What are the advantages of a Schottky diode over an ordinary PN diode? What are its applications.

Schottky diode

This type of diode uses a metal such as gold, silver, or platinum in one. connection side and doped silicon (typically n-type) on the other side. Because on one side of the junction, there is no metal layer depletion in the Schottky diode. The absence of the depletion layer means there is no charge stored at the junction.

When the Schottky diode is unbiased, the free electrons on the n side are in the smaller orbits than the free electrons on the metal side. This difference in the size of the orbit is called the Schottky barrier, it is about 0.25 V. When the diode is forward biased, the free electrons on the n side can gain enough energy to move in a larger orbit. Therefore, free electrons can cross the junction and enter the metal, producing a large forward current. Because metal has no holes, no charge is stored, and no reverse recovery time.

Hot-Carrier Diode

Schottky diodes are sometimes called heat carrier diodes. When Forward bias increases the energy of electrons on the n side to a higher level than the electrons on the metal side of the junction. This increase in energy inspired a hot carrier for the n-side electron. As soon as when these high-energy electrons cross the junction, they fall into the metal, which has a lower energy conduction band.

High-Speed Turnoff 

The absence of charge storage means that the Schottky diode can switch off faster than a normal diode. In fact, Schottky diodes can easily rectify frequencies 300MHz or higher. Even at the above frequencies, it produces a complete half-wave signal. 

The line looks like a rectangular S that represents the Schottky. This is a way to remember the symbols in a schematic.

Applications

The most important use of Schottky diodes is in digital computers. That the speed of your computer depends on the speed at which the diodes and transistors turn on or off. This is where the Schottky diode comes into play. Due to the lack of charge storage, Schottky diodes have become the backbone of low-power Schottky TTL, a group of widely used digital devices

An last, Since the Schottky diode has a barrier potential of only 0.25 V, You may sometimes see it used in low voltage bridge rectifiers because you subtract only 0.25 V instead of the usual 0.7 V for each diode when using the second approach. In a low voltage supply, this lower diode voltage drop is an advantage.

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