What is transistor

A transistor is a semiconductor device used to amplify or switch electrical signals and power. The transistor is one of the basic building blocks of modern electronics.[1] It is composed of semiconductor material, usually with at least three terminals for connection to an electronic circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Some transistors are packaged individually, but many more are found embedded in integrated circuits.

Austro-Hungarian physicist Julius Edgar Lilienfeld proposed the concept of a field-effect transistor in 1926, but it was not possible to actually construct a working device at that time.[2] The first working device to be built was a point-contact transistor invented in 1947 by American physicists John Bardeen and Walter Brattain while working under William Shockley at Bell Labs. The three shared the 1956 Nobel Prize in Physics for their achievement.[3] The most widely used type of transistor is the metal–oxide–semiconductor field-effect transistor (MOSFET), which was invented by Mohamed Atalla and Dawon Kahng at Bell Labs in 1959.[4][5][6] Transistors revolutionized the field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers, among other things.

Most transistors are made from very pure silicon, and some from germanium, but certain other semiconductor materials are sometimes used. A transistor may have only one kind of charge carrier, in a field-effect transistor, or may have two kinds of charge carriers in bipolar junction transistor devices. Compared with the vacuum tube, transistors are generally smaller and require less power to operate. Certain vacuum tubes have advantages over transistors at very high operating frequencies or high operating voltages. Many types of transistors are made to standardized specifications by multiple manufacturers.                                                                                                                                       Important of Transistor.                   

Transistors are the key active components in practically all modern electronics. Many thus consider the transistor to be one of the greatest inventions of the 20th century.[61]

The invention of the first transistor at Bell Labs was named an IEEE Milestone in 2009.[62] The list of IEEE Milestones also includes the inventions of the junction transistor in 1948 and the MOSFET in 1959.[63]

The MOSFET (metal–oxide–semiconductor field-effect transistor), also known as the MOS transistor, is by far the most widely used transistor, used in applications ranging from computers and electronics[49] to communications technology such as smartphones.[64] The MOSFET has been considered to be the most important transistor,[65] possibly the most important invention in electronics,[66] and the birth of modern electronics.[67] The MOS transistor has been the fundamental building block of modern digital electronics since the late 20th century, paving the way for the digital age.[68] The US Patent and Trademark Office calls it a "groundbreaking invention that transformed life and culture around the world".[64] Its importance in today's society rests on its ability to be mass-produced using a highly automated process (semiconductor device fabrication) that achieves astonishingly low per-transistor costs. MOSFETs are the most numerously produced artificial objects ever with more than 13 sextillion manufactured by 2018.[69]

Although several companies each produce over a billion individually packaged (known as discrete) MOS transistors every year,[70] the vast majority of transistors are now produced in integrated circuits (often shortened to IC, microchips or simply chips), along with diodes, resistors, capacitors and other electronic components, to produce complete electronic circuits. A logic gate consists of up to about twenty transistors whereas an advanced microprocessor, as of 2021, can use as many as 39 billion transistors (MOSFETs).[71]

The transistor's low cost, flexibility, and reliability have made it a ubiquitous device. Transistorized mechatronic circuits have replaced electromechanical devices in controlling appliances and machinery. It is often easier and cheaper to use a standard microcontroller and write a computer program to carry out a control function than to design an equivalent mechanical system to control that same function.