Technology | Dec 18, 2006

UC Santa Barbara Researchers Set New Records in Energy Efficient Light Emitting Diodes

Santa Barbara, California USA-- Researchers at UC Santa Barbaras Solid State Lighting & Display Center and the Japan Science & Technology Agencys Exploratory Research for Advanced Technology program (JST ERATO) have set new records for nonpolar and semipolar light emitting diode (LED) efficiency.

This new class of gallium nitride-based LEDs is based on new nonpolar and semipolar orientations of GaN with record external quantum efficiencies, and they exhibit polarized light emission.

The new non-polar LEDs have an external quantum efficiency of 41% and radiant powers as high as 25 mW for standard sizes (300 µm x 300 µm) and operating current (20 mA). The semipolar LEDs exhibited external quantum efficiency of 30% and radiant powers as high as 18 mW, also for standard chip sizes and operating current (20 mA). The polarized light emission will enable a new class of light sources and will be useful in applications such as LCD backlighting. Dr. DenBaars stated that these recent achievements in high power nonpolar LEDs represent almost an order of magnitude improvement in efficiency and brightness over previous reports.

The groups led by Shuji Nakamura, Steve DenBaars and James Speck -- all professors of materials -- have also achieved c-plane LEDs with external quantum efficiencies of 66%. These LEDs have been used to make white LED lamps which boast a luminous efficacy of 116 lm/W  more efficient than both incandescent bulbs and fluorescence lamps. Dr. Nakamura commented on the improved efficiency, saying that these results further confirm that white LEDs could save billions of dollars in energy costs and help reduce greenhouse gases associated with electricity production.

The commercial applications of nonpolar LEDs include LCD backlighting, projections televisions, medical imaging and general illumination. Dr. Speck noted that these results "...validate our premise that nonpolar GaN would enable commercially viable high performance GaN light emitting devices."

Research funding was provided by the Solid State Lighting & Display Center and by JST ERATO. UCSBs Solid State Lighting & Display Center, www. ssldc.ucsb.edu, is focused on advancing new semiconductor-based energy efficient lighting and display technologies through partnerships with key industry leaders.

Engineering at UC Santa Barbara: Engineering at UC Santa Barbara is considered a leader in bioengineering, chemical and computational engineering, materials science, nanotechnology, optics and physics. UCSB has five faculty Nobel Laureates and one Millennium Technology Laureate. The College of Engineering uniquely successful interdisciplinary and entrepreneurial approach to research and learning is central to these achievements. www.engineering.ucsb.edu

Add comment

You can add a comment by filling out the form below. Plain text formatting. Comments are moderated.

Question: What is 1 + 3 ?
Your answer:
FEATURED

Luxeon V2, the Best Choice for a 2 mm² High Power LED

Luxeon V2, the Best Choice for a 2 mm² High Power LED Lumileds announced breakthrough high power performance with the new Luxeon V2 LED. With the highest performance in its class for output and efficacy, the emitter easily enables DLC Premium performance at the system level. Luxeon V2 utilizes a 2 x 2 mm Chip Scale Package (CSP) in a 3.5 x 3.5 mm ... Read more »

FEATURED

The 22nd China (Guzhen) International Lighting Fair

The 22nd China (Guzhen) International Lighting Fair China (Guzhen) International Lighting Fair is based in China Lighting Capital- Guzhen Town, where thousands of lighting manufacturers lies and is dubbed as the source of lightings. With the help of local government and UBM, the fair has been successfully held for 21 editions. Read more »

EDITORIAL

High Conductive Foils Enabling Large Area Lighting

High Conductive Foils Enabling Large Area Lighting Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP as one of the leading partners for research and development for surface technologies and organic electronics and Sefar AG, a leading manufacturer of precision fabrics from monofilaments, developed a roll-to-roll ... Read more »

page_peel