24 Aug 2006
Kyma adopts a novel approach to developing new green LEDs for a US Department of Energy funded R&D program.
Kyma Technologies, Raleigh, NC, is to develop a novel type of green LED in a project funded under the US Department of Energy's Solid State Lighting Core Technologies Program.
Kyma's proposal (which won a recent competition for the funding) is entitled High Performance Green LEDs by Homoepitaxial MOVPE, co-led by Professors Christian Wetzel and E. Fred Schubert of Rensselaer Polytechnic Institute, of Troy, NY.
The development team plans to fill the so-called "green gap" in current semiconductor LED technology by developing improved materials and processes for making green LEDs based on the III-nitride materials family.
Key materials improvements are expected to arise from use of Kyma's low defect density native gallium nitride substrates. Such materials and process improvements would need to be realized to capitalize on the solid state lighting market opportunity, generally considered to be the largest nitride semiconductor device potential market.
Wetzel is Rensselaer's Wellfleet Career Development Constellation Professor of the Future Chips Constellation and Schubert is Rensselaer's Wellfleet Senior Distinguished Professor of the Future Chips Constellation. Kyma's Principal Investigator on this effort is Drew Hanser, the company's co-founder and CTO.
According to market analyst Strategies Unlimited, the worldwide commercial market for nitride semiconductor devices reached $3.2 billion in 2004 and is expected to grow to $7.2 billion in 2009.
Under the program, Kyma will continue to develop its patented native crystalline GaN materials manufacturing technology and will also provide both polar and non-polar native GaN substrates to the Rensselaer researchers for epitaxial growth, device fabrication and device performance testing.
The addition of native non-polar GaN substrates to Kyma's product line was announced earlier this year and represents the highest quality non-polar GaN that is commercially available today.
Many experts in the field of nitride semiconductor materials and devices, including Shuji Nakamura at University College of Santa Barbara, have touted the potential of non-polar GaN to enable commercially significant LED performance improvements.
However, the efficiency of initial devices made from non-polar GaN-based materials has so far been limited by the presence of defects which result from a non-native fabrication approach. Use of Kyma's native GaN substrates should enable reduction of such defects by a factor of over 10,000 compared to such non-native approaches, the company claims.
"While much progress has been made in developing blue and green LEDs on sapphire and silicon carbide substrates, much more progress is required, especially in the green, before nitride LEDs can begin to realize their full commercialization potential," said Kyma's Drew Hanser.
"We believe that our native GaN substrates have the potential to enable the development of green LEDs with the kind of price point and operating characteristics that fulfill the promise of solid state lighting for general illumination."
About Solid State Lighting
Dramatic changes are unfolding in lighting technology. Semiconductor LEDs, until recently used mainly as simple indicator lamps in electronics and toys, have begun to replace incandescent bulbs in many applications, particularly those requiring durability, compactness, cool operation and/or directionality (e.g., traffic, automotive, display, and architectural directed-area lighting).
Further major improvements are believed achievable. Electrical-to-optical energy conversion efficiencies over 50% have been achieved in infrared light emitting devices. If similar efficiencies were achieved in visible light emitting devices, the result would be a 150-200 lm/W white light source two times more efficient than fluorescent lamps, and ten times more efficient than incandescent lamps.
About Kyma Technologies
Kyma was co-founded in 1998 by researchers at North Carolina State University. The company develops high quality bulk GaN-based substrates and epiwafers to device manufacturers in both electronic and optical markets, and its mission is to become the preferred supplier of native nitride substrate based materials and device solutions. Kyma has developed a strong IP portfolio including exclusively licensed NCSU patents and its own patented and patent-pending technologies.