Schottky Diode

What is Schottky Diode?

The schottky diode is a type of metal – semiconductor junction diode, which is also known as hot-carrier diode, low voltage diode or schottky barrier diode. The schottky diode is formed by the junction of a semiconductor with a metal. Schottky diode offers fast switching action and has a low forward voltage drop. As we are aware that in a PN junction diode, p-type and n-type are joined together to form a PN junction. Whereas, in a Schottky diode metals like platinum or aluminum are used instead of P type semiconductors. 

SymbolV-I CharacteristicsWorkingApplicationsAdvantagesDisadvantagesDifference

The symbol for the Schottky barrier diode is based around the basic diode circuit symbol. The circuit symbol of the Schottky diode is shown in the figure.

Schottky Diode Symbol

The V-I characteristics of Schottky diodes are very much similar to the PN junction diode. Current is the dependent variable while voltage is the independent variable in the Schottky diode. The forward voltage drop of the Schottky diode is low between 0.2 to 0.3 volts.

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• The operation relies on the principle that the electrons in different materials have different potential energy.
• N-type semiconductors have higher potential energy than electrons of metals.

• When these two are brought into contact, there is a flow of electrons in both directions across the metal-semiconductor interface.
• A voltage is applied to the Schottky so that the metal is positive when compared to the semiconductor.
• The voltage opposes the built-in potential and makes the current flow easy.

Schottky diodes have been useful for the industry of electronics that has spotted many applications in diode rectifiers because of its unique properties. Here are some major areas where it is widely used.

RF mixer and detector diode:

The Schottky diode consists of its radio frequency functions owing to its switching speed at the highest level and top frequency capability. The Schottky barrier diodes come handy for diode ring mixers with high performance.

Power rectifier:

The Schottky barrier diodes also have functions with high power as rectifiers. The high density of current and voltage drop with low forward shows that the wastage of power is lesser than the normal PN junction diodes.

Power OR circuits:

This diode would be useful for functions where two different power supplies drive a load like in battery supply. It is important that the power coming from supply should not mix with the others.

Solar Cell Applications:

As we know,  the solar cells are usually linked to the batteries that are rechargeable, mostly batteries with lead-acid since power supply must be necessary round the clock. Solar cells would not support the applied charge in reverse and thus, a diode would be used in a proportional pattern of the solar cells.

Following are the advantages of Schottky diode:

• The capacitance of the diode is low as the depletion region of the diode is negligible.
• The reverse recovery time of the diode is very fast, that is the change from ON to OFF state is fast.
• The current density of the diode is high as the depletion region is negligible.
• The turn-on voltage of the diode is 0.2 to 0.3 volts, which is very low.

The only disadvantage of Schottky diodes is that the reverse saturation current of the diode is large.