High brightness blue light-emitting diode development (three): with frustrated return home, everything from scratch, busy all day equipment transformation

This is the third story of the development of high brightness blue light-emitting diode. Part one tells the developer Nakamura Shuji from entering the Nichia chemical industries to select blue LEDs as the process of this research. This article will continue to tell the story of the village from the beginning to study the successful selection of the GaN material to grow a crystal film story. In order to study the blue light-emitting diode, we must master the crystal growth technology of the luminescent layer. To this end, the village went to the United States to study, but in the United States is a waste of manufacturing equipment for a year. After returning home he continued to manufacture and transform the device. After a long and arduous efforts, and finally achieved initial results......

In March 1988, Nakamura Shuji was in a state of excitement and boarded a flight to florida. He will study as a researcher at the University of Florida (University of Florida) for one year (Table 1).

Table 1: development of blue led.

Visit to the United States as an opportunity to study, from the village to visit the The University of Tokushima alumni Sakai Shiro (now The University of Tokushima Professor) conversation. To make a blue light-emitting diode, it is necessary to form a single crystal film for the blue light-emitting diode. The techniques include MBE (molecular beam epitaxy, molecular Shu Waiyan) injection 1 and MOCVD (metal organic chemical vapor deposition, metalorganic chemical vapor deposition) Note 2). Nakamura did not hesitate to choose the MOCVD method. The reason is that the price of MBE devices up to hundreds of millions of yen, the company simply can not consider the purchase.

Note 1) MBE (molecular beam epitaxy) is a method of growing a single crystal film on a substrate, which belongs to a vapor phase growth method. In the control of the atomic (molecular) beam which is introduced into the real air, the substrate is irradiated to make the atomic deposition. High precision vacuum deposition technology. The use of this technology is required when making components of silicon and GaAs compound semiconductors.

Note 2) MOCVD (metal organic vapor deposition) method is a kind of CVD (chemical vapor deposition, chemical deposition) method for depositing thin films on the substrate. Also known as OMCVD (organometal CVD) method. CVD is a gas containing sediment, mixed gas or the gas and non reactive gases pass into the bottom after heating, the thermal decomposition, oxidation reduction and replacement of chemical reaction method to generate on the floor or deposit needed material. Among them, the raw material gas using organic metal (organic matter directly with the metal compound, organometal) method is called MOCVD method. This technique is widely used in the growth of GaAs and other compound semiconductor single crystal films on the substrate.

Although the choice of the MOCVD method, but the village is the first contact with this technology. So first need to learn. He decided to study the law of the MOCVD famous Sakai Nori. Sakai Mi decided to go to florida. He suggested that the village, "rare opportunity to go together". This is a good opportunity to wish for, but I do not know whether the company would send to.

The company will not agree, the first application to the company again. Holding this mentality, the village decided to try. So he asked Sakai accompanied to the president and the president explained his ideas. Surprisingly, the company decided to send him to florida.

Back to the previous state

Everything can run in both directions unblockedly! Let a person feel smooth as if in a dream. But the University of Florida after the good times don't last long, arrived in the village was very surprised, there is no MOCVD device, and imagine different.

The study room in the village should have 2 MOCVD devices. One of them was moved out of the next lab, and the other one needed to be manufactured from now on. So in the United States, the village also began to work for manufacturing equipment (Figure 1). Every day, busy with piping and welding, and in Japan, there is no two. He can not help but think that oneself is to do the work all the way to Florida? And then there's a sense of burnout. Time is not in the mood to pass in the village mercilessly. Wait until the middle of the village is not easy to complete the production of the device, it has been a month before he came back.

Figure 1: when the village in the United States made the MOCVD device in the village of Florida in the fall of 1994, when visiting Florida, with the installation of this device is still running

In addition to the village, there were several researchers from South Korea and China and other countries. In the village with a smiling face begged: I have to go back to Japan after a month, time is very tight, the device can let me give priority to use. The answer is No!. In the village of only 3, the 4 crystal growth experiment, it is necessary to study in the United States drew a full stop.

Not even a meeting

I do not know is poor in the village, or fancy the village of excellent welding and plumbing technology, Professor of the laboratory to retain him: I give you wages, to stay for a year". But in the United States, to the village left too many unhappy memories.

Before the village to the United States did not write a paper. Because the company is not allowed. It is for this reason, it is not easy to go to the United States as a researcher, the other did not treat him as a researcher, even the meeting did not inform him. The university has led research personnel, but in the village to ask questions, people indifferent.

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