PORTLAND, Ore. Nagoya University professor Isamu Akasaki, winner of the 2009 Kyoto Prize for Advanced Technology for his pioneering work on blue LEDs and lasers, will speak on his "Enchanted Journeys in Blue Light" at the Kyoto Prize Symposium in San Diego on Thursday, April 22.
In a lecture at San Diego State University, Akasaki will detail his nearly decade-long quest for the blue LED, an effort that culminated in his 1989 demonstration of the world's first p-n junction blue LEDs using gallium nitride (GaN).
That work opened the door to the blue LEDs and blue lasers that have vastly boosted the data storage capacity of optical media as well as created more environmentally friendly lighting products.
"A lot of researchers had been studying gallium nitride, but because their crystals were so impure they deemed success impossible, and one by one they eventually left the field," said Akasaki. "But I continued working with gallium nitride. One day, in my lab, I spied a very, very tiny crystal that was extremely clear and bright. That gave me the conviction that success was possible; I just had to find a way to grow crystals that were very, very pure."
Akasaki removed that tiny, pure gallium nitride crystal and placed it on a sapphire substrate to encourage its growth into a complete, perfect crystalline layer across the wafer, but lattice mismatch between the GaN and the sapphire foiled the attempt. The researcher labored for years, trying out various solutions, only to have his hopes repeatedly dashed.
"Then one day an idea came to me of adding a buffer layer between the sapphire and gallium nitride layers. That was the breakthrough I needed," said Akasaki. "I found that a buffer layer of aluminum nitride provided a flexible interface with the substrate on the bottom allowing me to grow beautiful perfect crystals of gallium nitride on top."
Akasaki's pioneering work on gallium nitride nucleation on sapphire substrates, along with his demonstration of p-type doping, resulted in the blue LEDs and blue lasers used today in everything from DVD players to solid-state lighting.
The Kyoto Prize recognizes global achievement in a number of disciplines, including science, engineering, philosophy and the arts. Its sponsor is the Inamori Foundation, established by Kazuo Inamori, who founded both Kyocera and KDDI Corp. The 2009 awards, announced in November, marked the 25th anniversary of the Kyoto Prize, which has honored 81 individuals, representing 13 nations, since its creation.
The United States boasts the highest number of Kyoto honorees (33), followed by Japan (13), the United Kingdom (12) and France (eight).