XIV Международная студенческая научная конференция Студенческий научный форум - 2022

t one time, the creators of the transistor were awarded the Nobel Prize for its discovery. This small device changed humanity forever: from simple radios to processors, in which their number reaches several billion. Transistors perform a wide variety of functions. These are the successors and heirs of radio tubes, the so-called vacuum triodes.

In a scientific way -a transistor, a semiconductor triode, is a radio — electronic component made of a semiconductor material, usually with three pins, capable of controlling significant current in the output circuit from a small input signal, which allows it to be used for amplifying, generating, switching, and converting electrical signals. Currently, the transistor is the basis of the circuitry of the vast majority of electronic devices and integrated circuits.

On December 16, 1947, experimental physicist Walter Brattain, who worked with theorist John Bardeen, assembled the first workable point transistor. Six months later, German physicists Herbert Matare and Heinrich Welker presented a point transistor developed in France. So from unsuccessful attempts to create first a solid-state analogue of a vacuum triode, and then a field-effect transistor, the first imperfect point bipolar transistor was born.In 1956, William Shockley, John Bardeen, and Walter Brattain received the Nobel Prize in Physics for their study of the transistor effect.

Transistors are bipolar and field-effect.The bipolar transistor uses semiconductors with both types of conductivity, it works due to the interaction of two closely located p-n junctions on the crystal and is controlled by the change in current through the base-emitter junction, while the output of the emitter in the "common emitter" circuit is common to the control and output currents. The field-effect transistor uses semiconductors of only one type of conductivity, located in the form of a thin channel, which is affected by the electric field of the gate isolated from the channel, the control is carried out by changing the voltage between the gate and the source. A field-effect transistor, unlike a bipolar transistor, is controlled by voltage, not current.

The main advantages that allowed transistors to replace their predecessors (vacuum tubes) in most electronic devices:

Small size and light weight, which contributes to the development of miniaturization of electronic devices;

A high degree of automation and the group nature of operations at many stages of the manufacturing process, which leads to a constant decrease in the unit cost of mass production;

Low operating voltages, which allows the use of transistors in small-sized and energy-efficient electronic devices powered by small-sized electrochemical current sources;

No additional time is required to warm up the cathode after switching on, which allows you to achieve almost instantaneous readiness for operation of transistor devices immediately after power supply;

Low power dissipation compared to lamps due to the lack of heating of the cathode, which contributes to energy efficiency, facilitates the removal of excess heat and allows you to increase the compactness of the devices;

High reliability and high physical strength, resistance to mechanical shock and vibration, which allows you to avoid problems when using the devices in conditions of any shock and vibration loads;

Very long service life — some transistor devices have been in operation for more than 50 years and have not lost their performance;

The ability to combine multiple elements in a single miniature structural module allows for a significant increase in the degree of integration and facilitates the development of combined circuits of high complexity, which is not possible with vacuum tubes. Low power dissipation compared to lamps, including due to the lack of heating of the cathode, which contributes to energy efficiency, facilitates the removal of excess heat and allows you to increase the compactness of the devices;

Disadvantages of transistors:

Conventional silicon transistors do not work at voltages higher than 1 kV, vacuum tubes can work with voltages several orders of magnitude higher than 1 kV;

The use of transistors in high-power broadcasting and microwave transmitters is often technically and economically impractical: it requires parallel switching on and matching of many relatively low-power amplifiers.

Powerful and heavy-duty generator lamps with air or water-cooled anode, as well as magnetrons, klystrons, traveling wave lamps (LBW) provide the best ratio of frequency characteristics, power and acceptable cost.

Transistors are much more vulnerable than vacuum tubes to the action of strong electromagnetic pulses, which, among other things, are one of the damaging factors of a nuclear explosion;

Sensitivity to radiation and the effects of cosmic radiation.

The transistor is used in:

Amplifying circuits. It works, as a rule, in an amplifying mode. There are experimental designs for fully digital amplifiers based on a DAC consisting of powerful transistors. Transistors in such amplifiers operate in a key mode.

Signal generators. Depending on the type of generator, the transistor can be used either in key mode (generation of square wave signals) or in amplification mode (generation of arbitrary waveforms).

Electronic keys. Transistors operate in a key mode. Key circuits can be conventionally called digital signal amplifiers (regenerators). Sometimes electronic keys are also used to control the current strength in an analog load. This is done when the load has a sufficiently large inertia, and the voltage and current in it are regulated not by the amplitude, but by the pulse width. Household dimmers for incandescent lamps and heating devices, as well as switching power supplies, are based on a similar principle.

Transistors are used as active (amplifying) elements in amplifying and switching stages.

Technological limit for transistors has not been reached yet. Their size is decreasing with every goal and various research institutes are looking for new materials for use as a semiconductor. We can say that these semiconductor devices have not said their last word to the world yet.

Bibliography:

Transistor - New World Encyclopedia

Student Yuva: TRANSISTOR-semi conductor device

How does a transistor work? (physlink.com)

transistor | Definition & Uses | Britannica