Difference between Schottky Diode and PN Junction Diode

Difference between Schottky Diode and PN Junction Diode

What is the difference between Bipolar PN junction diode and Schottky diode?

We already have discussed about the basics of general purpose PN Junction diode and the Schottky diode in our previous posts. It is recommended to read basics of PN semiconductor diodes and the basics of Schottky Diodes...

The difference between the bipolar Junction Diode and Schottky Diode are listed in the following table.

PN Junction  Diode Schottky Diode
Bipolar device ( current conduction will happen due to minority & majority carriers) Unipolar device ( current conduction will happen due to majority carriers only)
Semiconductor – semiconductor junction formation Semiconductor – Metal junction formation
Relatively large forward voltage drop (typically 0.65V) Lower forward voltage drop (typically 0.3V)
Available with higher voltage ratings Maximum reverse voltage rating will be 200V
Comparatively On state loss will be more Low On state Losses
Suitable for low-frequency applications (i.e. 50 Hz to 400 Hz) Suitable for high frequency switching applications (ie, up to 300MHz)
Slow turn on & turn off process (due to the presence of stored charge carriers in the junction. These have the effect of momentarily allowing current to flow in the reverse direction when reverse voltage is applied.) Turn on & turn off faster than pn-junction diodes (depletion layer is not formed near the junction because electrons are the majority carriers on both sides of the junction (ie, in the N-type semiconductor as well as in the metal).

The explanation of the above points are given below:

What is meant by unipolar device and bipolar device?

  • The P-type semiconductor has holes as the majority carriers.
  • The N-type semiconductor has electrons as the majority carriers.
  • If the current conduction though the semiconductor device happens due to both majority and minority carriers then it is called as bipolar conduction.
  • That semiconductor device is called as bipolar device. Ex: BJT
  • If the current conduction through the device happens due to majority carriers only, then it is called unipolar conduction. That device is known as Unipolar device. Ex: Diode, JFET

Why schottky diode is suitable for high frequency applications, Why not bipolar junction diode?

  • The schottky diode consists of a Metal - Semiconductor junction. So the depletion layer is absent here.
  • It leads to faster turn-on and turn-off process.
  • Hence the schottky diode is used in high frequency applications like SMPS.

How the bipolar junction diode and schottky diode differ is structure?

Bipolar junction diode is constructed by combining P-type & N-type semiconductors.
The Schottky diode is constructed by combining Metal with N-type semiconductor.
Schottky_Diode_Structure

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