Diode
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A Gunn diode is a form of diode that exhibits negative resistance. It consists of a single piece of N-type semiconductor like gallium arsenide. When a voltage is applied, electrons are transferred into a third empty band, increasing their effective mass and decreasing their velocity. This creates a region of negative incremental resistance, where an increase in voltage causes resistance to increase. Gunn diodes are used as oscillators in radar, communications, and as sensors for intruder detection and measuring vibrations or rotational speed.
Diode
- 2. Applications Of Diode GUNN DIODE Maryam Niazi
- 4. INTRODUCTION • A Gunn diode, also known as a transferred electron device (TED), is a form of diode, a two- terminal passive semiconductor electronic component, with negative resistance, used in high-frequency electronics. It is based on the "Gunn effect" discovered in 1962 by physicist J. B.
- 5. What is a Gunn Diode? • A Gunn Diode is considered as a type of diode even though it does not contain any typical PN diode junction like the other diodes, but it consists of two electrodes. • This diode is also called as a Transferred Electronic Device. • It consists of only N-type semiconductor in which electrons are the majority charge carriers.
- 6. WORKING • This diode is made of a single piece of N-type semiconductor such as Gallium Arsenide and InP (Indium Phosphide). • These GaAs and some other semiconductor materials consist of three energy bands, and this extra third band is empty at initial stage. • If a voltage is applied to this device, then most of the applied voltage appears across the active region. • The electrons from the conduction band having negligible electrical resistivity are transferred into the third band because these electrons are scattered by the applied voltage.
- 7. • Because of this, an increase in the forward voltage increases the field strength, then the number of electrons reaching the state at which the effective mass increases by decreasing their velocity, and thus, the current will decrease. • Thus, if the field strength is increased, then the drift velocity will decrease; this creates a negative incremental resistance region • . Thus, increase in the voltage will increase the resistance by creating a slice at the cathode and reaches the anode. • But, to maintain a constant voltage, a new slice is created at the cathode. Similarly, if the voltage decreases, then the resistance will decrease by extinguishing any existing slice.
- 8. APPLICATIONS • Used as Gunn oscillators • These Gunn oscillators are used for radio communications, military and commercial radar sources. • Used as sensors for detecting trespassers. • Used as efficient microwave generators
- 9. Cont… • Used for remote vibration detectors and rotational speed measuring tachometers. • Used as a microwave current generator. • Some other applications include door opening sensors, process control devices, barrier operation, pedestrian safety systems, and intruder alarms.