The history of the invention of the transistor

How do transistors work? The inventor himself didn't know... It's really no joke. In the past two days, IEEE Spectrum published an article about the birth of transistors, which disclosed that scientists only realized the directional conduction effect of the circuit, and announced the results to the public. Even ten years later, relevant contributors have won the Nobel Prize in Physics, and researchers in the circle still say:

Due to the three-dimensional nature of the device, theoretical analysis of its interior remains difficult.

The two subordinates applied for patents without their leader. The latter, with anger and jealousy, invented a new structure in just a few months, replacing the former's achievements and leading the development of transistors for the next 30 years.

What is this past? How does it affect our current life?

Point Contact Transistor to BJT

Before the birth of the transistor, electron tubes (also known as vacuum tubes) were widely used in electronic equipment. The discovery of its principle began with an experiment in 1880 by Edison, the inventor king. He added an extra electrode to the bulb and sprinkled some foil. He found that when the bulb was energized, the third pole was positively charged, and the foil was not reacted, but when the third pole is negatively charged, the foil will float. This phenomenon was summarized by Owen Richardson:

In a high-temperature vacuum environment, the cathode of the circuit will release electrons to the anode, thereby generating a current, and the reverse will not. Among them, the density of molecules in the vacuum environment is small, and the resistance caused by collisions is much smaller, so electrons are naturally easier to move.

Then in 1904, British scientist John Fleming invented the world's first vacuum diode, also known as an electron tube, based on the above principles. Further, the scientists added a grid between the cathode and the anode, using the charges of the same peer to repel each other, changing the flow of electrons through the grid, which can play a role in amplification. Thus, the triode was born.

After the invention of electronic tubes, they were widely used in radio communications, telephones, broadcasting, television, computers, and other fields. In 1929 alone, the industry scale exceeded 1 billion US dollars. 17,468 electron tubes were used in the first computer ENIAC in human history. Until the 1950s, most electronic equipment still used electron tubes. In addition, if new products were invented to replace them from the perspective of other materials and principles, they would be full of risks and uncertainties. Only a few technical practitioners explored this direction.

Among them, William Shockley of AT&T Bell Laboratories in the United States is familiar, as well as his subordinates John Bardeen (John Bardeen) and Walter Brattain. Their new discovery really started by accident.

In November 1947, Bardeen and Bratton encountered a strange phenomenon in their experiments:

On the germanium semiconductor they used, the electron surface layer appears to block an applied electric field from penetrating the semiconductor and regulating the current flow.

Although they didn't figure out how it worked, by December the two had figured out a way to do it:

Fix two pieces of gold foil with a very small distance on a plastic triangle. This part is connected to a spring, and the bottom is semiconductor germanium. The two pieces of gold foil are used as two electrodes, which are in light contact with the semiconductor material.

Thus, a directional conduction effect similar to that of an electron tube can be achieved.

This is the world's first prototype of a point-contact transistor. Since the operation of transistors depends on the special conduction properties of semiconductor materials, the era of semiconductors has also begun. Although scientists failed to clearly and completely explain the underlying principles at the time, and some textbooks directly ignored the introduction of point-contact transistors, it was indeed the first transistor in history.

Later, researchers gradually uncovered the mystery

Specifically, the transistor is built on a thumb-sized N-type germanium plate with an excess of negatively charged electrons, which is treated to have a thin P layer on top with an excess of positive charge and grounded at the bottom. Among the two electrodes in contact with the germanium plate, one has a positive voltage of no more than 1V, and the other has a negative voltage of 4-40V. When electrified, electrons flow from the negative voltage pole to the positive pole, and the current flows in the opposite direction. Conversely, if a larger positive voltage and a smaller negative voltage are applied, the entire system will not conduct due to the repulsion of the same-sex charges.

Compared with electron tubes, point-contact transistors have the advantages of low energy consumption, no need to consider the dissipation of heating electrodes, and no need for a vacuum environment and the device is not easily damaged during use. Of course, compared to today's chips, it is bulky and crude, giving it a cheap look.

But when Bell Labs disclosed the result on June 30, 1948, it shocked the industry without any suspense. Soon, AT&T's manufacturing division, Western Electric, began mass producing the transistor, which is widely used in telephone routing equipment, circuit oscillators, hearing aids, and television signal receivers.

New inventions were quickly applied to cutting-edge military and computing fields. The first transistorized computer in history was born in 1954, the Tradic, an airborne computing machine of the U.S. Air Force. It uses a large number of touch-type transistors inside, its operating power consumption does not exceed 100w, and its volume does not exceed 1 cubic meter. Compared with ENIAC, which occupies an entire warehouse, it can naturally be called SUPER COMPUTER.

Today we seldom touch the contact transistor, because it was quickly replaced as soon as it was invented. Among them, there is a grievance between the inventors of transistors, Bardeen, Bratton, and their boss, Shockley. Since the two subordinates did not bring their boss Shockley in the patent application for contact transistors, he was dissatisfied and resentful. In less than half a year, he designed a new structure of bipolar junction transistors (BJT ).

The principle of BJT is the same as that of point contact, but the structure is quite different. It has two PN junctions with three poles, emitter, collector and base. Taking the NPN structure transistor as an example, a small voltage is connected between the emitter and the base, and then a large voltage is connected between the base and the collector. The low voltage emitter (E pole) flows to the collector (C pole). In this way, a directional amplifier effect is achieved.

It can be seen from the structure that the BJT transistor has a simple structure and is more stable and reliable. This design quickly replaced the original point-contact transistor and dominated for 30 years, and its simple structure laid the foundation for the birth of integrated circuits. Until the emergence of CMOS (Metal Oxide Field Effect Transistor), it was another story.

The BJT structure looks similar to the JFET field effect tube, and both have three electrodes, but the principles of the two are quite different. A BJT is a bipolar transistor involving majority and minority carrier flow, and a JFET is a tripolar source gate drain and is a unipolar transistor.

Inventors after the birth of the transistor

The invention of the transistor is bound to become a landmark event in human history. The Nobel Prize in 1956 was awarded to the three people mentioned above (William Shockley, John Bardeen, and Walter Bratton)

After the invention of the transistor, Bratton turned to another group at Bell Labs to study transistors based on the surface characteristics of semiconductor materials because of his discord with Shockley (which could also be seen before). In 1967, he left Bell Labs to serve as an adjunct professor at Whitman College, where he wrote numerous articles in solid-state physics.

Bratton's father had been a teacher in a private school in China. Therefore, he was born in Tong'an County, Xiamen City, Fujian Province, China. He returned to the United States with his parents when he was 1 year old.

Bardeen was also unable to work with Shockley, and then went to the University of Illinois at Urbana-Champaign as a professor in the School of Electrical Engineering and the School of Physics, and won the second Nobel Prize in Physics in 1972 for his contribution to the theory of superconductivity.

Of the three, Shockley has gone further and is better known by name. In 1956, he came to the southwestern part of the Bay Area in San Francisco, California, and founded the "Shockley Semiconductor Laboratory" of the same name as himself, determined to bring semiconductors from the era of germanium to the era of silicon.

Eight of his employees later became more legendary figures, including the founders of companies such as Fairchild and Intel. Since then, the legend of Silicon Valley and even the entire IT industry has been opened and continues to this day.