Metal Oxide Semiconductor Field Effect transistor

The metal-oxide-semiconductor field-effect transistor (MOSFET) is developed by combining field-effect concept areas with MOS technology.

Conventional planar MOSFET is limited to high power management. For high-powered applications, MOSFET is divided into two-dimensional VMOS or VMOS known as Power MOSFET.

What is Power MOSFET?

Power MOSFET is a three terminal (Gate, Drain and Source), four layers (n + pn – n +), Unipolar (most existing carriers only) semiconductor device.

1. MOSFET is a multi-carry device, and since most carriers do not have the re-integration delays, MOSFET achieves the highest bandwidth and switch times.
2. The gate is electrically separated from the source, and while this provides MOSFET with high input impedance, and creates a good capacitor.
   MOSFETs do not have a second breakage location, their resistance to the source of the resistance has a positive temperature coefficient, so they tend to protect themselves.
3. It has very low ON resistance and no junction in the jungle when leaning forward. These features make MOSFET a very attractive power switch.

MOSFET Symbol:

The symbol for n-channel MOSFET is given below. The direction of the arrow on the lead that goes to the body region indicates the direction of current flow. As this is the symbol for n channel MOSFET, the arrow is inwards. For p-channel MOSFET, the arrow will be towards outside.

MOSFET Structure

1. Power MOSFET has a four-layered vertical layout of P and N (n + pn – n +) alternating layers.
2. The middle layer of the P type is called the MOSFET body. In this region, a channel is formed between the well and the water supply.
3. The n-layer is called the drift region, which determines the voltage separation of the device. This n-region is only found in MOSFET Power that is not at MOSFET signal level.
4. The terminal gate is separated from the body by a silicon dioxide layer.
5. When a positive gate voltage is used relative to a well, a n-type channel is formed in the center of the suction source.
6. As shown in the figure, there is a parasitic npn BJT between the source and the water discharge.
7. To prevent the BJT from opening up, the p body region is shortened to become the source area by skipping the source metallization in the p-type body.
8. The result is a parasitic diode formed between the drain to the source terminals. This critical diode plays an important role in partial and complete bridge conversion circuits.

MOSFET VI Characteristics