What is MOSFET, its Applications Structure and Working Principle?

What is MOSFET?

The metal-oxide-semiconductor field-effect transistor, also known as the metal-oxide-silicon transistor, It is a type of field-effect transistor that has an insulated gate and is fabricated by the controlled oxidation of a semiconductor,

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BASICS:

The transistor acquires the Gate-Source voltage (VGS) to switch the device “OFF”. The depletion-mode MOSFET is almost to a “normally closed” switch.

Enhance type:

The transistor acquires a Gate-Source voltage (VGS) to switch the device “ON”.

APPLICATION:

1)It is used as an inverter.

2)It can be used in digital circuits.

3)It can be used as passive elements (resistor, inductor & capacitor).

4) It is used in switched-mode power supply (SMPS).

 

MOSFET STRUCTURE:

It is a four-terminal device with source (S), gate (G), drain (D) and Body (B) terminals. The body is often connected to the source terminal, reducing the terminals to three. It works by varying the width of a channel along which charge carriers (electrons or holes).

The charge carriers enter the channel at a source point and exit through the drain. The width of the MOSFET channel is controlled by the voltage that supplies on an electrode is called a gate. It is located between source and drain.

It is insulated from the channel through an extremely thin layer of metal oxide.

WORKING PRINCIPLE:

The goal of MOSFET is to be able to control the voltage and current flow between the source and the drain. It works almost like a switch. The work of MOSFET depends on the MOS capacitor.

The semiconductor surface on the lower oxide layer located between the original and the drainage terminal. It can be converted from p-type to n-type, by applying negative or positive gate voltages respectively.

What is the MOSFET: Basics, Working Principle and Applications

When applying a positive voltage of the gate holes present under a layer of oxide with a repulsive force, and the holes are pushed down with the substrate. An area of exhaustion inhabited by associated negative charges.

That is associated with the reception of atoms. Electrons reach the channel formed. Positive voltage also attracts electrons from the n source and drainage areas into the canal. Now, if the voltage is applied between the drain and the source, the current flow free between the source and the drainage and voltage of the gate control the electrons in the channel. Instead of a positive voltage, if you apply a negative voltage, a hole is formed under the layer of oxide.

The drain and source are heavily doped p-type region and the substrate is an N-type region. The current flows due to the flow of positively charged holes are known as P-channel MOSFET. When we apply negative gate voltage, then the electrons present beneath the oxide layer experience repulsive force and they are pushed downward into the substrate, so the depletion region is filled by the positive charges that bound with the donor atoms.

The negative gate voltage to attract holes from the p-type source and drain region into the channel region. The drain and source are the heavily doped n-type region and the substrate is a p-type region. The current flows due to the flow of negatively charged electrons, be known as N-channel MOSFET. When we apply the positive gate voltage. The holes present beneath the oxide layer experience repulsive force. So the holes are pushed downwards into the bound negative charges. That is associated with the acceptor atoms.

The positive gate voltage and attracts electrons from the n-side are a positive source.because the drain region into the channel thus an electron reach channel is formed.

 

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