Editing High-electron-mobility transistor (section)

{{redirect|HEMT|the military truck|Heavy Expanded Mobility Tactical Truck}}
{{Short description|Type of field-effect transistor}}
[[File:HEMT-scheme-en.svg|350px|thumbnail|Cross section of a GaAs/AlGaAs/InGaAs pHEMT]]
[[File:HEMT-band structure scheme-en.svg|thumb|350px|[[Band diagram]] of GaAs/AlGaAs [[heterojunction]]-based HEMT, at equilibrium.]]

A '''high-electron-mobility transistor''' ('''HEMT''' or '''HEM FET'''), also known as '''heterostructure FET''' ('''HFET''') or '''modulation-doped FET''' ('''MODFET'''), is a [[field-effect transistor]] incorporating a junction between two materials with different [[band gap]]s (i.e. a [[heterojunction]]) as the channel instead of a doped region (as is generally the case for a [[MOSFET]]). A commonly used material combination is [[Gallium arsenide|GaAs]] with [[Aluminium gallium arsenide|AlGaAs]], though there is wide variation, dependent on the application of the device. Devices incorporating more [[indium]] generally show better high-frequency performance, while in recent years, [[gallium nitride]] HEMTs have attracted attention due to their high-power performance.

Like other [[FET]]s, HEMTs can be used in [[integrated circuits]] as digital on-off switches. FETs can also be used as amplifiers for large amounts of current using a small voltage as a control signal. Both of these uses are made possible by the FET’s unique [[current–voltage characteristic]]s. HEMT transistors are able to operate at higher frequencies than ordinary transistors, up to [[millimeter wave]] frequencies, and are used in high-frequency products such as [[cell phone]]s, [[satellite television]] receivers, [[voltage converter]]s, and [[radar]] equipment. They are widely used in satellite receivers, in low power amplifiers and in the defense industry.