218th ECS Meeting | Las Vegas, NV | Oct. 11, 2010
Current and Future Status of Nitride-based Solid State Lighting
In his plenary talk, Shuji Nakamura will describe the current status of III-nitride based light emitting diodes (LEDs) and laser diodes. Recently, nitride-based white LEDs have been used for many application such as LCD TV backlight, lighting for inside/outside applications and others. The efficiency of those white LEDs are around 150 lumen/W. On the laser diodes, high efficient and high power blue laser diodes have been developed. On the green laser diodes, the output power is still not as high at the wavelength of around 525 nm.
Shuji Nakamura obtained BE, MS, and PhD 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 research on blue LEDs using group-III nitride materials. In 1990, he developed a novel MOCVD system for GaN growth, which was named Two-Flow MOCVD. Using this system, he was able to grow the highest crystal quality of GaN-based materials.
In 1991, Dr. Nakamura obtained p-type GaN films by thermal annealing for the first time and was able to clarify hydrogen passivation as a hole compensation mechanism. For many researchers, working since the beginning of GaN research in 1960s, this hydrogen passivation of the acceptors had hindered the ability to obtain p-type GaN films. In 1992, he was also able to grow the first InGaN single crystal layers, which showed the first band-to-band emission in PL and EL at room temperature. These InGaN layers have been used for an emitting layer in all blue/green/white LEDs and all violet/blue/green semiconductor lasers. Without his invention of InGaN layers, there would have been no blue/green/white LEDs and no violet/blue/green semiconductor laser diodes.
In 1993 and 1995, Dr. Nakamura developed the first group-III nitride-based high-brightness blue/green LEDs. He also developed the first group-III nitride-based violet laser diodes (LDs) in 1995. In 1996, his former company, Nichia, started selling white LEDs using his invention of blue LEDs. These white LEDs have been used for all kinds of lighting applications in order to save energy consumption. The electric consumption of white LEDs is about one tenth that of conventional incandescent bulb lamps. In 1999, Nichia started selling violet laser diodes for the application of blue-ray DVDs. Without his invention of violet laser diodes, the blue ray DVD would not have been realized.
Dr. Nakamura moved to the U.S. from Japan in 2000 where he became a professor in the Materials Department at the University of California at Santa Barbara (UCSB). In 2007, he and his coworkers at UCSB succeeded in the first lasing of nonpolar/semipolar GaN-based semiconductor laser diodes. In 2009, they achieved green semiconductor laser diodes using semipolar GaN-based materials. The nonpolar/semipolar GaN-based materials are key in obtaining high efficient blue and green laser diodes.
Dr. Nakamura has received many awards, including: the Nishina Memorial Award (1996), the MRS Medal Award (1997), the IEEE Jack A. Morton Award, the British Rank Prize (1998), and the Benjamin Franklin Medal Award (2002). He was elected to the U.S. National Academy of Engineering in 2003. He received the Millennium Technology Prize in 2006. In 2008, he received the Asturias Award from Spain. He received the Harvey Prize of Israel Institute of Technology in 2010. He holds more than 100 patents and has published more than 450 papers in this field.