The element base of semiconductor elements is constantly growing. Each new invention in this area, in fact, changes the whole idea of electronic systems. Circuit design capabilities are changing, new devices based on them are emerging. A lot of time has passed since the invention of the first transistor (1948). The "p-n-p" and "n-p-n" structures, bipolar transistors, were invented. Over time, the MIS transistor also appeared, operating on the principle of changing the electrical conductivity of the near-surface semiconductor layer under the action of an electric field. Hence, another name for this element is field.
The very abbreviation MIS (metal-dielectric-semiconductor) characterizes the internal structure of this device. Indeed, its gate is isolated from the drain and source by a thin non-conductive layer. A modern MIS transistor has a gate length of 0.6 µm. Only an electromagnetic field can pass through it - this is what affects the electrical state of the semiconductor.
Let's look at how a FET works and find out what is its main difference frombipolar "brother". When the required potential appears, an electromagnetic field appears on its gate. It affects the resistance of the drain-source junction. Here are some of the benefits of using this appliance.
- In the open state, the drain-source transition resistance is very small, and the MIS transistor is successfully used as an electronic key. For example, it can drive an operational amplifier by shunting a load or participate in logic circuits.
- Also noteworthy is the high input impedance of the device. This parameter is quite relevant when working in low-current circuits.
- The low capacitance of the drain-source junction makes it possible to use the MIS transistor in high-frequency devices. There is no distortion in signal transmission during the process.
- The development of new technologies in the production of elements has led to the creation of IGBT transistors that combine the positive qualities of field and bipolar elements. Power modules based on them are widely used in soft starters and frequency converters.
When designing and working with these elements, it must be taken into account that MIS transistors are very sensitive to overvoltage in the circuit and static electricity. That is, the device may fail when touching the control terminals. When installing or dismantling, use special grounding.
Prospects for using this device are very good. Thanks toits unique properties, it has found wide application in various electronic equipment. An innovative direction in modern electronics is the use of power IGBT modules for operation in various circuits, including induction circuits.
The technology of their production is constantly being improved. Developments are underway to scale (reduce) the length of the shutter. This will improve the already good performance of the device.
