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Green
light on blue light
Blue light technology remains BU’s intellectual property
By Tim Stoddard
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 BU’s gallium nitride patents.
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| In the late 1980s, photonics pioneer Theodore Moustakas discovered a way to make a highly sought-after substance called gallium nitride, which is now ubiquitous in blue light-emitting diodes and blue light lasers. That patented process was at the heart of an intellectual property rights dispute between the University and Nichia Corporation of Japan. Photo by Vernon Doucette |
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On November 13, 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 BU’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 machines. 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 a two-step process,
called the buffer-layer 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 years 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 the 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, 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’ 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 over 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, 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 tell-tale
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 BU’s Photonics Center 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 go into their blue
period.
13 December 2002
Boston University
Office of University Relations