The HEMT: A Superfast Transistor
Article Abstract:
The HEMT (high-electron-mobility transistor) or MODFET (modulation-doped field-effect transistor) transistor is a GaAs-AlGaAs device which switches in about ten picoseconds, generates little heat, and can operate as an amplifier up to sixty gigahertz. Much work is going on with the MODFET as its low power consumption and simple fabrication make it superior to other GaAs and silicon transistors. Some vertical FETs and GaAS heterojunction bipolar transistors may be faster than MODFET, but are more difficult to make. The transistor separates electrons and donors and operates at high speeds, due to the fact that electrons move rapidly in undoped GaAs. The device's high transconductance also contributes to the high switching speed. While initial MODFET applications will be in small-scale integration, more important applications will be in supercomputers at liquid-nitrogen temperatures. Other work is being done in MODFET use in low-noise microwave amplifiers and even power applications. Problems still must be solved before the device is ready for commercial use. Supplied in the article are graphs and tables comparing MODFET and other device performance, a diagram of the device structure, and photographs of a low-noise microwave and a ring oscillator MODFET.
Publication Name: IEEE Spectrum
Subject: Engineering and manufacturing industries
ISSN: 0018-9235
Year: 1984
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Painting life into Sammy
Article Abstract:
New York City-based painter Vincent Desiderio has received wide acclaim for his moving portraits of unusual clarity. Few are aware that Desiderio's paintings are about his critically-ill four-year-old son.
Publication Name: The New York Times Magazine
Subject:
ISSN: 0028-7822
Year: 1995
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Bring back the draft
Article Abstract:
The latest kegerators in the market are tested and their details are discussed.
Publication Name: Wired
Subject: Sociology and social work
ISSN: 1059-1028
Year: 2005
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