What is the difference between Schottky Diode and PN Junction diode?

What is the difference between Schottky Diode and PN Junction diode?

In the normal rectifier grade PN junction diode, the junction is formed between P type semiconductor to N type semiconductor.
Whereas in Schottky diode the junction is in between N type semiconductor to Metal plate.

  • The schottky barrier diode has electrons as majority carriers on both sides of the junction. So it is a unipolar device.
    Thus there is no depletion layer formed near the junction. It give very less voltage drop across the junction.
    In other words the forward voltage drop (Vf) is less compared to normal PN junction type diodes.
  • In the schottky barrier diode, the current conduction is happening due to movement of electrons only.
    There is no holes movement in the opposite direction. It means, the leakage current is negligible.

As the schottky diode is unipolar device(ie, no holes movement in the opposite direction), it does not have much reverse leakage current( current that flows from cathode to anode during reverse biased condition).
Thus there is less delay will happen during electron-hole recombination.
Hence schottky diode can switch( ON / OFF ) faster than PN junction diode.

  • When the schottky diode is forward biased, conduction electrons in the N layer gets huge energy to cross the junction and enter the metal.
  • Since these electrons plunge into the metal with huge energy, they are generally known as hot carriers.
    Thus the schotty barrier diode is also known as hot carrier diode.

Applications of Schottky diode:

  1. It is used in switching power supplies (SMPS).
  2. As it generates less noise, it will use in sensitive communication receivers like radars.
  3. It is used in clipping and clamping circuits and in computer gating.
  4. It is used in construction of integrated circuits designed for high-speed digital logic applications.

The following table gives us the summary of comparative study between Schottky Diode and normal PN Junction diode

Schottky Diode P-N Junction Diode
Junction is formed between N type semiconductor to Metal plate. Junction is formed between P and N type semiconductors.
It has low forward voltage drop. Compare to schottky diode it has more forward voltage drop.
Reverse recovery time and reverse recovery loss are very very less. The Reverse recovery time and reverse recovery loss are more.
They are used in High frequency applications like SMPS circuit. They can be used in high frequency applications.
It is a unipolar device
ie, Current conduction is happening due to movement of electrons only.
It is a bipolar device.
ie, Current conduction is due to movement of both holes and electrons.

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Are we missed any point?... Please share in the comments....

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3 Responses

  1. Michael Walker says:

    Standard PN diodes conduct far less in a reverse bias condition than Shottkey diodes. Shottkey diodes have a much lower capacitance which is why they're used in SMPS applications, but if you want a blocking diode and can tolerate the larger forward voltage drop, the standard PN diode is the way to go.

  2. rushi says:

    how to calculate the ESR for capacitor? tell mee

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