What is a Diode?
In this article of types of diode, lets first start with the very first question. What is a diode? Well, a diode is an electronic component which is widely used around the world in circuit boards. Diodes are made up of Silicon and Germanium. Diode got two terminals across its end and allows current to pass only in one direction.
Diode is a unique conductor which uses semiconductor to pass the electricity. Due to its semiconductor properties we can control the flow of electrons that means the flow of electricity and we can also control the flow of electrons by providing external energy. One terminal of the diode is at higher resistance and the other terminal is at lower resistance.
Diodes are also used in rectifiers to convert the AC into DC. The above shown image is the symbol of diode. In the above image one end is named as Anode which is positive terminal and the second end is named as Cathode which is the negative. The direction of the arrow is the direction in which the current can flow, opposite flow is not possible.
When the voltage on Anode is high comparative to Cathode voltage then the diode is in forward-biased state and it allows the flow of electrons that means current. Similarly, when the voltage on Cathode is high comparative to Anode voltage then the diode is in reverse-biased state and it would not allow the flow of current.
Types of Diodes
Light Emitting Diode(LED)
When an electric current passes through the terminals, it emits energy in the form of light and this whole process is called electroluminescence. In many LEDs we can’t see lights emitted by LEDs because of their different frequencies. LEDs are available in different colors. The colors of the LEDs depends on the energy gap of their particular semiconductor on which they are based.
Zener Diode was first produced by Clarence Zener in 1934. It is a semiconductor device and allows current to flow in both directions but better operates as reverse-bias. In reverse-bias it only conducts when it reaches the breakdown voltage, which is called Zener breakdown.
Zener diode was developed to protect the electronic devices from sudden high voltage spikes. It acts as a voltage regulator.
Schottky Diode
In Schottky Diode the junction is created by contacting the semiconductor material with the metal. That is why the forward voltage drop is decreased to a minimum. N-type silicon is used as semiconductor which acts as an anode and metals like Platinum, Tungsten etc. acts as cathode.
Because of the metal junction, they develop high current conducting capabilities and as a result the switching time is reduced. That is the reason Schottky Diodes are used mostly in switching applications.
The voltage drop is low because of the semiconductor-metal junction, as a result the power loss has been reduced and the performance also increased. The Schottky diodes are mostly used in high frequency rectifier applications.
Avalanche Diode
An avalanche diode is one kind of the semiconductor devices and specially built to work in reverse-bias conditions. At a specific reverse voltage avalanche diode breaks down to prevent the damage to the circuit.
Photodiode
A photodiode is also based on semiconductor functionality and with a P-N junction that converts photons into electrical energy. Photodiodes working is exactly opposite of LEDs, they convert electricity into light. Photodiodes are also known as photo-detector, a light-detector, a photo sensor.
The p-layer has majority of holes and the n-layer has the majority of electrons. Photodiodes can be made from variety of semiconductor materials. Every material has its own benefits like low cost, wave length range, low noise levels, response speed etc.
Photodiodes are used in safety electronics, medical applications, used in solar cell panels, logic circuits, character recognition circuits etc.
Constant Current Diodes
It also know as Current-Limiting Diode, Diode-Connected Transistor or Current-Regulating Diode. These diodes are used there where we need to regulate the voltage at a particular current. The function of a constant current diode is to prevent the circuit to get short circuits. The constant current diode symbol is given below.
Large Signal Diode
PN junction is very large in these diodes. That is the reason they are mostly used in rectification that means converting AC to DC. Due to the large PN junction the forward current carrying capacity and reverse blocking voltage of the diode increases. For the high frequency application these diodes are not suitable.
These diodes are majorly used in power supplies. The value of forward resistance is few Ohms and the value of reverse blocking resistance is in Mega Ohms in these type of diodes.
At the end of this “types of diode” article” try this project.