“Walking alone in the wasteland” Nobel Prize won with indomitable spirit

我ひとり荒野を行く ―不屈の精神がもたらしたノーベル賞―


“We produced blue light-emitting diodes on our own for the first time in the world in 1989. I will never forget that eye-opening cobalt blue light throughout my life.”



This is a passage from an autobiography written in 2013 by Dr. Isamu Akasaki, a ten­ured professor of Meijo University and one of the three recipients of the 2014 Nobel Prize for Physics. The book, pub­lished by Nikkei Pub­lishing Inc., is titled “Fascinated by blue light - A story of blue LED”. A copy of the book has been donated to Hakumon Herald by the university. It tells about the long, rugged road the author trod to reach his ultimate goal, the invention of blue LEDs seen sure lighten the world in the 21st century.

これは、今年のノーベル物理学賞に輝いた3人の日本人学者の1人、赤﨑勇名城大学教授(83)が2013年に表わした本「青い光に魅せられて 青色LED開発物語」(日本経済新聞出版社刊)の一節だ。赤﨑教授が在籍する名城大学より寄贈してもらったこの著書をもとに、21世紀を灯す光と言われるようになった青色LED発明までの苦難の道のりをたどってみた。


  LED is a semiconductor, a substance known to exist halfway between a conductor that transmits electric current well and an insulant that doesn’t. It emits light by transforming electron energy into light energy. The color of the light changes in accordance with the power of energy applied to electron. Red light is generated by a weak power and blue light by a strong power. In other words, a semiconductor crystal with strong energy has to be developed to produce blue LEDs.



Dr. Akasaki had fought a lonely hard battle before succeeding in developing such semiconductor in 1989. He writes in his autobiography, “I felt as if I were walking alone in the wasteland." LED was touted as a lighting device of the next generation but scientists had been unanimous that “the development of any practical blue LED won’t come before the end of the 20th century”.



  When Dr. Akasaki began his work in 1973, three materials were considered promising in the development of a blue luminescent device. Those were silicon carbide, zinc selenide and gallium nitride (GaN). He chose GaN. But most scientists in those days based their work on materials other than GaN, which was known to be quite “tough”. The word usually has two meanings: (1) strong, rigid or stout and (2) difficult or troublesome.



Any material fit for a blue luminescent device must be tough in the former sense. However, the tougher it is, the more difficult will it be to process it. Diamond may be a good example to explain that. Diamond becomes a beautiful crystal only under the condition of a high pressure up to 52,000  atm and a high temperature of about 1,200 degrees C in the earth’s crust. A man-made diamond is less brilliant than a natural one because such condition cannot be artificially produced.


GaN crystallizes under a much tougher condition of more than atm and 2,500 degrees C. Moreover, while diamond exists in the natural world, GaN doesn’t. For these reasons, many researchers gave up GaN or shifted their study to other materials in the late 70s. When Dr. Akasaki produced papers on GaN, no one cared to read them.



 However, he devoted himself to his study and finally succeeded in producing a GaN crystal decent enough in size and thickness, using the MOVPE (metal-organic vapor phase epitaxy) method. Looking back at that time, he writes in his book:


“While I was observing my wafer (a crystallized plate) full of pits and cracks through a fluorescence microscope, I found beautiful minute crystals albeit only rarely.



  “I looked at them closely. They were gleaming out brilliantly. Then I felt GaN has the great possibility as a material for a blue luminescent device.



  “Then an idea struck me that if I can upgrade the quality of the entire wafer to that of those beautiful minute crystals, I might be able to attain electrical conduction control (p-type conduction).



  “Convinced this way that ‘crystal growth holds the key’, I decided to get back once again to ‘crystal growth’ which was the starting point of my study.



  “I think it was a ‘crossroads’ not only for my research and development of GaN-based blue luminescent devices but also for similar researches going on in other parts of the world.”


In 1985, Dr. Akasaki succeeded in producing a high-quality GaN single crystal. After breaking through the highest barrier of his study, he succeeded in making blue LEDs in 1989. The passage introduced at the beginning of this article is full of the deep emotions the author felt at the moment 16 years of his painstaking efforts bore fruit.



Dr. Akasaki says in his book, “Just do what you want to do was the words I inherited from my father.” He could continue what everyone thought impossible because he strongly felt he was doing his favorite thing. You may finally make it if you pick your favorite and hold on to it. Indeed it was Dr. Akasaki’s unyielding spirit that brought him his Nobel Prize.


(Written by: Yuxi Luo)