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Diagram of a simple circuit with an inductance L and a flyback diode D.The resistor R represents the resistance of the inductor's windings. A flyback diode is any diode connected across an inductor used to eliminate flyback, which is the sudden voltage spike seen across an inductive load when its supply current is suddenly reduced or interrupted.
In semiconductor devices, a backward diode (also called back diode [2]) is a variation on a Zener diode or tunnel diode having a better conduction for small reverse biases (for example –0.1 to –0.6 V) than for forward bias voltages. The reverse current in such a diode is by tunneling, which is also known as the tunnel effect. [3] [4] [5]
English: Band diagram of a backward diode. Energy of an electron is on the vertical axis, position in the device is on the horizontal axis. The backward diode has the unusual property that the so-called reverse bias direction actually has more current flow than the so-called forward bias.
The depletion region formed in the diode is very thin (< 1 μm) and the electric field is consequently very high (about 500 kV/m) even for a small reverse bias voltage of about 5 V, allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material.
In electronics, an avalanche diode is a diode (made from silicon or other semiconductor) that is designed to experience avalanche breakdown at a specified reverse bias voltage. The junction of an avalanche diode is designed to prevent current concentration and resulting hot spots, so that the diode is undamaged by the breakdown.
A normally-bound electron (e.g., in a bond) in a reverse-biased diode may break loose due to a thermal fluctuation or excitation, creating a mobile electron-hole pair . If there is a voltage gradient (electric field) in the semiconductor, then the electron will move towards the positive voltage while the hole will move towards the negative voltage.
Under a high reverse-bias voltage, the p-n junction's depletion region widens which leads to a high-strength electric field across the junction. [2] Sufficiently strong electric fields enable tunneling of electrons across the depletion region of a semiconductor , leading to numerous free charge carriers .
Under zero- or reverse-bias (the "off" state), a PIN diode has a low capacitance. The low capacitance will not pass much of an RF signal. Under a forward bias of 1 mA (the "on" state), a typical PIN diode will have an RF resistance of about 1 ohm, making it a good conductor of RF. Consequently, the PIN diode makes a good RF switch.