Diode

A diode is a two-terminal device, having two active electrodes, between which it allows the transfer of current in one direction only. Diodes are known for their unidirectional current property, wherein, the electric current is allowed to flow in one direction. Basically, diodes are used for the purpose of rectifying waveforms, and can be used within power supplies or within radio detectors. They can also be used in circuits where 'one way' effect of diode is required. Most diodes are made from semiconductors such as silicon, however, germanium is also used sometimes. Diodes transmit electric currents in one direction, however, the manner in which they do so can vary. Several types of diodes are available for use in electronics design. Some of the different types are:

Light Emitting Diode (LED): It is one of the most popular type of diodes and when this diode permits the transfer of electric current between the electrodes, light is produced. In most of the diodes, the light (infrared) cannot be seen as they are at frequencies that do not permit visibility. When the diode is switched on or forward biased, the electrons recombine with the holes and release energy in the form of light (electroluminescence). The color of light depends on the energy gap of the semiconductor.

Avalanche Diode: This type of diode operates in the reverse bias, and used avalanche effect for its operation. The avalanche breakdown takes place across the entire PN junction, when the voltage drop is constant and is independent of current. Generally, the avalanche diode is used for photo-detection, wherein high levels of sensitivity can be obtained by the avalanche process.

Laser Diode: This type of diode is different from the LED type, as it produces coherent light. These diodes find their application in DVD and CD drives, laser pointers, etc. Laser diodes are more expensive than LEDs. However, they are cheaper than other forms of laser generators. Moreover, these laser diodes have