FETs can be either n-channel or p-channel. It gets pretty complicated.
Types of field-effect transistors[edit]
Depletion-type FETs under typical voltages: JFET, poly-silicon MOSFET, double-gate MOSFET, metal-gate MOSFET, MESFET. depletion , electrons , holes , metal , insulator . Top=source, bottom=drain, left=gate, right=bulk. Voltages that lead to channel formation are not shown.
The channel of a FET is doped to produce either an n-type semiconductor or a p-type semiconductor. The drain and source may be doped of opposite type to the channel, in the case of depletion mode FETs, or doped of similar type to the channel as in enhancement mode FETs. Field-effect transistors are also distinguished by the method of insulation between channel and gate. Types of FETs include:
The CNTFET (carbon nanotube field-effect transistor).
The DEPFET is a FET formed in a fully depleted substrate and acts as a sensor, amplifier and memory node at the same time. It can be used as an image (photon) sensor.
The DGMOSFET (dual-gate MOSFET) is a FET with two insulated gates.
The DNAFET (DNA field-effect transistor) is a specialized FET that acts as a biosensor, by using a gate made of single-strand DNA molecules to detect matching DNA strands.
The FREDFET (fast-reverse or fast-recovery epitaxial diode FET) is a specialized FET designed to provide a very fast recovery (turn-off) of the body diode.
The HEMT (high-electron-mobility transistor), also called a HFET (heterostructure FET), can be made using bandgap engineering in a ternary semiconductor such as AlGaAs. The fully depleted wide-band-gap material forms the isolation between gate and body.
The HIGFET (heterostructure insulated gate field-effect transisitor) is now used mainly in research. [1]
The IGBT (insulated-gate bipolar transistor) is a device for power control. It has a structure akin to a MOSFET coupled with a bipolar-like main conduction channel. These are commonly used for the 200–3000 V drain-to-source voltage range of operation. Power MOSFETs are still the device of choice for drain-to-source voltages of 1 to 200 V.
The ISFET (ion-sensitive field-effect transistor) can be used to measure ion concentrations in a solution; when the ion concentration (such as H+, see pH electrode) changes, the current through the transistor will change accordingly.
The JFET (junction field-effect transistor) uses a reverse biased p–n junction to separate the gate from the body.
The MESFET (metal–semiconductor field-effect transistor) substitutes the p–n junction of the JFET with a Schottky barrier; and is used in GaAs and other III-V semiconductor materials.
The MODFET (modulation-doped field-effect transistor) uses a quantum well structure formed by graded doping of the active region.
The MOSFET (metal–oxide–semiconductor field-effect transistor) utilizes an insulator (typically SiO2) between the gate and the body.
The NOMFET is a nanoparticle organic memory field-effect transistor.[2]
The OFET (organic field-effect transistor) uses an organic semiconductor in its channel.
The GNRFET (graphene nanoribbon field-effect transistor) uses a graphene nanoribbon for its channel.
The VeSFET (vertical-slit field-effect transistor) is a square-shaped junctionless FET with a narrow slit connecting the source and drain at opposite corners. Two gates occupy the other corners, and control the current through the slit. [3] [4]
The TFET (tunnel field-effect transistor) is based on band-to-band tunneling.[12]
en.wikipedia.org/wiki/Field-effect_transistor