William Gardner Pfann (October 27, 1917 – October 22, 1982) was an inventor and materials scientist with

Bell Labs Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial Research and development, research and scientific developm ...

. Pfann is known for his development of

zone melting Zone melting (or zone refining, or floating-zone method, or floating-zone technique) is a group of similar methods of purifying crystals, in which a narrow region of a crystal is melted, and this molten zone is moved along the crystal. The molte ...

which is essential to the semiconductor industry. As stated in an official history of Bell Labs, "Timely invention of zone refining by W.G.Pfann ... was a major contribution that helped bring the impurities in germanium and silicon under control."

Early life

Pfann was born in

Brooklyn Brooklyn () is a borough of New York City, coextensive with Kings County, in the U.S. state of New York. Kings County is the most populous county in the State of New York, and the second-most densely populated county in the United States, be ...

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. Showing unusual facility with materials, in 1935, when he was only eighteen years of age, he started with the Chemical Research Department of Bell Labs. He had no college degree at that time, but attending night school at Cooper Union led to a bachelor's degree in

chemical engineering Chemical engineering is an engineering field which deals with the study of operation and design of chemical plants as well as methods of improving production. Chemical engineers develop economical commercial processes to convert raw materials int ...

in 1940. Pfann was involved in

William Shockley William Bradford Shockley Jr. (February 13, 1910 – August 12, 1989) was an American physicist and inventor. He was the manager of a research group at Bell Labs that included John Bardeen and Walter Brattain. The three scientists were jointl ...

's efforts with Bell Labs to use

semiconductor A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. ...

s to make devices to replace

vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied. The type known as ...

s. The early efforts used germanium. They made high back-voltage germanium rectifiers in 1945. Pfann devised one of the first point-contact transistors: "Specifically, W.G. Pfann had modified the Western Electric 1N26 shielded point-contact (silicon) diode to include two spring-loaded cat whisker point contacts, making a three-electrode configuration with good electrical amplifying properties. This configuration became known at the Type A transistor." He and

Walter Brattain Walter Houser Brattain (; February 10, 1902 – October 13, 1987) was an American physicist at Bell Labs who, along with fellow scientists John Bardeen and William Shockley, invented the point-contact transistor in December 1947. They shared the ...

developed the process of "forming" these transistors to make them more uniform. Pfann also invented a method of bonding fine gold wires to germanium that made the device functional. "The quiet, unassuming man grew steadily in everyone's esteem as he made one valuable contribution after another to the semiconductor research effort."

Breakthrough

The zone melting process that Pfann is known for revolutionized engineering possibilities: "The purity that can be attained by zone refining was absolutely unprecedented in the history of materials processing. Impurity levels of a few parts per million had previously been considered excellent; Pfann's technique improved on this by factors of over 1,000.". In 1952, Pfann published the revelatory article "Principles of Zone-Melting" in the ''Transactions of the

American Institute of Mining, Metallurgical, and Petroleum Engineers The American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) is a professional association for mining and metallurgy, with over 145,000 members. It was founded in 1871 by 22 mining engineers in Wilkes-Barre, Pennsylvania, Uni ...

''. This article applied zone melting in two industrial processes: purification of a solvent material (called zone refining), and production of a uniform distribution of a solute in an ingot (called zone leveling). Three appendices described mathematical models of the processes in zone melting. In 1958, Pfann published the first edition of his text ''Zone Melting'' with John Wiley. A second edition appeared in 1966, and in 1978 publisher Robert E. Krieger of Huntington, New York issued the third edition. In 1962, the journal ''

Science Science is a systematic endeavor that Scientific method, builds and organizes knowledge in the form of Testability, testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earli ...

'' published a short digest of the zone melting method by Pfann. This article concludes by treating the slightly larger topic of temperature gradient zone melting. Pfann describes how and why a drop of gold on a germanium slab moves toward the hottest spot. He says this method was used to "make complex p-n junction shapes for special transistors". He observes the motion of brine on sea ice and proposes the purification of sea water. Further he notes the relation to the physics of geological formations.

Appreciation

In 1973 Pfann was the first to receive the Gordon E. Moore Medal for Outstanding Achievement in Solid State Science and Technology. Pfann was elected to the National Academy of Sciences (U.S.) in 1975. In 1976 the

American Institute of Physics The American Institute of Physics (AIP) promotes science and the profession of physics, publishes physics journals, and produces publications for scientific and engineering societies. The AIP is made up of various member societies. Its corpora ...

awarded him the James C. McGroddy Prize for New Materials. On his passing some coworkers wrote:

Richard Hamming Richard Wesley Hamming (February 11, 1915 – January 7, 1998) was an American mathematician whose work had many implications for computer engineering and telecommunications. His contributions include the Hamming code (which makes use of a ...

used Pfann to illustrate professional development. At first he noted Pfann "didn't know much mathematics and wasn't really articulate." Then Hamming showed him how to use computers and "his shyness, his awkwardness and his inarticulateness fell away and he became much more productive in many other ways." Richard W. Hamming (1986
You and Your Research
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University of Virginia The University of Virginia (UVA) is a public research university in Charlottesville, Virginia. Founded in 1819 by Thomas Jefferson, the university is ranked among the top academic institutions in the United States, with highly selective ad ...

Notes

References

* Kenneth A. Jackson, Harry J. Leamy & Richard S. Wagner (February 1983) "William G. Pfann",

Physics Today ''Physics Today'' is the membership magazine of the American Institute of Physics. First published in May 1948, it is issued on a monthly schedule, and is provided to the members of ten physics societies, including the American Physical Society. ...

36:88. {{DEFAULTSORT:Pfann, William Gardner 20th-century American inventors 1917 births 1982 deaths People from Brooklyn Cooper Union alumni Bell Labs Members of the United States National Academy of Sciences