Electrochemistry has also made a profound contribution to the age of computers, through the work of Norman Bruce Hannay (1921–1996). During World War II, Hannay worked on gaseous diffusion for the Manhattan Project, right after receiving his Ph.D. from Princeton in physical chemistry. His first civilian project at Bell Laboratories was to investigate the mechanism by which electrically charged particles are emitted from the incandescent light cathodes of vacuum tubes—that is, along the same lines that Irving Langmuir at General Electric had pioneered. But at the end of 1947 Hannay's colleagues at Bell Labs invented the transistor, and his research program changed radically, to ensuring a high level of purity in the semiconductors used in transistors and later in integrated circuit chips.
Hannay's new job was to develop a mass spectrograph to analyze solids for trace impurities. Then he was chosen to lead both chemical and physical aspects of the silicon program. Although the first transistors were made from germanium, industry soon targeted silicon, with its lower cost and potential for developing a good oxide layer. To avoid contact with any other substance that would contribute impurities to silicon, Hannay's group devised a method of growing silicon crystals in a vacuum, relying on mere surface tension to suspend the crystals. This method is still used to make substrates for integrated circuit chips. In 1953 Bell Labs and Texas Instruments simultaneously heralded the arrival of the silicon transistor. Through the 1950s Hannay and his colleagues investigated other semiconductors, including gallium arsenide—the preferred material for semiconductor lasers, which are the basis for optical communication systems and have many other purposes today.