Impatt_and_Trapatt_diodes - Impatt and Trapatt diodes...

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Impatt and Trapatt diodes Impatt is an acronym based on the mechanism of its operation and is derivedfrom Impact Avalanche and Transit Time. Trapatt is derived from Trapped Plasma Avalanche and Triggered Transit. They are both junction diodes which are operated under reverse-bias so that avalanche breakdown occurs. Their structure is similar but there are differences in operation. The Impatt diode p+ n n + The single-drift impatt diode The simplest form of impatt diode is the single-drift diode. As the reverse-bias voltage is increased, the electric field sweeps the region between p+ and n+ clear of carriers to form a depletion layer. At the p+ n interface the high electric field causes avalanche breakdown and electron-hole pairs are formed at the junction. The holes enter the p+ region where their effect can be ignored. The electrons accumulate near the junction until the resultant electric field falls enough to cut off the avalanche. The electrons enter the depletion layer where the electric field is much less than the avalanche field and drifts across the n-region at its saturated constant velocity (about 10 5 ms -1 for silicon when E > 500 V/mm).
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When the bunch of electrons leaves the region, the diode is again ready to
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Impatt_and_Trapatt_diodes - Impatt and Trapatt diodes...

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