After William Shockley's theories about p-n junctions had been validated by tests (1948 Milestone), fabricating a working junction transistor still presented formidable challenges. The main problem was lack of sufficiently pure, uniform semiconductor materials. Bell Labs chemist Gordon Teal argued that large, single crystals of germanium and silicon would be required, but few - including Shockley - were listening.
With little support from management, Teal built the needed crystal-growing equipment himself, with help from mechanical engineer John Little and technician Ernest Buehler. Based on techniques developed in 1917 by the Polish chemist Jan Czochralski, he suspended a small "seed" crystal of germanium in a crucible of molten germanium and slowly withdrew it, forming a long, narrow, single crystal. Shockley later called this achievement "the most important scientific development in the semiconductor field in the early days."
Employing this technique, Bell Labs chemist Morgan Sparks fabricated p-n junctions by dropping tiny pellets of impurities into the molten germanium during the crystal-growing process. In April 1950, he and Teal began adding two successive pellets into the melt, the first with a p-type impurity and the second n-type, forming n-p-n structures with a thin inner, or base, layer. A year later, such “grown-junction transistors” surpassed the best point-contact transistors in performance. Bell Labs announced this advance on July 4, 1951 in a press conference featuring Shockley.
Czochralski, J. "Ein neues Verfahren zur Messung der Kristallisationsgeschwindigkeit der Metalle" Zeitschrift fèur Physikalische Chemie, Vol. 92 (1917) p. 219
Teal, Gordon K. "Methods of Producing Semiconductive Bodies," U. S. Patent 2,727,840 (Filed June 15, 1950. Issued December 20, 1955)
Sparks, Morgan and Teal, Gordon K. "Method of Making P-N Junctions in Semiconductor Materials," U. S. Patent 2,631,356 (Filed June 15, 1950. Issued March 17, 1953)
Teal, Gordon K. and Little, John B. "Growth of Germanium Single Crystals," Physical Review, Vol. 78 (1950) p. 647.
Shockley, William, Sparks, Morgan and Teal, Gordon K., "p-n Junction Transistors," Physical Review, Vol. 83, No. 1 (July 1951) pp.151-162.
Sparks, Morgan. "The Junction Transistor," Scientific American (March 1952) pp. 29-32.
Teal, Gordon K. "Single Crystals of Germanium and Silicon - Basic to the Transistor and Integrated Circuit," IEEE Transactions on Electron Devices, Vol. ED-23, No. 7 (July 1976) pp. 621-39.
Augarten, Stan. "Solid-State Electronics Goes Commercial," State Of The Art: A Photographic History of the Integrated Circuit. (New Haven & New York: Ticknor and Fields, 1983) p. 4.
Riordan, M. & Hoddeson, L. Crystal Fire: The Birth of the Information Age. (New York: W. W. Norton, 1997) p.168-194.
Lécuyer, Christophe and Brock, David C. "The Materiality of Microelectronics" History and Technology Vol. 22, No. 3 (September 2006) pp. 301-325.