- Brilliant! Shuji Nakamura and the Revolution in Lighting Technology
The "revolution" in question is the universal replacement of filament and fluorescent lighting by LEDs (light-emitting diodes). That revolution is only just beginning, but, if Bob Johnstone's readable and convincing thesis is correct, then LEDs will soon be used for almost every lighting application and will significantly reduce the demand for electricity.
Accounts of scientific developments, business history, and a personal story are intertwined in this book. The first LEDs in 1962 consisted of a layer a few atoms thick of the compound semiconductor material, gallium arsenide. Robust and taking very little power, they were ideal as indicators. They could give only red light, but their high efficiency compared with all other electric lights led people to ask whether a bright white LED could be developed for general illumination. The problem was solved by Shuji Nakamura, born in 1954 on Shikoku, the smallest of Japan's four main islands. Nakamura had studied electrical engineering at a local university, where he became fascinated with solid-state physics and obtained a master's degree. [End Page 479]
Unusually for a Japanese, he had married while a student, and he preferred to stay in rural Shikoku rather than take a job with one of the big electrical firms on the main islands. He joined Nichia Chemical Industries, a small firm manufacturing phosphors for fluorescent lamps and television screens. The founder of Nichia, Nobuo Ogawa, had first seen fluorescent lighting in the Philippines during World War II. Impressed, he went into phosphor development and manufacture after the war. The elderly Ogawa must have seen possibilities in Nakamura: he gave him a free hand in his choice of research topics and allowed him to purchase very expensive equipment.
Nakamura saw that the key to solving the problem was the development of an efficient bright blue LED. If he could achieve that, he could also make a green LED, and by combining red, green, and blue LEDs produce white. Although blue LEDs based on silicon carbide were being developed by other researchers, their efficiency was very low. Nakamura's studies led him to conclude that the blue LED should be based on gallium nitride, but forming a thin, single-crystal layer of gallium nitride was extremely difficult. Johnstone explains the solid-state physics involved and describes the complex equipment which deposits the semiconductor materials from vapor onto a substrate. Nakamura announced his bright blue LED in 1993. Two years later, at his suggestion, Nichia began manufacturing white LEDs based on the blue LED combined with a yellow phosphor which it was already manufacturing.
As well as the physics, Johnstone describes Japanese industrial culture where the expectation is that an employee stays with one employer for life. But when Ogawa died, the new Nichia boss did not support Nakamura's work. By this time Nakamura was becoming known internationally, attending and contributing to physics conferences around the world. Friends urged a move to the United States, and after much soul-searching he resigned from Nichia and became a professor at the University of California at Santa Barbara in 2000. By then Nakamura had obtained numerous patents. The new Nichia management accused him of leaking trade secrets, and Nakamura did not feel that Nichia had rewarded him properly. A series of acrimonious legal battles ended in 2005 when the High Court in Tokyo awarded him 843 million yen (about eight million dollars).
Surprisingly, although there is a photograph of a handful of LEDs, there is no simple drawing of one. Johnstone says they are cut from a gallium nitride wafer "the diameter of an Oreo cookie," which is not helpful for non-American readers (though my American friends tell me that an Oreo cookie is about 5 cm in diameter). It is also irritating that, writing of the end of the incandescent lamp, he implies that Edison was the sole inventor. But, since he has given us a comprehensive account of the latest electric lighting, this lapse in the early history...