![]() ![]() Mimura filed a patent disclosure for a HEMT in August 1979, and then a patent later that year. He conceived the HEMT in Spring 1979, when he read about a modulated-doped heterojunction superlattice developed at Bell Labs in the United States, by Ray Dingle, Arthur Gossard and Horst Störmer who filed a patent in April 1978. The basis for the HEMT was the GaAs (gallium arsenide) MOSFET (metal–oxide–semiconductor field-effect transistor), which Mimura had been researching as an alternative to the standard silicon (Si) MOSFET since 1977. ![]() The invention of the high-electron-mobility transistor (HEMT) is usually attributed to physicist Takashi Mimura (三村 高志), while working at Fujitsu in Japan. They are widely used in satellite receivers, in low power amplifiers and in the defense industry.Īdvantages of HEMTs are that they have high gain, this makes them useful as amplifiers high switching speeds, which are achieved because the main charge carriers in MODFETs are majority carriers, and minority carriers are not significantly involved and extremely low noise values because the current variation in these devices is low compared to other. 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 phones, satellite television receivers, voltage converters, and radar equipment. Both of these uses are made possible by the FET’s unique current–voltage characteristics. FETs can also be used as amplifiers for large amounts of current using a small voltage as a control signal. Like other FETs, HEMTs are used in integrated circuits as digital on-off switches. 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. ![]() A commonly used material combination is GaAs with AlGaAs, though there is wide variation, dependent on the application of the device. a heterojunction) as the channel instead of a doped region (as is generally the case for a MOSFET). Band diagram of GaAs/AlGaAs heterojunction-based HEMT, at equilibrium.Ī high-electron-mobility transistor ( HEMT), 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 gaps (i.e. ![]()
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