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Memory

The control of electronics

Sixty years ago, Bell Labs introduced the transistor, the cornerstone of the IT revolution

 

Bell Labs Replica of the first transistor: clunky and innovativeBell Labs

Soon after World War II, the US company Bell Telephone Laboratories, or Bell Labs, a firm with a long tradition in basic research into technology, decided to increase its investments in learning more about semiconductors. In 1946, a solid state physics group was created at the firm, bringing together experts from several fields. Physicist William Shockley set up a team to work with semiconductors, believing that the investment in this sector would also advance telecommunications technology substantially. Physicists Walter Brattain and John Bardeen were among those drawn into the project. On July 1, 1948, Bell announced that the three had invented the transistor, an electronic device that controls and amplifies electrical signals and that would become the cornerstone of the entire Information Technology (IT) revolution. “It was the most important invention of the twentieth century,” believes Adalberto Fazzio, from the Physics Institute of the University of São Paulo, who is also the director of the Center for Natural and Human Sciences of the Federal University of ABC and the institution’s acting president.

Naturally, everything did not happen as fast as it now seems. “The Bell labs had been researching semiconductors long before World War II,” said economist Richard Nelson, from Columbia University, in a 1960 essay on the transistor in the book The Sources of Economic Growth (As fontes do crescimento econômico, Editora Unicamp, 2006). Semiconductors are isolating elements, such as germanium and silicon, which conduct electricity when they are enriched with other elements, even though they are not such good conductors as metals like copper. These materials, once warmed, conduct electrical currents more easily than when they are cold, which differentiates them from metals. In 1931, Alan H. Wilson published an article with most of the information needed to understand semiconductors, but this was barely noticed. The concepts were only understood gradually.

ELETRONICS Bardeen and Brattain (standing) and Shockley: shared knowledgeELETRONICS

At Bell Labs, the objectives were clear. The vacuum valve invented by Lee De Forest in 1906 was a major progress, but they knew something better was yet to come. “The valve used a lot of power, didn’t last long, and was expensive and fragile,” says Fazzio. “The idea was to create an amplifier of electrical signals in a solid state; in other words, with semiconductors, as their rectifying properties (only allowing the passage of current in one direction) had been known since the late nineteenth century, having been discovered by Ferdinand Braun, a 1909 Nobel Prize laureate.” Scientists’ motivations were more complex than those of the company. “Their intellectual interests were centered almost exclusively on learning more about semiconductors. Others in the group were concerned with applications as well as with the adjacent scientific disciplines,” wrote Richard Nelson.

A theory developed by John Bardeen in 1947 effectively solved some of the problems and led to the first transistor built by him, Brattain and Shockley in December of 1947, presented in July 1948. The bulk of the work was conducted by the three of them, but Richard Nelson stresses, in his essay, that 13 other people were involved in the research. The name transistor arose because it is a resistor (i.e., it has resistance to electricity) that transfers electrons and amplifies signals. The device, which was 1.5 centimeters when it was created, was later miniaturized and became the heart of integrated circuits and, consequently, of computers.

AMERICAN INSTITUTE OF PHYSICS Bardeen, Cooper and Schrieffer: BCS theoryAMERICAN INSTITUTE OF PHYSICS

Shockley (1910-1989), Brattain (1902-1987) and Bardeen (1908-1991) won the Nobel Prize for Physics in 1956. The following year, Bardeen published articles with Leon Cooper and Robert Schrieffer explaining the superconductivity phenomenon – the capacity of certain materials, at low temperatures, to conduct electricity with no resistance. The theory of superconductivity became known as the BCS theory after them (BCS being the initials of the physicists’ names). “Some of the great twentieth century physicists had already tried, unsuccessfully, to explain this phenomenon, including Niels Bohr, Werner Heisenberg, Wolfgang Pauli and Felix Bloch”, Fazzio tells us. In 1972, Bardeen became the only scientist to win the Nobel Prize twice in the same area.

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