Although the “official” invention of the transistor occurred in 1947, it had several antecedents. Thus, already in 1925, the Austro-Hungarian physicist Julius Edgar Lilienfeld applied for a patent in Canada for what he described as “an apparatus for controlling electric currents”, which is considered the predecessor of current field-effect or unipolar transistors. However, Lilienfeld did not publish any research papers on his devices nor does his patent cite specific examples of a working prototype, and because the production of high-quality semiconductor materials was not available at the time, his ideas for solid-state amplifiers they found no practical solution. In 1934, the German inventor Oskar Heil patented a similar device in Germany and Great Britain, and four years later Robert Pohl and Rudolf Hilsch, also Germans, carried out experiments at the University of Göttingen with potassium bromide crystals using three electrodes, with which they achieved the amplification of 1 Hz signals, but their investigations also did not lead to practical uses.
Meanwhile, in 1938, experimentation at Bell Laboratories (New Jersey, United States) with rectifiers based on copper oxide led William Bradford Shockley, head of the so-called Solid State Physics Group, to think that it was possible to achieve the construction of amplifiers based on semiconductors, instead of vacuum tubes. His intuition was finally confirmed when, on November 17, 1947, physicists John Bardeen and Walter House Brattain, members of the Bell Laboratories team, began a series of experiments in which they observed that by applying two gold point contacts to a germanium crystal, a signal with a higher output power than the input power was produced. Shockley, in collaboration with both, perfected the system and – at the suggestion of engineer John R. Pierce – named it “transistor”. In recognition of this achievement, Shockley, Bardeen, and Brattain were jointly awarded the 1956 Nobel Prize in Physics, “for their research on semiconductors and their discovery of the transistor effect.”
Interestingly, in 1948, the contact transistor was invented independently by German physicists Herbert Mataré and Heinrich Welker while working at the Compagnie des Freins et Signaux, a French subsidiary of the American Westinghouse. Mataré had previous experience developing silicon and germanium crystal rectifiers, from the time he had worked to try to perfect a German radar during World War II. Using this knowledge, he began to investigate the “interference” phenomenon that he had observed in germanium rectifiers during the war. In June 1948, Mataré produced consistent and reproducible results using germanium samples made by Welker, much as Bardeen and Brattain had previously achieved. Realizing that scientists at Bell Laboratories had already patented the transistor before them, the Franco-Germans rushed to put their device into production under the name “transistron”, for use in France’s telephone network.