Trends
Shimei Semiconductor grows blue LED on silicon wafer
"Shimei Semiconductor Co. has developed a blue LED grown on a silicon wafer that it plans to make available by next April.
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Organic semiconductors make cheap, flexible photovoltaics and LEDs
Imagine T-shirts that light up, or a beach umbrella that collects solar energy to run a portable TV. How about really cheap solar collectors for the roof?
All this and more could come from cutting-edge research at Cornell that demonstrates a new type of organic semiconductor device which shows electroluminescence and acts as a photovoltaic cell.
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QD Vision chief technologist Seth Coe-Sullivan named top innovator by Tech Review Magazine: MIT journal honors 35 top scientific and technology innovators under the age of 35
WATERTOWN, MA, SQD Vision, Inc. announced that Cofounder and Chief Technologist Seth Coe-Sullivan has been recognized by Technology Review as one of the world’s Top Science and Technology Innovators under the age of 35 for his breakthrough work in quantum dot LED performance and manufacturing process technology. Read more »
Japanese scientists have proposed a solution to the puzzle of why blue light-emitting diodes are so bright
Despite huge commercial success, until now the reason for the unusual brightness has not been known. The material they are made from - indium gallium nitride - can only be fabricated to such a poor quality that it would not be expected to emit much light.
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Rensselaer researchers aim to close 'green gap' in LED technology
Troy, N.Y. - A team of researchers from Rensselaer Polytechnic Institute has received $1.8 million in federal funding to improve the energy efficiency of green light-emitting diodes (LEDs).
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Novel Nano-Etched Cavity Makes LEDs 7 Times Brighter
Researchers at the National Institute of Standards and Technology (NIST) have made semiconductor light-emitting diodes (LEDs) more than seven times brighter by etching nanoscale grooves in a surrounding cavity to guide scattered light in one direction.
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Paint-on semiconductor outperforms chips
Researchers at the University of Toronto have created a semiconductor device that outperforms today's conventional chips -- and they made it simply by painting a liquid onto a piece of glass.
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Photonics crystals improve LED efficiency
A 50% increase in efficiency is a significant stride toward being viable sources for solid-state lighting.
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Aluminum Nitride Light Emitting Diodes with the Shortest Wavelength towards Dioxin, PCB Decomposition Technology
Nippon Telegraph and Telephone Corporation (NTT) has observed light of 210-nm wavelength from aluminum nitride (AlN) light emitting diodes (LED).
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Method May Help Optimize Light-emitting Semiconductors
Physicists at JILA have demonstrated an ultrafast laser technique for "seeing" once-hidden electronic behavior in semiconductors, which eventually could be useful in more predictable design of optoelectronic devices, including semiconductor lasers and white light-emitting diodes.
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Electrical Considerations of LED Bulbs
Governments all over the world regulated the future use of the inefficient incandescent lamps. For example, the member states of the European Union agreed to a phasing out of incandescent lamps by 2012. The initial European-wide ban applies the first step to “nondirectional” light bulbs. The first types of bulbs to be banned are frosted (non-clear) bulbs and clear bulbs over 100 W, which will be phased out completely by September 2009. The power limit will be moved down to lower wattages, and the efficiency levels raised by the end of 2012.
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Microstructured Optics for LED Applications
Optics for use with Light Emitting Diodes are described. Microstructured optics are available and customizable for a wide variety of applications. A few of these will be touched on. A methodology of designing these optics and the photometrics of the typical technology is overviewed.
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High Quality GaN Substrates for Modern LED Technology
It is well known that modern III-nitride based technologies for light
emitting diode (LED) production include (as an initial inevitable step) the preparation of GaN templates. Such GaN templates are usually delivered on foreign substrates possessing high lattice mismatch with respect to GaN layers, e.g., sapphire or silicon carbide substrates. The growth of GaN layers on highly mismatched substrates occurs via the formation of 3D islands with their following coalescence [1]. Such growth mode results in an extremely high density of threading dislocations (TDs) up to 1010–1011 cm–2 in the layer interior [1]. These TDs are known as main sources for the deleterious performance of LEDs and
other GaN based electronic and optoelectronic devices [2]. Therefore there exists an ultimate necessity in the developing of effective and low-cost recipes for low TD density GaN template manufacturing.
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Measurement of LEDs
Various new types of light emitting diodes (LEDs) are being developed and introduced for general illumination and other applications, and there are increasing needs for accurate measurements of various optical parameters of LEDs. Traditional standard lamps do not meet the calibration needs for LED measurements as LEDs differ substantially from traditional lamps in terms of physical sizes, flux levels, spectra, and spatial intensity distributions.
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Off-Line LED Control Circuit
Resonant mode topologies offer many benefits over traditional buck, boost and flyback solutions. These include soft-switching, higher operating frequencies, higher power density and higher efficiency. Electronic ballast designs for fluorescent lighting applications have already been taking advantage of these benefits for many decades. Much can be learned from electronic ballast circuits and applied to LED driver circuits. This article compares the load requirements for fluorescent lamps and LEDs, explains the functionality of a new dimming electronic ballast control IC, and describes a new resonant mode control circuit for LEDs that uses the new IC. Experimental results of the new circuit are also presented and summarized to show final performance.
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Primary and Secondary Optic Materials - LED Luminaire Performance and Lifetime
Numerous articles have been published regarding the lifetime of Light Emitting Diode (LED) luminaires, however, the primary focus has typically been on the lifetime of the LED die itself. Given that the LED luminaire is a system, it is important to recognize all aspects of the system that can affect or limit lifetime.
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