A little over twenty-five years ago, on December 23rd, 1947, to be exact, a group of scientists at Bell Laboratories built a one-stage amplifier circuit around the world's first transistor, giving birth to a whole new era of electronics and communications. But the beginning of the story was not in 1947, but long before. There had been hints of amplifica- tion in semiconductors as early as the 1920s but few experimenters could du- plicate the results. Nobody realized the effect of semiconductor impurities nor understood the action of semiconductor materials. In 1930 Dr. Julius Lilienfeld, a Ger- man physicist, actually patented a semi- conductor amplifier that could be com- pared to today's mosfet. Although Dr. Lilienfeld's amplifier worked, it could not be duplicated by other workers, and it slowly slipped into oblivion. In 1939, Dr. William Shockley made an entry into his lab notebook at Bell Labs, "It has today occurred to me that an amplifier using semiconductors rather than vacuum is in principle possible." It was nearly eight years before this concept would bear fruit. A large part of this period was spent in learning more about that old bugaboo, semiconductor impuri ties. The 1 N21 crystal detector, developed during World War I I and the workhorse of wartime radar receivers, provided some of the impetus. After the war a solid-state research team at Bell Labs, co-headed by Dr. Shockley, started experimenting with germanium and silicon, two semiconduc- tors that were easy to work with. As one of the group says today, "We felt that the area was so fertile that you could devise an experiment in the morning, go out in the lab and try it in the afternoon, and then write a paper about it that evening."
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