Introduction to Mosfet Transistor

A metal-oxide-semiconductor FET (MOSFET, MOS-FET, or MOS FET) may be a FET (FET with an insulated gate) where the voltage determines the conductivity of the device. it’s used for switching or amplifying signals. the power to vary conductivity with the quantity of applied voltage is often used for amplifying or switching electronic signals. MOSFETs are now even more common than BJTs (Bipolar Junction Transistors) in digital and analog circuits.

A MOSFET is far and away from the foremost common transistor in digital circuits, as many thousands or many them could also be included during a chip or microprocessor. Since they will be made with either p-type or n-type semiconductors, complementary pairs of MOS transistors are often wont to make switching circuits with very low power consumption, within the sort of CMOS logic.

Different Types of Mosfet Transistor

MOSFETs are three-terminal devices with a Gate, Drain and Source and both P-channel (P-MOS) and N-channel (N-MOS) MOSFETs are available. the most difference this point is that MOSFETs are available in two basic forms:

01. Depletion Type: The transistor requires the Gate-Source voltage, ( VGS ) to modify the device “OFF”. The depletion-mode MOSFET is like a “Normally Closed” switch.

02. Enhancement Type: the transistor requires a Gate-Source voltage, ( VGS ) to modify the device “ON”. The enhancement-mode MOSFET is like a “Normally Open” switch.

How does it Work?

The aim of the MOSFET is to be ready to control the voltage and current flow between the source and drain. It works almost as a switch. The working of MOSFET depends upon the MOS capacitor. The MOS capacitor is that the main part of MOSFET. The semiconductor surface at the below oxide layer which is found between source and drain terminal. It is often inverted from p-type to n-type by applying positive or negative gate voltages respectively. once we apply the positive gate voltage the holes present under the oxide layer with repulsion and holes are pushed downward with the substrate. The depletion region populated by the bound negative charges which are related to the acceptor atoms. The electrons reach channel is made. The positive voltage also attracts electrons from the n+ source and drain regions into the channel. Now, if a voltage is applied between the drain and source, the present flows freely between the source and drain and therefore the gate voltage controls the electrons within the channel. rather than a positive voltage, if we apply a negative voltage, a hole channel is going to be formed under the oxide layer.

P-Channel MOSFET:

The P- channel MOSFET features a P- Channel region between source and drain. it’s a four-terminal device like a gate, drain, source, body. The drain and source are heavily doped p+ region and therefore the body or substrate is n-type. The flow of current is charged holes. once we apply the negative gate voltage, the electrons present under the oxide layer are pushed downward into the substrate with a repulsion. The depletion region populated by the bound positive charges which are related to the donor atoms. The negative gate voltage also attracts holes from the p+ source and drain region into the channel region.

N- Channel MOSFET:

The N-Channel MOSFET has an N- channel region between the source and drains it’s a four-terminal device like a gate, drain, source, body. this sort of MOSFET the drain and source are heavily doped n+ region and therefore the substrate or body is P-type. the present flows thanks to the charged electrons. once we apply the positive gate voltage the holes present under the oxide layer pushed downward into the substrate with a repulsion. The depletion region is populated by the bound negative charges which are related to the acceptor atoms. The electrons reach the channel is made. The positive voltage also attracts electrons from the n+ source and drain regions into the channel. Now, if a voltage is applied between the drain and source the present flows freely between the source and drain and therefore the gate voltage controls the electrons within the channel. rather than positive voltage if we apply negative voltage a hole channel is going to be formed under the oxide layer.