What is Schottky Diode ,Application and Comparison with PN junction diodes(A short notes on Schottky Diode )

 Definition

A Schottky Diode is a semiconductor diode formed by the junction of a metal and a semiconductor. It is also known as a hot-carrier diode or low-voltage diode because it uses *hottky barrier to control the flow of electric current. Unlike conventional diodes, which have a P-N junction, Schottky diodes have a metal-semiconductor junction

Symbol of Schottky diode:

Circuit diagram :

Evolution

The Schottky diode was invented by Walter H. Schottky in 1938. It was developed as an alternative to the PN junction diode, which was the only type of diode available at the time. PN junction diodes have a higher forward voltage drop than Schottky diodes, which makes them less efficient in some applications.

Effects

The main effect of a Schottky diode is that it has a low forward voltage drop. This is because the metal-semiconductor junction has a smaller barrier potential than the PN junction. The low forward voltage drop makes Schottky diodes ideal for high-frequency applications, where the switching losses can be significant.

Examples

Some examples of Schottky diodes include:

Gold-silicon Schottky diode

Platinum-silicon Schottky diode

Molybdenum-silicon Schottky diode

Tungsten-silicon Schottky diode

Types

There are two main types of Schottky diodes:

Point-contact Schottky diodes: These diodes are formed by the contact of a metal wire with a semiconductor surface.

Metal-semiconductor junction diodes: These diodes are formed by the deposition of a metal layer on a semiconductor surface.

Working

A Schottky diode works by thermionic emission. When a positive voltage is applied to the diode, electrons from the metal are emitted into the semiconductor. These electrons then flow through the semiconductor, creating a current.

Properties

Schottky diodes have the following properties:

Low forward voltage drop

Fast switching speed

High reverse current

Low noise

High temperature stability

Characteristics

The characteristic curve of a Schottky diode is similar to that of a PN junction diode. However, the forward voltage drop of a Schottky diode is much lower.

Applications

Schottky diodes are used in a variety of applications, including:

High-frequency switching circuits

Rectifiers

Voltage regulators

Low-noise amplifiers

Temperature sensors

Advantages and Disadvantages

The advantages of Schottky diodes include:

Low forward voltage drop

Fast switching speed

Low noise

High temperature stability

The disadvantages of Schottky diodes include:

High reverse current

Not as rugged as PN junction diodes

Comparison with PN junction diodes

The main difference between Schottky diodes and PN junction diodes is the way they are constructed. Schottky diodes have a metal-semiconductor junction, while PN junction diodes have a p-type and n-type semiconductor junction. This difference in construction leads to the following differences in properties and characteristics:

Schottky diodes have a lower forward voltage drop than PN junction diodes.

Schottky diodes have a faster switching speed than PN junction diodes.

Schottky diodes have a higher reverse current than PN junction diodes.

Schottky diodes are not as rugged as PN junction diodes.

Conclusion

Schottky diodes are a type of semiconductor diode that has a low forward voltage drop and a fast switching speed. They are used in a variety of applications, including high-frequency switching circuits, rectifiers, voltage regulators, low-noise amplifiers, and temperature sensors.

FAQs

1. What is the difference between a Schottky diode and a PN junction diode?

The main difference between a Schottky diode and a PN junction diode is the way they are constructed. A Schottky diode has a metal-semiconductor junction, while a PN junction diode has a p-type and n-type semiconductor junction. This difference in construction leads to the following differences in properties and characteristics:

Schottky diodes have a lower forward voltage drop than PN junction diodes.

Schottky diodes have a faster switching speed than PN junction diodes.

Schottky diodes have a higher reverse current than PN junction diodes.

Schottky diodes are not as rugged as PN junction diodes.

2. Why are Schottky diodes used in high-frequency applications?

Schottky diodes are used in high-frequency applications because they have a low forward voltage drop. This low forward voltage drop minimizes the switching losses in high-frequency circuits.

3. What are the disadvantages of Schottky diodes?

The main disadvantages of Schottky diodes are:

They have a higher reverse current than PN

Note : 1 * A Schottky barrier, also known as a Schottky contact or Schottky junction, is a type of electrical junction formed between a metal and a semiconductor material. Unlike a traditional P-N junction in a semiconductor diode, which consists of two semiconductor regions with different doping types (P and N), the Schottky barrier forms at the interface between a metal and a semiconductor.

The Schottky barrier is characterised by the following key features:

1. Rectifying Behaviour

2. Lower Forward Voltage Drop

3. Fast Switching Speed

4. Low Reverse Recovery Time

The formation of the Schottky barrier occurs when a metal, such as aluminum or platinum, contacts a semiconductor material, typically silicon or germanium. The metal's electrons transfer to the conduction band of the semiconductor, creating the barrier and facilitating rectification behavior.

Overall, Schottky barriers play a crucial role in the operation of Schottky diodes, contributing to their unique electrical characteristics and making them valuable components in various electronic circuits and applications