MOSFET: principle of operation and scope

The study of the properties of a material such as a semiconductor made it possible to make revolutionary discoveries. Over time, technologies have appeared that make it possible to manufacture diodes, MOS transistors, thyristors and other elements on an industrial scale. They successfully replaced electronic tubes and allowed to realize the most daring ideas. Semiconductor elements are used in all spheres of our life. They help us to process huge volumes of information, computers, tape recorders, TV sets, etc. are produced on their basis.

Since the invention of the first transistor, and this was in 1948, it's been a long time. There were varieties of this element: a point-like germanium, silicon, field or MOSFET. All of them are widely used in radio electronic equipment. The study of the properties of semiconductors does not stop in our time.

These studies led to the appearance of a device such as a MOSFET. The principle of its operation is based on the fact that under the influence of the electric field (hence another name - field field), the conductivity of the near-surface layer of the semiconductor located on the boundary with the dielectric varies. It is this property that is used in electronic circuits for various purposes. MOSFET has such a structure that allows to reduce the resistance between the drain and the source under the action of the control signal to almost zero.

Its properties are different from the bipolar "competitor". They determine the scope of its application.

• High speed is provided by miniaturization of the crystal itself and its unique properties. This is due to certain difficulties in industrial production. At the present time, crystals with a gate of 0.06 μm are produced.
• A small transient capacitance allows these devices to operate in high-frequency circuits. For example, LSI with their use is successfully used in mobile communications.
• Virtually zero resistance, which has a MOSFET in the open state, allows it to be used as electronic keys. They can work in circuits for generating high-frequency signals or for shunting elements such as operational amplifiers.
• Powerful instruments of this kind are successfully used in power modules and can enter into induction circuits. A good example of their use can be a frequency converter.

When designing and working with such elements, it is necessary to take into account some features. MOSFETs are sensitive to reverse overvoltage and easily fail. In circuits with inductance, high-speed Schottky diodes are commonly used to smooth out the reverse voltage pulse that occurs when switching.

The prospects for using these devices are quite large. Perfection of the technology of their manufacture goes along the way of crystal reduction (scaling of the shutter). Gradually, there are devices that are able to control more and more powerful electric motors.