high-frequency applications. Extremely fast, HEMT varieties include MODFET (modulation doped FET), TEGFET (two-dimensional electron gas FET) and SDHT (selectively doped heterojunction transistor).
CHFET (Complementary Heterostructure FET)
Similar to CMOS, the CHFET is another high-frequency FET using gallium arsenide.
FET vs. Bipolar
FET-based silicon chips are easier to construct than their bipolar (BJT) counterparts. Although FETs switch slower, they use less power because once the gate terminal has been charged, no more current is needed to keep the transistor closed. While the current for one transistor may be negligible, it adds up when billions are switching simultaneously. The heat dissipated by BJT transistors also limits their number on a chip.
FET vs. Bipolar Junction (BJT)
MOSFET (Metal Oxide Semiconductor FET)
The most widely used FETs are MOSFETs. Dating back to the 1960s, MOSFETs come in NMOS (n-channel) and PMOS (p-channel) forms, and when wired in a complementary fashion form CMOS logic. See CMOS, MOSFET and n-type silicon.
FinFET (Fin Field-Effect Transistor)
The type of transistor in chips from 20 to five nanometers. FinFETs emerged in the 2010s and replaced planar MOSFETs in high-end chips. Most FinFETs are designed as CMOS circuits; however, they are no longer state-of-the-art. See FINFET and GAAFET.
JFET/MESFET (Junction/Metal Semiconductor FET)
JFETs and MESFETs are used for analog applications. See JFET.
HEMT (High Electron Mobility Transistor)
Evolving from the MESFET, the HEMT and PHEMT (pseudomorphic HEMT) are used in high-frequency applications. Extremely fast, HEMT varieties include MODFET (modulation doped FET), TEGFET (two-dimensional electron gas FET) and SDHT (selectively doped heterojunction transistor).
CHFET (Complementary Heterostructure FET)
Similar to CMOS, the CHFET is another high-frequency FET using gallium arsenide.
FET vs. Bipolar
FET-based silicon chips are easier to construct than their bipolar (BJT) counterparts. Although FETs switch slower, they use less power because once the gate terminal has been charged, no more current is needed to keep the transistor closed. While the current for one transistor may be negligible, it adds up when billions are switching simultaneously. The heat dissipated by BJT transistors also limits their number on a chip.
After the FET gate is initially charged, no more current is required to keep the transistor closed (turned on). In contrast, BJT gates require charging the entire time the transistor must be closed. See bipolar transistor.