MOSFET Basics

MOSFET is a very popular kind of IG-FET. The full form of MOSFET is the Metal Oxide Semiconductor Field Effect Transistor. The diagram of MOSFET is given below.

In these kinds of devices, the gate terminal is separated from the channel using the insulating layer. This insulating layer is formed from the oxide layer of the semiconductor. The insulating layer of MOSFET is formed from SiO2.

What is MOSFET?

In the world of electronics, you all must have heard the term Transistor in your life at least once. But have you ever thought about what are transistors? How do they work? What are the types of transistors? So today you will get the answer to all such questions. In this article, we will understand about the device MOSFET and its characteristics. But before that let me clear the term transistor.

So a transistor is a type of semiconductor device that is used to maintain and regulate the voltage and current level. It has the functions of a switch and an amplifier. You might be thinking about what is the need to study transistors. This is because it is one of the essential components in most of the electronic devices present today. We cannot imagine this world of technology without transistors.

Table of Content

  • What is MOSFET ?
  • Types of MOSFET
  • Working Principle
  • Construction
  • Characteristics

  • Enhancement Type MOSFET
  • Depletion Type MOSFET
  • Enhancement Type Vs Depletion Type MOSFET
  • Uses of MOSFET
  • Applications of MOSFET

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MOSFET Basics

MOSFET is a very popular kind of IG-FET. The full form of MOSFET is the Metal Oxide Semiconductor Field Effect Transistor. The diagram of MOSFET is given below....

What is MOSFET?

Now MOSFET is also classified into two types:-...

MOSFET Types

Now these enhancement type and depletion type MOSFET is further classified into p-channel and n-channel MOSFET....

Working Principle of MOSFET

MOSFET is a type of transistor in which conductivity depends upon the semiconductor channel across the drain and source terminal. This semiconductor channel may be p-channel or n-channel depending upon the configuration of the MOSFET....

MOSFET Construction

MOSFET is a transistor which is used as switch or amplifier and in many other applications. The basic construction of MOSFET can be explained as below:-...

Characteristics of MOSFET

MOSFETs have majorly two characteristics:-...

Enhancement Type MOSFET

1. Drain characteristics of Enhancement Type MOSFET...

Working of N-channel Enhancement Type MOSFET

In such kind of MOSFET, we have to make gate terminal more +ve, hence +ve charges will accumulate in the gate and will attract -ve charges in the body. Electrons will be drifted towards the surface and the region near the surface will become less p type. +ve charges are pushed down. So above region will become n type and thus a channel is formed....

Working of P-channel Enhancement Type MOSFET

A p-channel enhancement type MOSFET is a type of MOSFET which works by applying +ve voltage to the device. It operates according to the voltage applied to the gate terminal. Hence flow of current occurs between drain and source. Step by step explanation:-...

Working of N- channel Depletion Type MOSFET

In this type of MOSFET, three terminals are present- drain, source and gate. Same as other MOSFETs, it also contains a thin insulating layer made up of gate oxide to avoid direct contact with the metal. Here, channel is present from the beginning. By applying a +ve voltage it creates a depletion region reducing the charge carriers and results in decrement of current. MOSFET is generally ON. Drain and source terminal is made up of n-type semiconductor....

Working of P- channel Depletion Type MOSFET

Like any other MOSFETs, this is also made with three main channels- drain, source and gate. Step by step explanation:-...

Symbols

n-channel E-type...

Depletion Type MOSFET

Drain characteristics : ID V/S VDS for various VGS....

Symbols

N-channel D-type...

Difference Between Enhancement Type and Depletion Type MOSFET

Enhancement Type MOSFET Depletion Type MOSFET 1. By applying external voltage in the channel, if the amount of charge carriers increases, it is known as enhancement type MOSFET. 1. By applying external voltage in the channel, if the amount of charge carriers decreases, it is known as depletion type MOSFET. 2. No channel is present in the beginning. 2. Channel is present from the beginning. 3. There is a threshold voltage. 3. There is no such threshold voltage. 4. It does not produce current in the absence of VGS. 4. It can produce current without any gate voltage....

Uses of MOSFET

Used in digital logic circuits. It is used as Amplifiers They are used in Integrated circuits due to small size. It is also used in Microprocessors Used in Power electronics...

Operating Regions of MOSFET

Cutoff Region: In this region of MOSFET, no current flows as the voltage applied in the MOSFET is less than the threshold voltage resulting in the failure of formation of oxide layer. State is OFF. Saturation Region: In this region of MOSFET, a constant amount of current flows between the drain and source because of the threshold voltage. State of MOSFET is ON in this case. Triode Region: It is known as partially conducting state. It is not fully turned on but there is a channel for current flow. Voltage here is moderate....

Switching characteristics for both N channel and P channel MOSFET in tabular form

MOSFET VGS < 0 VGS = 0 VGS > 0 1. P-channel enhancement type ON OFF OFF 2. N-channel enhancement type OFF OFF ON 3. P-channel depletion type ON ON OFF 3. N-channel depletion type OFF ON ON...

Applications of MOSFET

Amplifiers: MOSFETs are used as an amplifiers in order to amplify weak signals. Switching power supplies: They are used as switches because they can alter power supply efficiently. Digital logic gates: They are used to build logic gates such as NAND, NOR etc. Voltage regulators: They are used as voltage regulators because they can control the amount of voltage. Memory devices: They are used in memory cells....

Advantages of MOSFET

High Switching Speed : It can change its state rapidly from ON and OFF position. Low Power Consumption : Useful for battery operated devices. High input impedance : They use minimum input current. Low noise : They produce low noise and do not cause much disturbance....

Disadvantages of MOSFET

Breakdown: MOSFETS have a very thin layer of gate oxide so on applying high voltage it can cause to breakdown of entire device. Temperature: Some functions of MOSFET are altered because of varying temperatures. Voltage capacity: They have a limited voltage capacity. Expensive: Complex manufacturing of MOSFETS can lead to high cost of overall electronic device....

Conclusion

So in this article, we studied about MOSFETs in brief. Its drain and transfer characteristics and how it plays a pivotal role in making different type of electronic devices. We also saw the working of depletion and enhancement type MOSFETs, its differences and symbols. By referring this article, you can get an overview of MOSFET and rest you can also explore it on the internet as it is a vast topic....

Frequently Asked Questions on MOSFET – FAQs

What is active device?...