By Tim Stoddard

Photonics pioneer Theodore Moustakas.

After months of legal wrangling with a Japanese technology company, Boston University has reached a favorable settlement in its first patent-infringement lawsuit. The dispute between the University and Nichia Corporation centered around BU's 1997 patent on a process for synthesizing gallium nitride, a semiconductor that is now widely used in blue light-emitting diodes (LEDs).

Blue LEDs and blue-light lasers are poised to revolutionize everything from DVDs to cell phones to Thomas Edison's bright idea, the light bulb. But until now, the future of this technology has been clouded by a legal fracas between Nichia and Cree Lighting, Inc., a North Carolina company that has exclusively licensed some of Boston University's gallium-nitride patents.

On November 13, 2002, Cree and Nichia announced a settlement of all litigation, including the suit concerning BU's patents. The financial terms of the settlement were not disclosed, but Ashley Stevens, director of technology transfer at BU's Community Technology Fund, says that the outcome was favorable for the University. The upshot of the agreement, he says, is that Boston University's patent will now be sublicensed to Nichia and possibly to other companies that manufacture blue LED devices.

Considering the size of the blue LED market, these sublicenses have the potential to be very lucrative for the University. Blue laser diodes, which are based upon blue LEDs, are a key component in the next generation of DVD devices, which will be able to store about five times more digital data on a disc than current DVD machines store. Earlier this year, nine leading electronics companies, including Sony, Pioneer, Sharp, and Hitachi, announced standards for the next-generation DVD format, called Blu-ray Disc. And within five years, blue LEDs are expected to replace the energy-wasteful incandescent light bulbs in homes and businesses.

Kind of Blue

LEDs appeared about 40 years ago when researchers first figured out how to squeeze light out of semiconductor crystals. When electricity flows through these crystals, they emit photons of light at a certain wavelength, depending on the composition of the crystal. Early LEDs were made with a compound called gallium arsenide, and they produced only weak red and green glows suitable for clock and calculator displays. But about a decade ago, engineers invented a crystal made of aluminum gallium indium phosphide that produced a brighter red light.

Around the same time, LED pioneer Theodore Moustakas, an ENG professor of electrical and computer engineering, who works at BU's Photonics Center, discovered a technique for making gallium nitride, a highly sought after semiconductor that yields blue light. Moustakas developed the buffer-layer process, a two-step process for depositing gallium and nitrogen atoms onto silicon, sapphire, and other substrates. To this day, it remains the only known way to make blue LEDs.

As Moustakas was reporting his early successes with gallium nitride, Shuji Nakamura, an engineer at Nichia, was racing to perfect the technique as well. In August of 1991, Moustakas published a paper detailing the buffer-layer process; several months later, Nakamura published similar results in a different journal. But it was Nakamura who went on to build the first working blue LED, and "most people in the field now credit him with discovering the process," Moustakas says. Through the course of the recent lawsuit with Nichia, however, Moustakas was able to prove that he and Boston University were, in fact, the first ones to come up with the buffer-layer technique.

Commercializing that patent required lots of careful planning. For the last seven years, George Rabstejnek, an investment consultant with extensive experience in transferring intellectual property into the private sector, has helped Moustakas and the Photonics Center explore dozens of companies interested in gallium-nitride technology. Last year, the Community Technology Fund licensed the buffer-layer patent to Cree, which sells LEDs to customers who incorporate them in full-color displays in cell phones, personal digital assistants (PDAs), video boards in stadiums and arenas, and traffic lights. Soon thereafter, Nichia alleged that Cree was involved in trade-secret theft. Cree and Boston University then jointly sued Nichia for infringing on the Moustakas buffer-layer patent. On November 13, 2002, the companies entered into a patent cross-license agreement and a settlement of all litigation.

"We are pleased that this litigation has been settled," says Stevens. "It appears that Nichia recognized that it needs a license to the buffer-layer patent that resulted from Moustakas's pioneering work, and Cree will be offering sublicenses to the buffer-layer patent to the other manufacturers of gallium-nitride devices."

"This settlement represents an important step forward for Cree, Nichia, and the entire nitride optoelectronic industry," says Chuck Swoboda, Cree's president and CEO. "This agreement should allow us to focus more of our resources on developing products to support the growing demand for blue, green, and white LEDs."
Ownership of the buffer-layer patent is important as well because it is an essential step in building blue laser diodes, which will power the next generation of optical- data-storage devices.

To make this type of laser, engineers place mirrors near a blue LED to amplify its light (the word laser is an acronym for light amplification by stimulated emission of radiation) so that all the photons are aligned in the same direction. For more than a decade, tiny red and infrared laser diodes have been used to read and write digital information onto CDs and DVDs. Because the wavelength of blue light is shorter than that of red light, blue lasers can focus a beam onto a smaller area of disc, encoding about five times more information in the same amount of space. In a few years, DVD recording systems should be able to etch 13 hours of video, which equates to more than six full-length movies, onto discs the size of standard CDs.

Greener Light

An even more important application of blue LEDs, Moustakas says, will be in supplanting the incandescent light bulb. High-intensity color LEDs are already in widespread use across the United States.

The telltale dots of red, yellow, and green now light up half a million traffic signals across the country, and instead of having to be replaced annually like their standard incandescent counterparts, the LED signals should last 5 to 10 years. They use 80 to 90 percent less electricity than conventional signals, thus saving at least 400 million kilowatt-hours a year in the United States. LEDs are far more energy-efficient than incandescent bulbs. Today's LEDs convert about 30 percent of the energy in electricity into light, Moustakas says, while standard incandescent bulbs convert only between 3 and 5 percent of that energy into light, giving off the rest as heat.

"Then you have to waste even more electricity in air conditioners and fans to carry that heat out," he adds. Theoretically, LEDs could reach efficiencies of 99 percent, and replacing incandescent bulbs with them, Moustakas says, would lead to an anticipated $60 billion in energy savings a year nationally.

As scientists at the College of Engineering and the Photonics Center at Boston University develop ways of building white-light LEDs, Moustakas continues to work on a new class of electronics devices that will use the buffer-layer patent. He is developing gallium-nitride transistors for high-temperature and high-power applications. "At the moment, we simply do not have any other semiconductors that we can use in these conditions," he says.

For instance, the automotive industry is keen on developing high-temperature transistors that can be placed directly onto an engine block to monitor various combustion processes. Current silicon-based transistors can't do this because silicon becomes metal-like at 100 degrees Celsius, losing its semiconductor properties. In 1994, Moustakas developed the first transistor that could function at up to 530 degrees Celsius.

Other applications of gallium nitride are in the works as well. And with BU's intellectual property rights secured, Moustakas and his colleagues are eager to help electronics and lighting companies move into their blue period.