A Thumbnail History of Electronics

VIII. Transistors

The analogy between the diode and the solid state devices such as the copper oxide rectifier and the crystal detectors of early radio was obvious early on. During the 1920’s, several inventors attempted devices that were intended to control the current in solid state diodes and convert them into triodes. Success, however, had to wait until after World War II, during which the attempt to improve silicon and germanium crystals for use as radar detectors led to improvements both in fabrication and in the theoretical understanding of the quantum mechanical states of carriers in semiconductors and after which the scientists who had been diverted to radar development returned to solid state device development.

George Clarke Southworth (!890-1972) was born and raised in a small Pennsyvania town, received his bachelor’s and master’s degrees from Grove City College and then went to Yale for his PhD. He worked at the Bell Laboratories from its founding in 1934 until retirement. His work on microwave waveguides in the early thirties stimulated the development of radar. When he found that triodes would not function as detectors at microwave frequencies, Southworth turned back to the use of the crystal detectors of the early days of radio. His source for these was the dusty bins of the second-hand, used radio shops of lower Manhattan.

Russell Shoemaker Ohl (1898-1987) has been called the "forgotten man" in the invention of the transistor. Ohl was trained in electrochemistry and graduated from Penn State in 1918. In 1927 he went to work for the Bell Labs Holmdel facility. In 1940, during the course of investigations of the properties of crystal detectors for radar, Ohl enlisted the assistance of Bell chemists in preparing highly purified silicon.  They were able to produce ingots with n and p type silicon at opposite ends of the same silicon melt.   Ohl discovered the silicon photodetector (and the first p-n junction device) when a section was accidentally cut across an (invisible) boundary between p and n regions of a silicon ingot solidifying from a doped melt. The device was shown to Brattain who surmised that rectification was taking place at an internal surface.

Karl Lark-Horovitz (1892-1958) was an assistant professor at the University of Vienna who came to the U.S. in 1926 via Canada, was naturalized in 1936, and became a professor of Physics at Purdue. Lark-Horovitz built  Physics at Purdue into a major research department.  In 1942, Lark-Horovitz and his group began concentrating on the extraction of purified germanium crystals for use as detectors for microwave radar; they also began doping the germanium with other elements to determine how the rectification properties were affected.   In 1943 they succeeded in developing a very high back-voltage unit that was mass-produced for use in radars.  The Purdue physicists openly described their results at technical meetings and to Bell Laboratory personnel who came to Purdue.   They were unaware that the flow of information was one-way;  Bell Laboratory had made semiconductor research company confidential. It is believed that Lark-Horovitz and his group were within a few months of discovery of the transistor.

William Bradford Shockley (1910-1989) was born in London, but grew up in California and was educated at Cal Tech and MIT. He joined the staff of Bell Telephone Laboratories in 1936. Beginning in 1939, Shockley began to seek a way of converting a crystal rectifier into an amplifying device. The war interrupted his work, but it was resumed in 1945 when Shockley returned to Bell Labs as co-leader of the  Solid State Physics research group. The group included Bardeen and Brattain, who invented the point-contact transistor. Shockley invented the junction transistor a few weeks later. Shockley had a grating personality, and both Bardeen and Brattain eventually left the group in irritation. In the 1970’s, Shockley aroused a storm of criticism when he made public a theory of a genetic factor in intelligence which implied an inferiority of blacks; in the 1980’s he aroused a storm of scornful amusement when he announced that he had left frozen samples of his (70-year old) semen for the artificial insemination of women of high intelligence.

Walter H. Brattain (1902-1987) was born in China, the son of an American teaching school in Amoy, and grew up on a ranch in Washington. He received his degrees from Whitman College, the University of Oregon and the University of Minnesota. In 1929 he went to work for Bell Laboratories, investigating the behavior of copper-oxide rectifiers until interrupted by the war, when he became involved in radar silicon detector development.  After, he returned to work in the Solid State Physics group where he and Bardeen invented the point contact transistor. Brittain was the experimentalist, Bardeen the theoretician, but they worked closely together in the laboratory.

John Bardeen (1908-1991), the son of the dean of the University of Wisconsin Medical School, received a PhD in mathematical physics from Princeton, taught at the University of Minnesota, and was the principal physicist at the Naval Ordnance Laboratory during World War II. After the war he was hired by Bell Telephone Laboratories (at nearly twice his academic salary) to work on theoretical problems of solid state physics. The breakthrough that led to the invention of the point-contact transistor in 1948 came when Bardeen developed a theory of the quantum surface states of electrons which led to the conclusion that a charge layer existed at the free surface of semiconductors. Bardeen left Bell Labs in 1951 to become a professor of electrical engineering and physics at the University of Illinois. He shared the 1956 Nobel prize with Shockley and Brattain for their joint invention of the transistor. He also shared the 1972 Nobel prize with Cooper and Schrieffer for the development of the theory of superconductivity, and thus became the first to win two Nobel prizes in Physics.

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