The Innovators: How a Group of Inventors, Hackers, Geniuses, and Geeks Created the Digital Revolutio - Isaacson Walter - Страница 38
- Предыдущая
- 38/155
- Следующая
Before Shockley and Brattain could figure out why it had failed, World War II intervened. Shockley went off to become a research director in the Navy’s antisubmarine group, where he developed analyses of bomb detonation depths to improve attacks on German U-boats. He later traveled to Europe and Asia to help B-29 bomber fleets use radar. Brattain likewise left for Washington to work on submarine-detection technologies for the Navy, focusing on airborne magnetic devices.
THE SOLID-STATE TEAM
While Shockley and Brattain were away, the war was transforming Bell Labs. It became part of the triangular relationship that was forged among the government, research universities, and private industry. As the historian Jon Gertner noted, “In the first few years after Pearl Harbor, Bell Labs took on nearly a thousand different projects for the military—everything from tank radio sets to communications systems for pilots wearing oxygen masks to enciphering machines for scrambling secret messages.”10 The staff doubled in size, to nine thousand.
Having outgrown its Manhattan headquarters, most of Bell Labs moved to two hundred rolling acres in Murray Hill, New Jersey. Mervin Kelly and his colleagues wanted their new home to feel like an academic campus, but without the segregation of various disciplines into different buildings. They knew that creativity came through chance encounters. “All buildings have been connected so as to avoid fixed geographical delineation between departments and to encourage free interchange and close contact among them,” an executive wrote.11 The corridors were extremely long, more than the length of two football fields, and designed to promote random meetings among people with different talents and specialties, a strategy that Steve Jobs replicated in designing Apple’s new headquarters seventy years later. Anyone walking around Bell Labs might be bombarded with random ideas, soaking them up like a solar cell. Claude Shannon, the eccentric information theorist, would sometimes ride a unicycle up and down the long red terrazzo corridors while juggling three balls and nodding at colleagues.III It was a wacky metaphor for the balls-in-the-air ferment in the halls.
In November 1941 Brattain had made his last journal entry, into his notebook #18194, before leaving Bell Labs in Manhattan for his wartime service. Almost four years later, he picked up that same notebook in his new lab in Murray Hill and began anew with the entry “The war is over.” Kelly assigned him and Shockley to a research group that was designed “to achieve a unified approach to the theoretical and experimental work of the solid state area.” Its mission was the same as they had before the war: to create a replacement for the vacuum tube using semiconductors.12
When Kelly sent around the list of who was going to be on the solid-state research group, Brattain marveled that it included no losers. “By golly! There isn’t an s.o.b. in the group,” he recalled saying, before pausing to worry, “Maybe I was the s.o.b. in the group.” As he later declared, “It was probably one of the greatest research teams ever pulled together.”13
Shockley was the primary theoretician, but given his duties as the team’s supervisor—he was on a different floor—they decided to bring in an additional theorist. They chose a soft-spoken expert in quantum theory, John Bardeen. A child genius who had skipped three grades in school, Bardeen had written his doctoral thesis under Eugene Wigner at Princeton and during his wartime service in the Naval Ordnance Laboratory discussed torpedo design with Einstein. He was one of the world’s greatest experts on using quantum theory to understand how materials conduct electricity, and he had, according to colleagues, a “genuine ability to collaborate easily with experimentalist and theorist alike.”14 There was initially no separate office for Bardeen, so he ensconced himself in Brattain’s lab space. It was a smart move that showed, once again, the creative energy generated by physical proximity. By sitting together, the theorist and the experimentalist could brainstorm ideas face-to-face, hour after hour.
Unlike Brattain, who was voluble and talkative, Bardeen was so quiet that he was dubbed “Whispering John.” To understand his mumbling, people had to lean forward, but they learned that it was worth it. He was also contemplative and cautious, unlike Shockley, who was lightning-quick and impulsively spouted theories and assertions.
Their insights came from interactions with each other. “The close collaboration between experimentalists and theorists extended through all stages of the research, from the conception of the experiment to the analysis of the results,” said Bardeen.15 Their impromptu meetings, usually led by Shockley, occurred almost every day, a quintessential display of finish-each-other’s-sentence creativity. “We would meet to discuss important steps almost on the spur of the moment,” Brattain said. “Many of us had ideas in these discussion groups, one person’s remarks suggesting an idea to another.”16
These meetings became known as “blackboard sessions” or “chalk talks” because Shockley would stand, chalk in hand, scribbling down ideas. Brattain, ever brash, would pace around the back of the room and shout out objections to some of Shockley’s suggestions, sometimes betting a dollar they wouldn’t work. Shockley didn’t like losing. “I finally found out he was annoyed when he paid me off once in ten dimes,” Brattain recalled.17 The interactions would spill over into their social outings; they often played golf together, went out for beer at a diner called Snuffy’s, and joined in bridge matches with their spouses.
THE TRANSISTOR
With his new team at Bell Labs, Shockley resurrected the theory he had been playing with five years earlier for a solid-state replacement for the vacuum tube. If a strong electrical field was placed right next to a slab of semiconducting material, he posited, the field would pull some electrons to the surface and permit a surge of current through the slab. This potentially would allow a semiconductor to use a very small signal to control a much larger signal. A very low-powered current could provide the input, and it could control (or switch on and off) a much higher-powered output current. Thus the semiconductor could be used as an amplifier or an on-off switch, just like a vacuum tube.
There was one small problem with this “field effect”: when Shockley tested the theory—his team charged a plate with a thousand volts and put it only a millimeter away from a semiconductor surface—it didn’t work. “No observable change in current,” he wrote in his lab notebook. It was, he later said, “quite mysterious.”
Figuring out why a theory failed can point the way to a better one, so Shockley asked Bardeen to come up with an explanation. The two of them spent hours discussing what are known as “surface states,” the electronic properties and quantum-mechanical description of the atom layers closest to the surface of materials. After five months, Bardeen had his insight. He went to the blackboard in the workspace he shared with Brattain and began to write.
Bardeen realized that when a semiconductor is charged, electrons become trapped on its surface. They cannot move about freely. They form a shield, and an electric field, even a strong one a millimeter away, cannot penetrate this barrier. “These added electrons were trapped, immobile, in surface states,” Shockley noted. “In effect, the surface states shielded the interior of the semiconductor from the influence of the positively charged control plate.”18
The team now had a new mission: find a way to break through the shield that formed on the surface of semiconductors. “We concentrated on new experiments related to Bardeen’s surface states,” Shockley explained. They would have to breach this barrier in order to goose the semiconductor into being able to regulate, switch, and amplify current.19
- Предыдущая
- 38/155
- Следующая
