Few births are easy. Even fewer result in a Nobel Prize, and hardly any at all are the work of three men. This 1965 film from the AT&T archives is a retrospection on the birth of the transistor nine years after its creators, [Walter Brattain], [John Bardeen], and [William Shockley] received a Nobel Prize in Physics for their discovery and implementation of the transistor effect.
The transistor is the result of the study of semiconductors such as germanium. Prior to the research that led directly to the transistor, it was known that the conductivity of semiconductors increases when their temperature is raised. The converse is true for metals such as tungsten. Semiconductor conductivity also increases when they are exposed to light. Another key to their discovery is that when a metal such as copper is in contact with a semiconductor, conductivity is less in one direction than the other. This particular property was exploited in early radio technology as seen in crystal radios, for copper oxide rectifiers used in telephony, and for microwave radar in WWII.
After WWII, AT&T’s Bell Labs put a lot of time and research into the study of semiconductors, as their properties weren’t fully understood. Researchers focused on the simplest semiconductors, silicon and germanium, and did so in two areas: bulk properties and surface properties. During this time, [Shockley] proposed the field effect, supposing that the electrons near the surface of a semiconductor could be controlled under the influence of an external electric field.
This effect would make for great strides in the field of amplification. [Bardeen, Brattain, and Shockley] tested the contact potential of a metal with respect to the surface of a germanium slab. [Brattain] offered that moving the metal conductor across the germanium would produce current flow in a wire connecting the two, and that adding an electrolyte would result in amplification. To experiment, [Bardeen] advocated the model you see below: a piece of germanium with a drop of water for the electrolyte, and a waxed wire penetrating the water to contact the germanium. A second wire makes contact with the water, and both circuits are equipped with a potential.
Sure enough, the current on the left influenced the potential through the waxed point, and they had themselves a working semiconductor amplifier. This experiment was vital to the development of the transistor.
The experiment was not without its problems, however. The water electrolyte evaporated too quickly, so they tried glycol borate. That worked much better, but the circuit wouldn’t amplify above 8Hz. They replaced the electrolyte with a thin wafer of gold and used a contact near the edge of the gold instead of the waxed point. [Bardeen, Brattain, and Shockley] dubbed the resulting phenomenon ‘the transistor effect’. Two days before Christmas, 1947, they spoke over the circuit and heard a distinct gain. This arrangement would become the first production line model, known as the point contact transistor.
Further research led to the growth of single crystals of germanium, which made the junction transistor possible. The alloy transistor was developed a few years later, in 1951. These had limited frequency and could only be produced one at a time. In 1954, the diffused base transistor, a high-frequency, high-speed device, was developed.
And this is what was intended all along: an extremely reliable device that could transmit and amplify high-frequency signals at very high speeds and very low power levels. No wonder they won the Nobel Prize.
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