2016 May

Different Types of Diodes Explained

May 20, 2016


As we have discussed during our Physics tuition classes, diodes are mostly made from semiconductors like, germanium and silicon. Diodes allow one direction flow of electric current, however, how do so can vary from one type to another. Some various types of diodes include:

Light Emitting Diode

Light emitting diodes, most of the times referred to as LEDs, are the most popular diodes. They have p-n junction that allows electrons transfer between the electrodes and as a result light is produced. Even so, not all Light emitting diodes emit visible light. Some of them emit infrared light, which can’t be detected by the human eye. Such LEDs are applied in remote controls like those in, TVs, DVD players, and so forth. When the diode is forward biased, the holes recombine with the electrons and in the process releases energy in form of light. This implies that electronic excitation leads to photon emission, which sequentially leads to electroluminescence or light emission. Aluminum gallium arsenide or aluminum gallium phosphide are normally the materials used in LED production. The color emitted depends on the applied semiconductor material combination.

Avalanche Diode

Avalanche breakdown is sometimes encountered in slightly doped p-n junctions. Avalanche breakdown is the sudden voltage multiplication across a diode. This abrupt voltage increase frequently destroys the diode. Nevertheless, avalanche diodes, which have breakdown voltages of about 4000 V are made in such a manner that they can break down and allow flow of reverse bias current. Therefore, these diodes are commonly used in circuit protection against transient voltages. They are frequently used alongside Zener diodes.

Zener Diode

This is a type of diode that allows current to flow through only in one direction, but in reverse bias, but only if the voltage surpasses a certain point. This voltage limit is called the Zener voltage and it’s static for Zener diodes having breakdown voltage in the range of 1.8 V to 200 V. Hence, Zener diodes are used in circuit protection against damages. As opposed to avalanche diodes, Zener diodes posses p-n junctions which are heavily-doped and the doping is carried out differently to attain distinct Zener breakdown voltages. These diodes are commonly used in electrical circuits to control the voltage.

Schottky Diode

This is also known as the hot-carrier diode. Schottky diodes have lower forward bias voltage drop compared to the regular silicon p-n junction diodes. This voltage drop can be somewhere between 0.15 and 0.4 V at lower currents, compared to the 0.6 V for a standard silicon diode. This lower voltage drop assists the diode in switching from the conducting state to the non-conducting state in significantly shorter time. Hence, they also help in preventing transistor saturation and they are also common in voltage-clamping applications. To attain this overall performance, Schottky diodes are constructed with a semiconductor to metal contact.

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