Invention of the Transistor 1947
The invention of the transistor was the sequence of experiments at Bell Labs in Murray Hill, New Jersey, that ended in December 1947 with the first demonstration of amplification in a solid piece of semiconductor, a device later called the point-contact transistor. It was the work of a semiconductor research group formed after the Second World War, with John Bardeen and Walter Brattain making the decisive breakthrough while William Shockley led the group. The story is useful because it shows how a product came out of a research program: a failed idea, a theory that explained the failure, careful experiments, and a demonstration staged for the people who could fund the next step.
The group began with an idea that did not work. In 1945 Shockley proposed a field-effect device, in which an electric field from a nearby plate would draw charge into a thin semiconductor layer and change its conductivity, so that a small signal on the plate would control a larger current. Calculations suggested a measurable effect, yet experiments showed almost none. Bardeen, a theorist who had joined the group in 1945, explained the failure in 1946: electrons were trapped in states at the semiconductor surface, and these surface states screened the interior from the applied field. The field effect was not wrong in principle, only blocked by surface physics, and that diagnosis redirected the whole program toward understanding surfaces.
Brattain's experiments turned the surface-state theory into working hardware. Working with Bardeen, and with the physical chemist Robert Gibney and others, Brattain studied how germanium and silicon surfaces behaved when covered with liquids or probed with contacts, and in November 1947 the group saw signs of amplification from field-effect arrangements. These early arrangements led to a new design: two closely spaced metal contacts pressed onto the surface of a slab of germanium, one acting as an input and one as an output. Closely spaced gold contacts were made by wrapping gold foil around a plastic wedge and slitting it at the tip, a clever way to get two points separated by a tiny gap.
The first amplification came in mid-December 1947 and the formal demonstration a week later. On 15-16 December 1947 the gold-contact germanium device amplified an electrical signal, and Brattain and Bardeen recorded it in their notebooks. On 23 December 1947 they demonstrated it to Bell Labs management, a date usually given as the birth of the transistor. The device was a point-contact transistor: a power gain came from current injected at one contact controlling current collected at the other, through a thin region near the surface of the crystal. It was fragile, noisy and hard to reproduce, but it proved that a solid could do what a vacuum tube did.
The public announcement came the following summer, and the name arrived just before it. Bell Labs filed patents and held a press conference in New York on 30 June 1948, and the coverage was modest compared with how history later viewed the event. The name transistor was proposed by the Bell Labs engineer John R. Pierce, combining the ideas of transfer and resistor and echoing the names of other components such as the varistor. Shockley was not named on the key point-contact patent, and soon afterward he developed the theory of the junction transistor, which became the practical successor.
A common misconception is that the transistor appeared suddenly, or that one inventor did it alone. It followed years of work on semiconductor purification, on rectifiers, and on theory from Bardeen and others, and it required theorists, experimentalists, chemists and technicians working together. Another pitfall is to think that the 1947 device is the one inside modern chips. Today's integrated circuits use field-effect transistors, which are the descendants of the idea that Shockley's group first failed to make work, now enabled by cleanly engineered silicon and oxide interfaces that overcame the surface-state problem.
Read the invention of the transistor as a story in which a failed field-effect experiment led to a theory of surfaces, and that theory in turn led to the contacts, notebook entries and demonstration of December 1947 that began the semiconductor age.