This section provides overview, applications, and principles of gunn diodes. Also, please take a look at the list of 7 gunn diode manufacturers and their company rankings.
A Gunn diode is a diode used in microwave oscillators and other devices that utilize the Gunn effect.
N-type gallium arsenide (GaAs) is mainly used, and physicist J.B. Gunn discovered that oscillation occurs in the microwave region when a DC electric field is applied to GaAs and exceeds a certain threshold value. This phenomenon is therefore called the Gunn effect.
Gunn diodes have an area of negative resistance, and this effect is used in microwave oscillators. Negative resistance is a characteristic in which the current decreases as the voltage increases.
The most common use of Gunn diodes is in oscillators in the microwave region using the Gunn effect.
When a Gunn diode is mounted in a cavity or waveguide and a DC voltage is applied, it oscillates with an intrinsic vibration that depends on the crystal's thickness. The structure is relatively simple, but the frequency stability is not as good as other methods, so it is often used for sensors in addition to communications.
Familiar applications include speed guns for baseball and radars for speed enforcement.
The energy band diagram of GaAs crystals used in Gunn diodes has two conduction bands with different bottom energies and wave numbers when a graph of energy versus wavenumber is drawn.
When voltage is applied, an electric current flows and the electrons responsible for this current are those in the conduction band. Normally, electrons are more abundant in the conduction band with lower energy at the bottom, and as the voltage increases, electrons are also present in the conduction band with higher energy.
When a certain voltage is exceeded, electrons from the lower conduction band are transferred to the higher conduction band, decreasing mobility. This phenomenon causes the current to decrease even when the voltage is increased when a certain voltage is exceeded, resulting in the characteristic of negative resistance.
When the voltage is further increased, the electrons in the conduction band at the lower level are transferred to the conduction band at the higher level, and the current increases again. Therefore, Gunn diodes have negative resistance in certain intermediate transition regions.
*Including some distributors, etc.
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