Device Structure
The IMPATT diode family includes many different junctions and metal semiconductor devices. The first IMPATT oscillation was obtained from a simple silicon p-n junction diode biased into a reverse avalanche break down and mounted in a microwave cavity. Because of the strong dependence of the ionization coefficient on the electric field, most of the electron–hole pairs are generated in the high field region. The generated electron immediately moves into the N region, while the generated holes drift across the P region. The time required for the hole to reach the contact constitutes the transit time delay.
The original proposal for a microwave device of the IMPATT type was made by Read and involved a structure. The Read diode consists of two regions (i) The Avalanche region (a region with relatively high doping and high field) in which avalanche multiplication occurs and (ii) the drift region (a region with essentially intrinsic doping and constant field) in which the generated holes drift towards the contact. A similar device can be built with the configuration in which electrons generated from the avalanche multiplication drift through the intrinsic region.
An IMPATT diode generally is mounted in a microwave package. The diode is mounted with its high–field region close to a copper heatsink so that the heat generated at the diode junction can be readily dissipated. Similar microwave packages are used to house other microwave devices.
Read more about this topic: IMPATT Diode
Famous quotes containing the words device and/or structure:
“One good reason for the popularity of “reductionism” among the philosophical outposts of the Western Establishment is that it can be, and is, used as a device for trying to take the wind, so to speak, out of the sails of Marxism.... In essence reductionism is a kind of anti-Marxist caricature of Marxist determinism. It is what anti-Marxists pretend that Marxist determinism is.”
—Claud Cockburn (1904–1981)
“The verbal poetical texture of Shakespeare is the greatest the world has known, and is immensely superior to the structure of his plays as plays. With Shakespeare it is the metaphor that is the thing, not the play.”
—Vladimir Nabokov (1899–1977)