Electronics All Types of DIODE

 A diode is a two-terminal device with two active electrodes that permits current to flow in just one way between them. Unidirectional current is a feature of diodes, which allows electric current to flow in just one direction. Diodes are used to correct waveforms and can be found in power supply and radio detectors. They can also be utilized in circuits that need the diode's "one-way" effect. The majority of diodes are constructed of semiconductors like silicon. However, germanium is occasionally utilized. Electric currents flow in just one direction through diodes. The way in which they do it, however, might differ. Diodes come in a variety of shapes and sizes, which can be used in electrical design. The following are examples of the various types:

Light Emitting Diode (LED): 

It is one of the most popular types 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 (electroencephalogram). The color of the light depends on the energy gap of the semiconductor.

Avalanche Diode: 

This type of diode operates in the reverse bias and used the 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 the 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 limited life.

Schottky Diodes: 

These diodes feature lower forward voltage drop as compared to the ordinary silicon PN junction diodes. The voltage drops maybe somewhere between 0.15 and 0.4 volts at low currents, as compared to the 0.6 volts for a silicon diode. In order to achieve this performance, these diodes are constructed differently from normal diodes, with metal to semiconductor contact. Schottky diodes are used in RF applications, rectifier applications, and clamping diodes.

Zener diode: 

This type of diode provides a stable reference voltage, this is a very useful type and is used in vast quantities. The diode runs in reverse bias and breaks down on the arrival of a certain voltage. A stable voltage is produced, if the current through the resistor is limited. In power supplies, these diodes are widely used to provide a reference voltage.

Photodiode: 

Photodiodes are used to detect light and feature wide, transparent junctions. Generally, these diodes operate in reverse bias, wherein even small amounts of current flow, resulting from the light, can be detected with ease. Photodiodes can also be used to generate electricity, used as solar cells, and even in photometry.

Varicap Diode or Varactor Diode:

This type of diode features a reverse bias placed upon it, which varies the width of the depletion layer as per the voltage placed across the diode. This diode acts as a capacitor and capacitor plates are formed by the extent of conduction regions and the depletion region as the insulating dielectric. By altering the bias on the diode, the width of the depletion region changes, thereby varying the capacitance. 

Rectifier Diode:

These diodes are used to rectify alternating power inputs in power supplies. They can rectify current levels that range from an amp upwards. If low voltage drops are required, then Schottky diodes can be used, however, generally, these diodes are PN junction diodes.

Small signal or Small current diode:

These diodes assume that the operating point is not affected because the signal is small

Large signal diodes:

The operating point in these diodes gets affected as the signal is large.

Transient voltage suppression diodes:

This diode is used to protect the electronics that are sensitive against voltage spikes.

Gold doped diodes:

These diodes use gold as the dopant and can operate at signal frequencies even if the forward voltage drop increases. 

Super barrier diodes:

These are also called rectifier diodes. These diodes have the property of low reverse leakage current as that of normal p-n junction diode and low forward voltage drop as that of Schottky diode with surge handling ability.

Point contact diodes:

The construction of this diode is simpler and is used in analog applications and as a detector in radio receivers. This diode is built of n-type semiconductors and a few conducting metals placed to be in contact with the semiconductor. Some metals move from towards the semiconductor to form a small region of p-type semiconductor near the contact.

Peltier diodes:

This diode is used as a heat engine and a sensor for thermoelectric cooling.

 Gunn diode:

This diode is made of materials like GaAs or InP that exhibit a negative differential resistance region.

 Crystal diode:

These are a type of point contact diode which are also called Cat’s whisker diode. This diode comprises a thin sharpened metal wire which is pressed against the semiconducting crystal. The metal wire is the anode and the semiconducting crystal is the cathode. These diodes are obsolete.  

 Avalanche diode:

This diode conducts in reverse bias condition where the reverse bias voltage applied across the p-n junction creates a wave of ionization leading to the flow of a large current. These diodes are designed to break down at specific reverse voltage in order to avoid any damage.  

Silicon controlled rectifier:

As the name implies this diode can be controlled or triggered to the ON condition due to the application of small voltage. They belong to the family of Thyristors and are used in various fields of DC motor control, generator field regulation, lighting system control, and variable frequency drive. These are three-terminal devices with the anode, cathode, and third controlled lead or gate.

Vacuum diodes:

This diode is a two-electrode vacuum tube that can tolerate high inverse voltages.

TYPE OF DIODE

Diodes are used widely in the electronics industry, right from electronics design to production, to repair. Besides the above-mentioned types of diodes, the other diodes are PIN diode, point contact diode, signal diode, step recovery diode, tunnel diode, and gold doped diodes. The type of diode to transfer electric current depends on the type and amount of transmission, as well as on specific applications.