TRANSISTORS AND INTEGRATED CIRCUITS

by

R. J.. Reiman, Historian

On December 23rd, 1947, a small band of scientists at Bell Telephone Laboratories in Murray Hill invented the transistor, one of the most important inventions of the twentieth century. Like the vacuum tube, the transistor could amplify current, detect radio waves, and serve as a switch. It was superior to the vacuum tube, since it turned on instantly, required little power to operate, did not burn out, was inexpensive to make, was highly resistant to vibration and shock, and was miniature in size. It had to be protected from voltage surges however. The transistor was the answer to the weakest link on the developing computers since it could replace the vacuum tube. Its first use was in hearing aids.

In 1906, Lee De Forest had invented the triode, and Edwin Armstrong had devised the circuits using the triode which led to radio. The rise of quantum mechanics gave scientists a theoretical tool for employing semiconductors in electronic circuits. Radar had been invented in the 1930s and semiconductors were tried as a detector of short-waves in spotting low flying aircraft.

Russell S. Ohl of Bell Labs in early 1940 had been astonished when a block of silicon, doped to create regions of positive and negative electrons, could generate half a volt of electricity when a light was shined on the dividing line between the positive and negative zones, i.e. the PN JUNCTION. William Shockley, John Bardeen and Walter Brattain were assembled as a team to research the semiconductor and their aim was to replace the telephone relay in switching stations. In December 1947, Bardeen and Brattain assembled a semiconductor of germanium with two pn junctions and achieved an amplification of 18. This device, the point-contact transistor, was followed by Shockley's bipolar or junction transistor which was easier to manufacture. Bell Labs introduced the point-contact transistor in 1948 and the junction transistor in 1950s. The transistor could be licensed in exchange for royalty and Bell Labs held a course in transistor technology. By 1953, hearing aids used the transistor and by 1954, radios. The first computers to use them appeared in 1957 and 1958 including UNIVAC. In May of 1952, an English engineer, G.W.A. Demmer, called for assembling transistors and associated components into circuits in a block as a means of improving reliability and in miniaturizing electronic devices. The Defense Department was conducting research to this same end for military service.

Robert Noyce, a California physicist, would gather a research team in Palo Alto funded by Fairchild Camera and Instrument Company of New York and the team would concentrate on silicon transistors and integrated circuits. Jack Kilby at Texas Instruments was also working on miniaturization and achieved a phase-shift oscillator which was miniature but not integrated into one solid block. In 1961, Fairchild and TI would introduce the first chips performing Booleon operations such as OR and NOR gates. It would take more work to complete the transfer from tubes to chips for the computer.