'Slave' Nakamura fights for his rights

17 Jun 2002

If blue laser-diode inventor Shuji Nakamura wins his patent dispute with his former employer, Nichia, it could be good news for the optoelectronics industry. He tells Rebecca Pool about the dispute, his research and why he left Japan to work in the US.

From Opto & Laser Europe May 2002

In 1989 Shuji Nakamura was one of many scientists who were trying to develop a blue laser-diode. However, unlike his contemporaries, Nakamura was working on a semiconductor called gallium nitride. Some 13 years later he is locked in a bitter patent dispute with Nichia and stands to receive an estimated EURO 17 m if he wins. Why? Because he was first past the post.

Nakamura demonstrated efficient room-temperature blue-laser emission from indium gallium nitride-based diodes in 1995, when he was working at Japan-based firm Nichia Chemical Industries. The circumstances that led him to this breakthrough are perhaps surprising. "In 1989 I started blue LED research on GaN because at the time I hated the thought of following the big companies and what they were doing," said Nakamura. "I knew I couldn't beat them using the same materials [GaAs and gallium phosphide] so I chose GaN. I never expected to succeed but I tried anyway, out of desperation."

And although it is now clear that his efforts were worthwhile, the past two decades have not been easy for Nakamura. He first started working for Nichia in 1979, developing infrared and red LEDs. Despite some success, Nichia was late in marketing developments and in 1988 Nakamura decided to switch to blue LEDs.

Before starting his blue LED work, Nakamura spent a year at the University of Florida in the US. During that time he learned about metal organic chemical vapour deposition (MOCVD) - the technique used, in this instance, to deposit InGaN thin films onto sapphire substrates. Nakamura also experienced first-hand what he calls "the American freedom".

"When I was in Florida for that year, I enjoyed the American freedom," he said. "I found the professors more collaborative, friendly and helpful, and compared with Japan there was no bureaucracy at all. When I left, I envied the Americans."

Once he was back at Nichia, however, Nakamura started his GaN-based blue laser-diode work, and by 1992 he had developed a novel MOCVD method. Unlike MOCVD techniques of the time, this method used two separate gas flows, one to carry the reactant gas parallel to the substrate and a second to transport an inactive gas perpendicular to the substrate. The inactive gas-flow then changes the direction of the reactant gas, forcing it to make contact with the substrate. By tweaking technique parameters such as gas-flow and temperature, Nakamura could alter the amount of indium deposited onto the substrate to generate 3D localized electron energy states. These localized states were found to be responsible for strong light emission in InGaN and by 1995 Nakamura had achieved blue laser emission from his III-V nitrides.

Although when taken on their own these research breakthroughs are striking, they could be considered outstanding in the context of the research conditions under which Nakamura was working at the time.

"In 1990 and 1991, the president [of Nichia] asked me to stop the GaN research immediately," said Nakamura. "At this time Nichia had no desire to investigate blue LEDs, so they asked me to work on GaAs high-electron mobility transistors (HEMT) instead. I ignored them."

While pursuing his research at Nichia, Nakamura is reported to have received no technological support, other than his research and development budget. Nichia is also said to have banned its researchers from publishing their work at this time.

"I couldn't get money from the company [Nichia] and I couldn't get money from the government when I submitted a proposal. That was tough," said Nakamura.

So after 20 years of service at Nichia, having achieved his goal of efficient lasing from blue diodes, Nakamura, otherwise known as "Slave Nakamura" by his US contemporaries, left Japanese industry for a life in academia at the US-based University of California Santa Barbara (UCSB).

Today Nakamura is the director of the Solid State Lighting and Display Center at UCSB. The centre has recently received funds of $12 m (EURO 14 m) from five companies, including semiconductor and LED makers Rohm of Japan and Cree of the US.

Currently putting the finishing touches to his new laboratory, Nakamura says that his blue LED and laser-diode work is complete and he now plans to investigate a number of new avenues. "I will study solid-state lighting: using GaN we can make high-brightness white lighting," said Nakamura. "I would like to replace all conventional vacuum-tube lighting, including incandescent bulbs and fluorescent lamps. This will save energy and resources, which is very important."

He also intends to investigate ultraviolet LEDs and laser diodes for biochemical detector applications and high-power GaN-based microwave devices for wireless infrastructure and satellite communications. As well as his research, Nakamura is also now responsible for teaching students at UCSB. "Teaching is very tough because I have to prepare lots of things for it, but I am enjoying it," he said.

Ask Nakamura what else he enjoys about his new life in the US and he is quick to highlight the contrasts between his life as a researcher in Japan and his current position. "I enjoy a lot of freedom here in the US. This country and Europe are very democratic," he said. "Japan is a bit of a communist country and has a very bureaucratic system compared with the US and European countries. And there is no co-operation between professors."

But why did Nakamura leave industry for academia? The answer is quite simple: to avoid being sued by Nichia. "I first wanted to move into industry [in the US] to focus only on research. At a university I knew I would have to do teaching as well - although I am enjoying it a lot now," he explains. "But at the time I had the problem that Nichia would sue me if I joined industry, so I went to a university."

Nakamura's tactic was unsuccessful, however. In December 2000 Nichia filed a lawsuit against him anyway, which he says included accusations that he had infringed the company's trade secrets. Other reports suggest that Nichia was worried that its former employee would disclose confidential information to UCSB and organizations such as Cree.

Nakamura, frustrated at his inability to publish Nichia-related work, filed a lawsuit against Nichia in the Tokyo District Court in August 2001 claiming partial patent rights to his work and ¥2 bn (EURO 1.7 m) in compensation. While this move has startled lawyers and researchers alike, Nakamura is pragmatic about the situation.

"I decided to take action against Nichia because in Japan there is a special patent law that exists only there and in Germany," he explained. "Even if a researcher invents a patent at a company, using company money and company people, the patent belongs to the inventor, not the company."

Nakamura says that a legal decision concerning the patent ownership will be made this month, and he hopes the courts will make a decision about the compensation by the end of this year. And if he wins?

"I want to license [this technology] to all companies. Nichia won't license the technology to anyone else, but I would license to everyone," he said.Such a move would make life easier for blue laser-diode makers worldwide. Take the latest violet laser-based DVD standard set by nine consumer electronics companies in February this year. Although Nakamura is excited because the technology is based on his invention, he is also sceptical about the likely success of the group. At the moment, Nichia is the only company that is able to make blue laser-diodes.

"[In the current situation] only Nichia can supply all the demand," said Nakamura. "If next year all of the DVD companies start to sell next-generation DVDs, Nichia will not be able to cover the demand."

As well as his reservations about Nichia's present monopoly, Nakamura is also concerned about the high cost of today's blue laser-diodes. While he acknowledges that his own work on the diodes is finished, he is adamant that a materials breakthrough - namely developing a GaN substrate - is crucial to lower these prices.

Nakamura believes, however, that companies such as Germany-based Osram Opto Semiconductors have already "done well" to develop a cheaper blue laser-diode, and their work could pave the way to even cheaper diodes. Although it has not used a GaN substrate, Osram has developed a InGaN blue laser-diode on a SiC substrate.

Nakamura is also confident that Nichia's patent actions will not hamper the research of companies like Osram. "We still have to develop a breakthrough to reduce the cost of the laser diode and companies like Osram can develop a new technology with a new intellectual partner," he said. "We have to tackle a lot of problems but I think that because today's prices are so high, Nichia cannot dominate this sphere."

So apart from making what is perhaps one of the optics industry's most important breakthroughs, writing his autobiography, launching a multi-million dollar laboratory and being caught up in one of the technology world's most contentious patent disputes, what else has Nakamura done lately?

Not surprisingly, the awards have been flooding in. Nakamura has recently won the IEEE Jack A Morton award for outstanding contributions to solid-state devices, the British Rank prize for significant advances in optoelectronics and the Julius-Springer prize for outstanding and innovative contribution to applied physics.

This year, standing alongside such greats as Max Planck, Albert Einstein and Stephen Hawking, Nakamura has won the Benjamin Franklin medal and is now tipped to receive a Nobel prize. Not bad for someone who didn't expect to succeed.