Light emitting diodes.
A diode is an electrical component that allows current to flow in only one direction. An ideal diode conducts with zero resistance in one direction and has infinite resistance in the opposite direction. Diodes are widely used in modern electronics, and there are many different types. Diodes vary both in terms of their application and the physical principles that their operation is based on.
PN Junction
A PN junction is a basic semiconductor device that can be used to make a basic diode. Most diodes use PN junctions. PN junctions are created by doping a piece of silicon with two different atoms that result in one side of the piece of silicon having an excess of electrons (negative, or "N" charge carriers), and the other side having an excess of holes (positive, or "P" charge carriers). This means electrical current can only flow in one direction. Practical PN junction diodes require an activation voltage before they stop current flowing. This activation voltage is typically 0.7 volts.
Zener Diode
A zener diode is a type of semiconductor PN junction diode that prevents current flowing in one direction up to a particular voltage. A zener diode allows current to flow in one direction, but will prevent current flowing in the opposite direction while the applied voltage is less than this voltage. Zener diodes are used extensively in power regulators to ensure that voltages are only supplied above a certain level.
Schottky Diode
Schottky diodes are similar to PN diodes except their turn-on voltage is lower than the usual 0.7 volts, sometimes as low as 0.15 volts. This means the Schottky diode behavior is closer to "ideal" diode behavior. To achieve this effect, Schottky diodes are constructed differently from normal PN diodes, usually combining a metal plate and semiconductor components, rather than being made entirely from semiconductor.
Light-Emitting Diode
A light-emitting diode is a type of semiconductor diode that emits photons when current is flowing through it. Light-emitting diodes behave like normal PN semiconducting diodes apart from their producing light. Light-emitting diodes are widely used as status indicators in electronics, as part of screens and as light sources.
Cat's Whisker
Cat's whisker diodes are a very old type of diode. Cat's whiskers are made of a thin wire placed on a mineral crystal. Cat's whiskers are unreliable by the standards of modern diodes but were used in early radio sets.
Laser Diode
Laser diodes are similar to light-emitting diodes except they produce coherent, or laser, light. Laser diodes are used in many applications that require compact, low-power lasers. Laser diodes are used in CD players, DVD drives, laser pointers,and distance measuring devices.
Photodiode
Photodiodes are used to detect light. They can also be used to generate electricity from light, so they can be used as components in solar panels. Photodiodes otherwise behave similarly to normal PN junction semiconductor diodes.
Tags: current flowing, diodes used, Laser diodes, activation voltage, allows current, allows current flow
