A Dose of Our Own Medicine
ea culpa. A study in the June 1 New England Journal of Medicine shows that we journalists could probably do our jobs better. Stories about new medications often exaggerate benefits, ignore risks, overlook costs and fail to comment on financial ties to drug manufacturers. The study, co-authored by medical researchers and a journalist, analyzed 207 news stories and found that only 124 reported benefits quantitatively. And 103 of those gave the results in relative terms only—articles about the drug alendronate, for example, touted its ability to reduce hip fractures in people with osteoporosis by 50 percent without mentioning that the reduction took the risk down from an already low 2 percent to 1 percent. Only 98 stories mentioned possible harm from the drugs, and only 63 cited cost. An accompanying editorial reminds journalists to be skeptical. The same counsel applies to consumers of medical news. —Steve Mirsky
Shuji Nakamura beat the titans to blue LEDs and lasers, potentially revolutionizing lighting and data storage o
SANTA BARBARA, CALIF.—I press a button on the pocket light-emitting diode tester, and three specks of plastic and semiconductor shoot out blue and green rays intense enough to hurt my eyes. The two blue devices emit a furious cerulean with the slightest hint of violet. The green is sharp and rich—not that ghastly yellowish hue that had to do if you wanted a "green" LED until recently.
Until, that is, the man who is grinning at me, Shuji Nakamura, got some very bright ideas.
Nakamura, the newest addition to the engineering faculty at the University of California at Santa Barbara, stunned colleagues late in 1999, when he revealed that he was leaving Nichia Corporation, a once obscure Japanese maker of phosphors for cathode-ray tubes and fluorescent lights. Thanks to Nakamura, Nichia now fabricates the world's best blue and green LEDs and the only commercially avail able blue-violet semiconductor lasers. At a time when invention is dominated by faceless teams at huge corporations, he showed that an inventor with enough talent and determination can triumph despite daunting disadvantages.
For more than 25 years, LEDs were like a third of a rainbow. Red, orange, yellow and that yellowish green were all you could get. Engineers wanted blue and true green because with those colors, along with the red they already had, they could build fabulous things, such as a white-light-emitting device as much as 12 times more efficient and longer-lasting than an ordinary lightbulb. Small wonder, then, that analysts say LEDs are poised to revolutionize the lighting industry and move beyond their familiar role as mere indicator lights. In the meantime, colored LEDs are being deployed as traffic lights and in displays, the biggest being the eight-story-tall Nasdaq display in New York City's Times Square. And a blue semiconductor laser, similar to an LED, will soon quadruple the storage capacity of DVD and CD players and the resolution of laser printers.
Most of the milestones on the way to these optoelectronics triumphs took place, oddly enough, on the island of Shikoku, something of a backwater in the Japanese chain. There Nakamura was born, raised and educated at the University of Toku-shima. He earned a master's degree in 1979 and then took a job at Nichia, basically because it was nearby, on Shikoku.
Right after he joined the company, the young Nakamura was put to work on gallium phosphide crystals, which were used to make red and yellowish green LEDs. The research budget was tight, so Naka-mura had to build all the necessary equipment on his own. That meant he had to teach himself such tricky and esoteric chores as welding quartz.
In 1982 he began producing gallium phosphide crystals that were as good as anything Nichia's larger rivals—including Sanyo, Sharp, Stanley Electric, Rohm and Toshiba—were putting out. Unfortunately, most customers bought from the larger, well-known companies, leaving Nichia only a sliver of the LED pie. Over the next six years, Nakamura went through essentially the same frustrations with gallium arsenide crystals and then with complete red and infrared LEDs.
Strangely, Nichia's sales department blamed Nakamura for the disappointing figures, and some senior co-workers wanted him to resign. "I became very angry," Nakamura recalls. But rather than let them drive him away, he resolved to aim higher. He knew that optoelectronics' holy grail was a blue-light emitter, and he decided to get into the fray.
Nakamura's boss, the R&D manager, thought he was "crazy," as he tells it, and wouldn't support him. So in January 1988 Nakamura bypassed his boss and marched into the office of Nichia's CEO, Nobuo Ogawa, to demand $3.3 million in research funding and a year off to go to the University of Florida to study a semiconductor-fabrication technology called metallorganic chemical vapor deposition (MOCVD) that channeled hot gases to create thin films on substrates. MOCVD was then emerging as the technology of choice for producing certain exotic semiconductors. It was an outrageous move in the feudal, seniority-based Japanese corporate system. Much to Naka-mura's amazement, however, Ogawa simply agreed to all his terms.
At the Florida lab, he found that only parts that could be assembled into an MOCVD system were available. And it turned out that Nakamura was just the guy to do it: lacking a doctorate and a list of published papers, Nakamura says he was "treated like an engineer, not a researcher." Building the MOCVD machine took him 10 months, working seven days a week, 16 hours a day.
Returning to Nichia in March 1989 to begin work on blue-light devices, he had to choose between the two main semiconductor types. No contest: Nakamura picked gallium nitride, because all the giants of industry and academia were pursuing zinc selenide, and he was sick of playing the same game as the titans. They avoided gallium nitride because a necessary form of the material (called p-type) could not be made in commercially useful amounts.
Over the next 10 years, as he coaxed more and more light out of gallium nitride
SHUJI NAKAMURA: FAST FACTS
• Born in Seto-cho, Nishiuwa-gun, Ehime Prefecture, on Shikoku island, in 1954
• Wife, Hiroko Nakamura, and three daughters, Hitomi, Fumie and Arisa
• As a boy, he was inspired by the comic book Tetsuwan Atom, about a robot, written by the great Japanese comic artist Osamu Tezuka
• Favorite foods: Larmen and udon noodles; uni (sea urchin) sushi and eclipsed his competitors, Nakamura put together a string of achievements that for genius and sheer improbability is as impressive as any other accomplishment in the history of semiconductor research. And it is all documented in a trail of literature almost as stunning. Between 1991 and 1999 he authored or co-authored 146 technical papers, six books and 10 book chapters on gallium nitride semiconductors. The output is all the more amazing because it was accomplished in secret: CEO Ogawa, fearing disclosure of secrets, forbade Nichia employees from publishing or speaking at conferences. By 1994 Nakamura's body of work was so prodigious that the University of Tokushima awarded him a doctorate in engineering.
The foundation of Nakamura's success was a deep understanding not only of semiconductor crystal growth but, more important, of the machines that accomplished it. The active layer in his experimental LED, where electrons and electron deficiencies called holes combined and released photons, was a thin film of indium gallium nitride grown on gallium nitride. Commercially available MOCVD machines could not grow an indium gallium nitride film good enough to emit light brightly, so Nakamura began modifying his setup. From his years of building reactors, furnaces and MOCVD machines, he knew how to weld quartz—which enabled him to alter quickly the conduits that conveyed the superhot reactants in an MOCVD machine.
Every morning Nakamura modified the reactor. Every afternoon he grew four or five samples. After about two years, he hit on the configuration that would put him way ahead of the pack. In a conventional MOCVD system, semiconductors are created as reactant gases flow over a substrate, parallel to its surface. In Naka-mura's system, one gas flows parallel to and the other flows perpendicularly to the surface. The configuration, which he calls "two-flow MOCVD," suppresses thermal convection currents and cools the reactant gases, leading to more stable reactions and better films.
The other major obstacle to a mass-producible LED fell in 1992, when he invented a heat-based process to produce commercial quantities of p-type gallium nitride. But to get a dependable laser, he still had to find a way to minimize the enormous density of defects in gallium nitride crystals. Taking inspiration from a talk by NEC researchers in 1997, Naka-mura grew a layer of silicon dioxide strategically within the gallium nitride crystal to block some of the defects. By the end of the year he had increased the lifetime of his blue semiconductor lasers from about 300 hours to the 10,000 hours needed for a commercial product.
Early in 1999 Nichia began selling five-milliwatt blue semiconductor lasers and, later, violet ones with a wavelength of 405 nanometers, the shortest ever for a semiconductor laser. Nakamura also produced blue lasers with power levels above 30 milliwatts; he declines to give a precise figure (the levels necessary for laser printers are around 50 to 60 milliwatts).
Last October, having done everything he wanted to with gallium nitride and weary of a Japanese industrial R&D system that he characterizes as "communist," Nakamura decided to leave Nichia. Although his inventions had swelled Nichia's annual profits from under $100 million to over $400 million, Nakamura was being paid only $100,000 a year, he says. Among the 17 job offers he got in the space of four weeks was one from a U.S. company that offered him $500,000 a year and stock options worth $10 million. "It was unbelievable to me," he relates.
He was ready to sign with the company, but a professor at one of the universities that was courting him advised him that if he took an industrial job, Nichia— which held the patents on all his gallium nitride breakthroughs—would sue him if he did anything even remotely related. After mulling things over, Nakamura accepted an offer from the University of California at Santa Barbara.
Having earned a nice spot in the semiconductor pantheon, the 46-year-old Nak-amura is as restless and driven as ever. Asked what he wants to do now, he replies, "Here I can start a venture company—in five or 10 years, if I could invent a new device." He says, laughing: "I want to achieve the American dream." — Glenn Zorpette
For an enhanced and more detailed version of this story, go to www.sciam.com
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