1926 AD to 1962 AD |
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| The transistor and subsequently the integrated circuit must certainly qualify as two of the greatest inventions of the twentieth century. These devices are formed from materials known as semiconductors, whose properties were not well-understood until the 1950s. However, as far back as 1926, Dr. Julius Edgar Lilienfield from New York filed for a patent on what we would now recognize as an NPN junction transistor being used in the role of an amplifier (the patent title was "Method and apparatus for controlling electric currents"). |
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| Unfortunately, serious research on semiconductors didn't really
commence until World War II. At that time it was recognized that devices formed from semiconductors had potential as amplifiers and switches, and could therefore be used to replace the prevailing technology of vacuum tubes, but that they would be much smaller, lighter, and would require less power. All of these factors were of interest to the designers of the radar systems which were to play a large role in the war. |
Bell Laboratories in the United States began research into
semiconductors in 1945, and physicists William Shockley, Walter Brattain and John Bardeen
succeeded in creating the first point-
contact germanium transistor on
the 23rd December, 1947 (they took a break for the Christmas holidays before publishing
their achievement, which is why some reference books state that the first transistor was
created in 1948). In 1950, Shockley invented a new device called a bipolar junction transistor, which was more reliable, easier and cheaper to build, and gave more consistent results than point-contact devices. (Apropos of nothing at all, the first TV dinner was marketed by the C.A. Swanson company three years later.) |
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| By the late 1950s, bipolar transistors were being manufactured out of silicon rather than germanium (although germanium had certain electrical advantages, silicon was cheaper and easier to work with). Bipolar junction transistors are formed from the junction of three pieces of doped silicon called the collector, base, and emitter. The original bipolar transistors were manufactured using the mesa process, in which a doped piece of silicon called the mesa (or base) was mounted on top of a larger piece of silicon forming the collector, while the emitter was created from a smaller piece of silicon embedded in the base. | ||
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| In 1959, the Swiss physicist Jean Hoerni invented the planar process, in which optical lithographic techniques were used to diffuse the base into the collector and then diffuse the emitter into the base. One of Hoerni's colleagues, Robert Noyce, invented a technique for growing an insulating layer of silicon dioxide over the transistor, leaving small areas over the base and emitter exposed and diffusing thin layers of aluminum into these areas to create wires. The processes developed by Hoerni and Noyce led directly to modern integrated circuits. | In 1962, Steven Hofstein and Fredric Heiman at the RCA
research laboratory in Princeton, New Jersey, invented a new family of devices called
metal-oxide semiconductor field-effect
transistors (MOS FETs for short). Although these transistors were somewhat slower than bipolar transistors, they were cheaper, smaller and used less power. Also of interest was the fact that modified metal-oxide semiconductor structures could be made to act as capacitors or resistors. |
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| These notes are abstracted from the book Bebop BYTES Back (An Unconventional Guide to Computers) Copyright Information |
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