| Shuji Nakamura |
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When I was at University of Florida, the doctorate students ridiculed me. I only had a master's degree at the time I went to University of Florida. The students in the laboratory asked me whether I wrote technical articles and I replied I had not written any articles. When I was in the company, the company prohibited me from writing any articles or from making speeches at academic conferences. When I said I did not write any articles and also did not have a doctorate degree, the students treated me like a technician. In the United States undergraduates are treated as technicians. In the US corporate researchers inevitably have a doctorate degree. At that time I had been unaware of this, so it annoyed me and I resolved that, on my return to Japan, I would write articles and get a doctorate degree. Japan has a unique system that we can obtain a doctorate degree without attending a course - instead you can apply for the degree with a doctoral thesis. In order to do this, I ignored the company's system, which prohibited the writing of articles, and I wrote and presented articles, as I didn't fear the sack.
As professors Akasaki and Amano explained earlier, there were two kinds of the materials: one was zinc selenide (ZnSe) and the other was gallium nitride (GaN). Many researchers throughout the world were researching ZnSe. In the research of GaN there were very few, and only Professors Akasaki and Amano were doing such research in Japan at that time. If one thought about which was easier to write articles about - ZnSe or GaN - then GaN was easier because many researchers were researching ZnSe, but very few researchers were looking at GaN. As I had no experience of writing articles, I thought if I selected ZnSe then I could not compete at writing articles. This was one reason why I selected GaN as a material. Firstly I bought the MOCVD equipment that was on the market at the time, and then I began to start the crystal growth of GaN. However when I used the commercially available equipment, I got absolutely terrible results. This is because, as Professor Amano explained earlier, it was necessary to add some modifications. As this was only my first experience, I had not done this.
I started this research at 1989. Professors Akasaki and Amano already had many years of experience. Professor Akasaki started this research in the 1970s and Professor Amano started it at the beginning of 1980s. As I was a newcomer I could not get any results. The price of the MOCVD equipment was 2 hundred million yen which made me feel pressure to get some results. So I began to modify the equipment in my own way, just like Professor Amano did. I continued making these modifications everyday for one and a half years. Usually I made the modifications in the morning, but when I could not make modifications in the morning I did them in the afternoon. And one and a half years later, it was summer of 1990, I invented Two-Flow MOCVD to work. When I used this to grow GaN crystals, I could get results superior to the data of Professors Akasaki and Amano, which had been the best in the world up until then. I was absolutely delighted. This was the first time in my life that I had produced "a world best," "a world first"c such kind of top data. At that time nobody in the company could understand what that was like.
Using the modified equipment I made various crystals one after the other and over a 2-3 month period I produced several "first in world" and "best in world" results. For example, the indium gallium nitride, that Professor Amano told us he had been unable to get, could be created simply. Furthermore, when I somewhat modified the structure of the LED devices, I could get an extremely bright light. I also made various other breakthroughs, including obtaining p-type GaN. In 1989 when I just started the research of GaN, Professors Akasaki and Amano presented their way of getting p-type GaN. At that time I was just starting the research, and I was shocked to hear it. As I had the intention to develop the first p-type GaN in the world, the success stumped me. So I checked the article on getting p-type GaN and realized that p-type GaN was being obtained by irradiation with electron beams. I actually started trying to get p-type GaN in 1991 and I presented an article in 1992. I had succeeded in getting p-type GaN simply by heat treatment. Once again it was the quality of the equipment that had allowed me to produce such good quality p-type GaN.
The 2-flow MOCVD was built in summer of 1990, and after that I got good data within a few months. The invention of the Two-flow MOCVD is covered by patent 404, ownership of which is now being disputed with my former company under the patent law. By using this patent my former company got good results: a blue LED that emitted strong light and a good laser diode.
I applied for this patent promptly. As I explained earlier, the company prohibited publishing articles and speaking at academic conferences. Even applications for patent types that were subject to public disclosure were prohibited. All patent applications were limited to "know-how" applications (not made public by the patent office). As I explained earlier I wanted to submit articles. After I succeeded with Two-Flow MOCVD, I submitted the articles in secret. Before submitting the articles, I made patent applications as a way of covering my back once the articles were publicized. Writing the articles was the incentive for pursuing my research, and before publishing them I always made confidential patent applications. Thanks to these patents, my former company is doing well. They have used the patents to sue many rival firms. The have even made a claim against me. This claim in the united state resulted recently in my winning, which I am very happy about.
After all this, I succeeded in commercializing the blue LED in 1993. This device emitted bright light of which the intensity was more than 100 times brighter than previous devices. When this device was announced, no one believed it immediately, but people who tested the device practically were surprised. I also developed and announced the commercialization of green LED in 1995. I achieved the first laser oscillation in late 1995 and succeeded in the commercialization of the blue laser in about 1999. In the meantime I made several hundred patent applications and about 50 important patents were granted which produced profits for my former company.
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