Exclusive interview with Professor Shuji Nakamura, inventor of the first high brightness gallium nitride (GaN) LED

The global LED industry is in a constant a flux, with breakthrough innovations in lighting design and technology. To gain more insight on future prospects of the LED industry, LEDinside recently conducted an exclusive interview with Professor Shuji Nakamura, inventor of the first high brightness gallium nitride (GaN) LED, a revolutionary source of light which won him the 2006 Millennium Technology Prize, the engineering equivalent of a Nobel Prize.

Professor Shuji Nakamura, inventor of the first high brightness gallium nitride (GaN) LED

Energy efficiency is the key driving force behind consumer purchases

Addressing future developments in the LED lighting market, Professor Nakamura expressed that in order for rapid adoption of LED lighting to take place in general illumination, its full energy-saving potential has to be achieved. There has to be technological advancements such as preventing efficiency droop, improving extraction efficiency (approximately 90%), and increasing reliability through achieving longer life time. “Without improvements in these aspects, LEDs for general illumination is quite tough,” he added.

Another key to accelerating the adoption of LED lighting in general illumination is cost of ownership. Reducing cost of ownership requires a combination of lowering the cost of LED light bulb and lowering energy consumption, thereby making cost savings over time compelling enough for consumers to purchase the LED light bulb for household use.

Progress of LED lighting adoption in regional markets

Comparing the progress of LED lighting adoption in regional markets, Nakamura explained that, awareness toward energy-efficiency is relatively high in Japan, where consumers pay attention to lighting efficiency and quality to light. However, regulations in the Japan market may hamper the development of LED lighting. In comparison, the Korean market is more price sensitive; therefore, the retail price of LED bulbs is a major hurdle for lighting manufacturers. Nakamura envisioned that one day, the cost of LED bulbs would fall to the same level as incandescent bulbs.

LED backlighting in the portable devices segment

The mobile phone and portable devices market, such as notebook and tablet PC, is a segment where LED backlighting is widely adopted. With the continual improvements in brightness and energy efficiency, LED backlighting is expected to become mainstream. Nakamura noted, “Interestingly, LED was developed even before cellular phone was introduced to the market.” [The first practical visible-spectrum (red) LED was developed in 1962 by Nick Holonyak Jr., while the first handheld cellular phone was demonstrated by Martin Cooper in 1973.]

The target for luminous efficacy is at 200 lumens/watt for LED lighting products, but Nakamura is optimistic about its development, indicating that 250 lumen/watt is feasible by 2015.

Professor Nakamura is currently a professor at the Materials Department of the College of Engineering, University of California, Santa Barbara.

About Shuji Nakamura
Shuji Nakamura was born on May 22, 1954 in Ehime, Japan. He obtained B.E., M.S., and Ph.D. degrees in Electrical Engineering from the University of Tokushima, Japan in 1977, 1979, and 1994, respectively. He joined Nichia Chemical Industries Ltd in 1979. In 1988, he spent a year at the University of Florida as a visiting research associate. In 1989, he started the research of blue LEDs using group-III nitride materials. In 1993 and 1995, he developed the first group-III nitride-based blue/green LEDs. He also developed the first group-III nitride-based violet laser diodes (LDs) in 1995.
The development of nitride based semiconductors, by Prof. Nakamura, represents one of the most important achievements in the materials science of semiconductors in the last 30 years. Specifically, the discovery of p-type doping in Gallium Nitride (GaN) and the development of blue, green, and white light emitting diodes (LEDs) and blue laser diodes (LDs) has enabled energy efficient lighting and displays. Dr. Nakamura discovered that p-type GaN films could be obtained by doping GaN with Mg, with successive post-thermal annealing in nitrogen ambient at temperatures above 400°C. Dr. Nakamura also developed InGaN films of the highest crystal quality which enabled the realization of bright blue double heterostructure light emitting devices. These achievements have resulted in great benefits to mankind through their use in devices for energy efficient solid-state lighting, displays, medicine, and the next generation of Blu-Ray optical storage. The general conclusion among scientists at this time is that Dr. Nakamura’s inventions are so reliable and energy efficient that they are destined to replace Thomas Edison’s light bulb and save the world billions of dollars in energy costs.
Professor Nakamura has received a number of awards in honor of his work, including: the Nishina Memorial Award (1996), MRS Medal Award (1997), IEEE Jack A. Morton Award, the British Rank Prize (1998), the Benjamin Franklin Medal Award (2002), the Millennium Technology Prize (2006), the Czochralski Award (2007), the Prince of Asturias Award for Technical Scientific Research (2008), and most recently The Harvey Award (2009). He was elected as a member of the U.S. National Academy of Engineering (NAE) in 2003. Since 2000, he has been a professor of Materials at the University of California, Santa Barbara. He holds more than 100 patents and has published more than 400 papers in his field. Professor Nakamura is the Reasearch Director of the Solid State Lighting & Energy Center.

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