History of the transistor facts for kids

A transistor is a tiny electronic switch. It's a semiconductor device with at least three connection points. One point controls the flow of electricity between the other two. This lets it make signals stronger (like in a radio receiver) or turn signals on and off very quickly (like in digital circuits).

Before transistors, devices called vacuum tubes did this job. Vacuum tubes were much bigger and used a lot more power. The first working transistor was shown on December 23, 1947. This happened at Bell Laboratories in New Jersey, USA. William Shockley, John Bardeen, and Walter Brattain are the scientists who invented it. Many people think the transistor is one of the most important inventions ever.

Transistors mainly come in two types: bipolar junction transistors (BJTs) and field-effect transistors (FETs). The idea for a field-effect transistor was first suggested in 1925 by Julius Edgar Lilienfeld. The first working transistor, a point-contact transistor, was made by Bardeen, Brattain, and Shockley in 1947. Shockley later improved it with the bipolar junction transistor in 1948. This led to transistors being used widely in the early 1950s.

The MOSFET (metal–oxide–semiconductor field-effect transistor) was invented by Mohamed Atalla and Dawon Kahng in 1959. MOSFETs use even less power. This made it possible to produce huge numbers of transistors for many different uses. The MOSFET has become the most common electronic device ever made.

How Did the Transistor Idea Begin?

Julius Edgar Lilienfeld, c. 1934

The first idea for a field-effect transistor was patented in 1925. It was by an Austrian-Hungarian physicist named Julius Edgar Lilienfeld. However, Lilienfeld didn't publish much about his work. So, the industry didn't pay attention to it. In 1934, German physicist Dr. Oskar Heil also patented a field-effect transistor. We don't have direct proof these early devices were built. But later work in the 1990s showed that one of Lilienfeld's designs actually worked.

Legal papers from Bell Labs show that William Shockley and Gerald Pearson built working versions of Lilienfeld's designs. Yet, they never mentioned this in their own research papers.

John Bardeen, William Shockley and Walter Brattain at Bell Labs, 1948

Bell Labs started working on transistors during World War II. They were trying to make very pure germanium "crystal" diodes. These were used in radar units. Early electronic circuits using vacuum tubes weren't fast enough for radar. So, the Bell team used solid-state diodes instead.

After the war, Shockley wanted to build a semiconductor device like a triode. He got funding and lab space. He worked on the problem with Bardeen and Brattain. John Bardeen developed a new area of quantum mechanics to explain strange behaviors they saw. Bardeen and Walter Brattain eventually built a working device.

The key was understanding how electron mobility works in a semiconductor. Scientists realized that if they could control the flow of electrons, they could build an amplifier. It was hard to do this at first. But they found that placing contacts very close together on the crystal's surface was important.

Walter Brattain worked on building such a device. They saw hints of amplification, but it was tricky. Sometimes it worked, sometimes it didn't. Once, a broken system started working when put in water! They realized that a very small number of electrons in the right place could make the current flow.

Their understanding helped solve the problem. Instead of two separate semiconductors, a single larger surface could work. The input and output contacts would be close on top. The control contact would be at the base of the crystal. A small current to the "base" would push electrons across the semiconductor. This would allow current to flow between the other two contacts.

A student named Ralph Bray saw similar strange effects at Purdue University. He observed very low resistance when voltage pulses were applied. This was a mystery until 1948. It was the effect of "minority-carrier injection," which Shockley later identified. This effect made the transistor possible.

Shockley's team first tried to build a field-effect transistor (FET). But they had problems with the surface of the materials. While trying to understand why their FET failed, they accidentally invented the bipolar point-contact transistor and junction transistors.

The First Working Transistor

A replica of the first transistor

The Bell team tried many ways to build their device. But setups with contacts close enough were often too fragile. They would only work for a short time, if at all. Then, they had a breakthrough. They glued a piece of gold foil to a plastic wedge. They sliced the foil at the tip with a razor. This made two very close gold contacts.

When the plastic was pressed onto a crystal, and voltage was applied to the other side (the base), current flowed. The base voltage pushed electrons towards the contacts. This was how the point-contact transistor was invented.

Walter Brattain's lab notes from December 15, 1947, show: "When the points were very close together got voltage amp about 2 but not power amp." The next day, December 16, 1947, he noted: "power gain 1.3 voltage gain 15 on a plate bias of about 15 volts."

Brattain and H. R. Moore showed the device to colleagues on December 23, 1947. This date is often called the birth date of the transistor. The "PNP point-contact germanium transistor" worked as a speech amplifier. It had a power gain of 18. In 1956, John Bardeen, Walter Houser Brattain, and William Bradford Shockley won the Nobel Prize in Physics. They were honored for their work on semiconductors and discovering the transistor effect.

About twelve people were directly involved in inventing the transistor at Bell Labs.

At the same time, European scientists were also working on solid-state amplifiers. German physicist Herbert Mataré had done experiments since 1942. He observed similar effects with silicon diodes. On August 13, 1948, Mataré and Heinrich Welker applied for a patent in France. They called their device the "Transistron." It was shown publicly in May 1949. These Transistrons were made for the French telephone company and military. In 1953, a radio with four Transistrons was shown in Germany.

Bell Labs didn't announce their transistor until June 1948. So, the Transistron was an independent invention.

Where Did the Name "Transistor" Come From?

Bell Telephone Laboratories needed a name for their new invention. They thought about names like "Semiconductor Triode" or "Crystal Triode." But "Transistor," suggested by John R. Pierce, was chosen. Engineers at Bell liked names ending in "-istor."

The name "transistor" combines "transconductance" or "transfer" with "varistor". A varistor is a type of resistor. The new device could transfer a signal and also had gain (making the signal stronger). So, the name described what it did.

John R. Pierce remembered it a bit differently. He thought about what the device did. It was like the opposite of a vacuum tube. Vacuum tubes had "transconductance." So, the transistor would have "transresistance." He wanted the name to fit with other devices like "varistor" and "thermistor."

The Nobel Foundation says the term combines "transfer" and "resistor".

Early Disagreements

Shockley was unhappy that Bardeen and Brattain got the credit. He felt they had worked "behind his back." Things got worse when Bell Labs lawyers found that some of Shockley's own writings were similar to Lilienfeld's 1925 patent. They decided it was best to leave Shockley's name off the patent application.

Making Transistors Better

Switching to Silicon

The first transistors used germanium. Germanium was hard to clean and didn't work well in all temperatures. Scientists thought silicon would be easier to use. But few people tried it. Morris Tanenbaum and others at Bell Labs made the first working silicon transistor on January 26, 1954. A few months later, Gordon Teal at Texas Instruments also made one. These early silicon transistors were made by adding impurities to silicon crystals as they grew.

A better method was developed by Morris Tanenbaum and Calvin S. Fuller in 1955. They used gaseous diffusion to add impurities to silicon chips.

However, germanium remained the main material for transistors until the late 1950s. Germanium seemed to work better at first. This was because early silicon devices had problems with their surfaces. This stopped electricity from reliably reaching the silicon layer.

Protecting Silicon Surfaces

In 1955, Carl Frosch and Lincoln Derick at Bell Labs found something by accident. They discovered that silicon dioxide (SiO2) could grow on silicon. This oxide layer could stop certain impurities from entering the silicon. This was called the "passivating effect."

In the 1950s, Mohamed Atalla continued Frosch's work. He studied the surface of silicon. He suggested a new way to make semiconductor devices. It involved coating a silicon wafer with an insulating layer of silicon oxide. This allowed electricity to reliably go through to the silicon below. This method, called surface passivation, became very important. It made it possible to mass-produce silicon integrated circuits. Atalla shared his findings in 1957. His method was the basis for two inventions in 1959: the MOS transistor by Atalla and Dawon Kahng, and the planar process by Jean Hoerni.

The Planar Process

In 1958, Atalla talked about surface passivation at a meeting. He showed how silicon dioxide protected the silicon surface. Jean Hoerni was at the meeting and was very interested. Hoerni then came up with the "planar idea." He realized that transistors could be protected by a layer of silicon dioxide.

Jean Hoerni developed the planar process at Fairchild Semiconductor. He got a patent for it in 1959. This process made it possible to mass-produce single-chip silicon integrated circuits.

The MOSFET

The MOSFET was introduced in 1959. Even in 2020, it is still the most common type of transistor. An estimated 13 quintillion (1.3 x 10^22) MOSFETs were made between 1960 and 2018. The main benefits of MOSFETs are that they use almost no power when not switching. They also switch much faster. This makes them perfect for digital signals.

Early Commercial Uses

The first factory to make transistors was at the Western Electric plant in Allentown, Pennsylvania. Production started on October 1, 1951. They made the point-contact germanium transistor.

The first commercial use of transistors in telecommunication was in 1952. They were used in tone generators for phone switching systems. This was for the first trial of direct distance dialing (DDD).

By 1953, transistors were in some products, like hearing aids. But there were still problems. They were sensitive to moisture and the wires were fragile. Donald G. Fink, a research director, wondered if the transistor was a "pimpled adolescent" with a bright future or if it had already peaked.

Early semiconductor companies focused on junction transistors. But these were bulky and hard to mass-produce. This limited them to special uses.

Transistor Radios

The Regency TR-1 was the world's first commercially produced transistor radio. It used Texas Instruments' NPN transistors.

Early transistor radio prototypes were just lab curiosities. However, in 1950, Shockley developed a new type of amplifier. It was called the bipolar junction transistor. Morgan Sparks made this transistor practical. These were licensed to other companies, like Texas Instruments. Texas Instruments made a few transistor radios to help sell their transistors. Early transistors were not very stable. They only worked for low-power, low-frequency uses. But as designs improved, these problems were solved.

Many companies claim to have made the first practical transistor radio. Texas Instruments showed all-transistor radios in 1952. But they didn't work as well as vacuum tube radios. A working all-transistor radio was shown in August 1953 by the German company Intermetall. It used four of their handmade transistors. But like the early Texas units, only prototypes were built. It was never sold to the public.

The first transistor radio is often wrongly credited to Sony. Sony (then Tokyo Tsushin Kogyo) released the TR-55 in 1955. But the Regency TR-1 came first. It was made by Regency Division of I.D.E.A. in Indiana. The TR-1 was announced on October 18, 1954. It went on sale in November 1954 for $49.95 (about $500 today). About 150,000 units were sold.

The TR-1 used four Texas NPN transistors. It needed a 22.5-volt battery. This was because early transistors needed high voltage for good performance. This made the TR-1 expensive to run. It was more popular as a new, cool item than for its performance.

Still, the TR-1 was very advanced for its time. It used printed circuit boards and tiny parts.

Masaru Ibuka, co-founder of Sony, visited the US. Bell Labs was offering licenses to make junction transistors. Ibuka got special permission to pay the $50,000 license fee. In 1955, Sony released their five-transistor "coatpocket" radio, the TR-55. This was under their new brand name, Sony. This product helped Sony grow into a major manufacturing company.

The TR-55 was similar to the Regency TR-1. It also used a 22.5-volt battery and was not very practical. (Note: The TR-55 actually used a 6-volt supply). Few were sold outside Japan. In 1957, Sony made their important "TR-63" shirt pocket radio. This was a much better design. It ran on a standard 9-volt battery. It could compete well with portable vacuum tube radios. The TR-63 was also the first transistor radio to use all miniature parts. (Sony even made special shirts with big pockets for their salesmen!)

On April 28, 1955, Chrysler and Philco announced the first all-transistor car radio. Chrysler offered the Mopar model 914HR as an option for its 1956 cars. It cost $150.

The Sony TR-63, released in 1957, was the first mass-produced transistor radio. It sold seven million units worldwide by the mid-1960s. Seeing Sony's success, other Japanese companies like Toshiba and Sharp Corporation joined the market. Sony's success with transistor radios led to transistors replacing vacuum tubes as the main electronic technology in the late 1950s.

Hobby Use

The first low-cost transistor for the public was the CK722. It was a small germanium transistor. Raytheon introduced it in early 1953 for $7.60. In the 1950s and 1960s, many electronics projects for hobbyists used the CK722. Raytheon also helped by publishing "Transistor Applications" books.

Transistor Computers

The world's first transistor computer was built at the University of Manchester in November 1953. It was built by Richard Grimsdale. The machine used point-contact transistors. These transistors could have two stable states. However, the computer was hard to develop because the transistors were not reliable. It used 150 watts of power.

Metropolitan Vickers Ltd rebuilt the design in 1956. Their version used 200 junction transistors and 1300 diodes.

The IBM 7070 (1958), IBM 7090 (1959), and CDC 1604 (1960) were the first computers sold that used transistors.

The MOSFET (MOS Transistor)

Mohamed Atalla (right), and Dawon Kahng (partially visible, left) invented the MOSFET in November 1959.

Building on his silicon surface passivation method, Mohamed Atalla developed the metal–oxide–semiconductor (MOS) process. He suggested this process could make the first working silicon field-effect transistor (FET). He started building it with Dawon Kahng at Bell Labs.

MOSFET, showing gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink).

Atalla and Kahng invented the metal–oxide–semiconductor field-effect transistor (MOSFET). They made the device in November 1959. They presented it in early 1960. The MOSFET can be made very small. It uses much less power and can be packed more densely than bipolar junction transistors. This made it possible to build high-density integrated circuits (ICs). These ICs could hold more than 10,000 transistors on one chip.

The first gallium-arsenide Schottky-gate field-effect transistor (MESFET) was made by Carver Mead in 1966. The first report of a floating-gate MOSFET (FGMOS) was by Dawon Kahng and Simon Sze in 1967.

The MOSFET has become the most widely made device in history. By 2018, about 13 sextillion MOS transistors had been manufactured.

PMOS and NMOS

There were two original types of MOSFET logic: PMOS (p-type MOS) and NMOS (n-type MOS). Atalla and Kahng developed both types when they invented the MOSFET. They made both PMOS and NMOS devices.

CMOS

A new type of MOSFET logic, CMOS (complementary MOS), was invented by Chih-Tang Sah and Frank Wanlass. They worked at Fairchild Semiconductor. They published their invention in a research paper in February 1963.

Self-Aligned Gate

The self-aligned gate (silicon-gate) MOSFET transistor was invented by Robert Kerwin, Donald Klein, and John Sarace at Bell Labs in 1967. Researchers Federico Faggin and Tom Klein at Fairchild Semiconductor later used self-aligned gate MOSFETs. They used them to develop the first silicon-gate MOS integrated circuit.

MOSFET in Commercial Products

The MOSFET, also known as the MOS transistor, was the first truly small transistor. It could be made tiny and mass-produced for many uses. It changed the whole electronics industry. This included power electronics, consumer electronics, control systems, and computers. The MOSFET is now the most common type of transistor. It's used in computers, electronics, and communications technology (like smartphones). The MOS transistor is called the "workhorse of the electronics industry." This is because it's the basic part of every microprocessor, memory chip, and telecommunication circuit. Billions of MOS transistors are made every day.

Integrated Circuits

General Microelectronics introduced the first commercial MOS integrated circuits in 1964. These had 120 p-channel transistors. It was a 20-bit shift register. Robert Norman and Frank Wanlass developed it. In 1967, Bell Labs researchers Robert Kerwin, Donald Klein, and John Sarace developed the self-aligned gate (silicon-gate) MOS transistor. Fairchild Semiconductor researchers Federico Faggin and Tom Klein used this to develop the first silicon-gate MOS IC.

By 1972, MOS LSI (large-scale integration) circuits were sold for many uses. These included automobiles, trucks, home appliances, business machines, electronic musical instruments, computer peripherals, cash registers, calculators, data transmission, and telecommunication equipment.

Semiconductor Memory

The first modern memory cells came out in 1965. John Schmidt designed the first 64-bit MOS SRAM (static RAM). In 1967, Robert H. Dennard of IBM patented a single-transistor DRAM (dynamic RAM) memory cell. It used a MOSFET.

The first practical use of floating-gate MOSFET (FGMOS) was in floating-gate memory cells. Dawon Kahng and Simon Sze suggested these could make reprogrammable ROM (read-only memory). Floating-gate memory cells later became the basis for non-volatile memory (NVM) technologies. These include EPROM (erasable programmable ROM), EEPROM (electrically erasable programmable ROM), and flash memory.

Microprocessors

The MOSFET is the basis of every microprocessor. The earliest microprocessors were all MOS microprocessors. They were built with MOS LSI circuits. The first multi-chip microprocessors, the Four-Phase Systems AL1 (1969) and the Garrett AiResearch MP944 (1970), used multiple MOS LSI chips. The first commercial single-chip microprocessor, the Intel 4004, was developed by Federico Faggin. He used his silicon-gate MOS IC technology. He worked with Intel engineers Marcian Hoff and Stan Mazor, and Busicom engineer Masatoshi Shima. When CMOS microprocessors arrived in 1975, "MOS microprocessors" referred to chips made only from PMOS logic or NMOS logic.

Pocket Calculators

One of the first important consumer electronic products made possible by MOS transistors was the electronic pocket calculator. In 1965, the Victor 3900 desktop calculator was the first MOS LSI calculator. It had 29 MOS LSI chips. In 1967, the Texas Instruments Cal-Tech was the first prototype electronic handheld calculator. It had three MOS LSI chips. It was later released as the Canon Pocketronic in 1970. The Sharp QT-8D desktop calculator was the first mass-produced LSI MOS calculator in 1969. The Sharp EL-8, which used four MOS LSI chips, was the first commercial electronic handheld calculator in 1970. The first true electronic pocket calculator was the Busicom LE-120A HANDY LE. It used a single MOS LSI calculator-on-a-chip from Mostek. It was released in 1971.

Personal Computers

In the 1970s, the MOS microprocessor was the basis for home computers, microcomputers (micros), and personal computers (PCs). This led to the start of the personal computer revolution.

Power Electronics

The power MOSFET is the most widely used power device in the world. It has many benefits over bipolar junction transistors in power electronics. Power MOSFETs don't need a constant flow of current to stay on. They switch faster, lose less power when switching, and have lower resistance when on. They are also less likely to overheat. The power MOSFET changed power supplies. It allowed them to work at higher frequencies, be smaller, lighter, and produced in larger numbers.

The power MOSFET was developed in the early 1970s. It is commonly used in power electronics. It allows for low power to control the gate, fast switching, and easy paralleling.

Patents

• , US 1745175 Julius Edgar Lilienfeld: "Method and apparatus for controlling electric current" first filed in Canada on 1925-10-22, describing a field-effect transistor
• , US 1900018 Julius Edgar Lilienfeld: "Device for controlling electric current" filed on 1928-03-28, a thin film field-effect transistor
• , GB 439457 Oskar Heil: "Improvements in or relating to electrical amplifiers and other control arrangements and devices" first filed in Germany on 1934-03-02
• , US 2524035 John Bardeen et al.: "Three-electrode circuit element utilizing semiconductive materials" oldest priority 1948-02-26
• , US 2569347 William Shockley: "Circuit element utilizing semiconductive material" oldest priority 1948-06-26
• , US 3206670 Mohamed Atalla: "Semiconductor devices having dielectric coatings" filed in 1960-08-03, describing a MOSFET
• , US 3102230 Dawon Kahng: "Electric field controlled semiconductor device" filed in 1960-08-03, describing a MOSFET

Books and Literature

• A history of Bell Laboratories and its technological innovations
• The invention of the transistor & the birth of the information age
• Out of the Crystal Maze Chapters from The History of Solid State Physics
• Electronic Genie: THE TANGLED HISTORY OF SILICON
• The INVENTION THAT CHANGED THE WORLD: HOW A SMALL GROUP OF RADAR PIONEERS WON THE SECOND WORLD WAR AND LAUNCHED A TECH

See also

In Spanish: Historia del transistor para niños