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It is a privilege for me to represent my colleagues here at the podium tonight. We want to thank the NAE and everyone connected with the Draper Prize for honoring us with this amazing award. We also thank our wives and families who have tolerated our absence over many years while we have been out chasing photons of various colors. We also want to thank our co-workers. Much of the work we have done, in fact nearly all of the work of this type, is done by teams. Without our co-workers this work would not have been possible. We are sorry that professors Akasaki and Holonyak could not be with us tonight. Professor Dupuis and i were both students of professor Holonyak, at the University of Illinois, who earlier had been a student of the great john bardeen, also at the University of Illinois.
The demonstration by Holonyak in 1962 that red leds and lasers could be fabricated from compound semiconductor alloys drove the solid state lighting revolution. It was the beginning. All of today’s high performance leds are compound semiconductor alloys. Holonyak also predicted in 1963 that his work would lead to solid state lighting, but that much more experimental work would be needed. That additional work has taken over fifty years and is still going. The work has taken many forms including working with new semiconductor alloys to achieve different colors, and growing increasingly complex semiconductor structures to improve efficiency. Nanometer scale layers and quantum wells were used by led engineers long before “nanotechnology” became a popular buzzword.
My contribution, working with others, was to pioneer the yellow led and to improve the efficiency of red and yellow devices. Professor Dupuis developed MOCVD the growth technology that is used for the production of all types of leds. Professors Akasaki and Nakamura developed high efficiency blue leds. These blue leds when combined with yellow down converter phosphor yield white leds that provide solid state lighting. Professor Nakamura also developed the blue laser diode which is now finding applications in headlights.
Early leds were barley visible in a lighted room but today they are 1000 times more efficient and still getting brigher. This year the super bowl was illuminated by led floodlights. All of general illumination is changing to from conventional illumination to leds. Even in third world countries, leds combined with solar cells lengthen the day by providing illumination for school children and adults who previously had only fire.
Conventional lighting technology has lasted around 100 years. Solid state lighting is expected to last much, much longer. In fact, in an article in the American Journal of Physics in September 2000 Holoynak argued that leds are the ultimate lamp. There is no end in sight for solid state lighting. Thank you again for recognizing us for our contribution to this ongoing world wide engineering effort.
M. GEORGE CRAFORD
SOLID STATE LIGHTING FELLOW