Trends

Technology | Nov 16, 2006

Shimei Semiconductor grows blue LED on silicon wafer

shimei-gif "Shimei Semiconductor Co. has developed a blue LED grown on a silicon wafer that it plans to make available by next April. Read more »

Technology | Oct 27, 2006

Organic semiconductors make cheap, flexible photovoltaics and LEDs

Schematic of a junction between two organic semiconductors, an anthracene derivative containing free positive ions and a ruthenium, complex containing negative ions. When the two are joined, ions diffuse across. 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. Read more »

Technology | Sep 26, 2006

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 »

Technology | Sep 06, 2006

Japanese scientists have proposed a solution to the puzzle of why blue light-emitting diodes are so bright

bright-20blue-20led-gif 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. Read more »

Technology | Aug 25, 2006

Rensselaer researchers aim to close 'green gap' in LED technology

greenled_b-jpg 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). Read more »

Technology | Jul 27, 2006

Novel Nano-Etched Cavity Makes LEDs 7 Times Brighter

Etched nanostructured rings around an LED can make it more than seven times brighter. The novel technique developed at NIST may have applications in areas such as in biomedical imaging where LED brightness is crucial. 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. Read more »

Technology | Jul 18, 2006

Paint-on semiconductor outperforms chips

Paint-on semiconductor ( Image from Ted Sargent) 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. Read more »

Technology | Jun 01, 2006

Photonics crystals improve LED efficiency

Figure 1 A 50% increase in efficiency is a significant stride toward being viable sources for solid-state lighting. Read more »

Technology | May 17, 2006

Aluminum Nitride Light Emitting Diodes with the Shortest Wavelength towards Dioxin, PCB Decomposition Technology

Figure1 Aluminum Nitride, "Shortest Light-Emitting Semiconductor" Nippon Telegraph and Telephone Corporation (NTT) has observed light of 210-nm wavelength from aluminum nitride (AlN) light emitting diodes (LED). Read more »

Technology | Feb 16, 2006

Method May Help Optimize Light-emitting Semiconductors

What do you see in these Rorschach-blot-like images? JILA physicists see the once-hidden electronic behavior of semiconductors. The computer plots show how energy intensity (ranging from low in blue to high in red) varies as electronic structures called excitons absorb laser light and emit energy at various frequencies. The pair of similar "butterflies" indicates that an exciton is absorbing and emitting energy in a predictable pattern. 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. Read more »

Technology

Electrical Considerations of LED Bulbs

Figure 8: LED bulb with an isolated driving and feedback circuit. 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. Read more »

Technology

Microstructured Optics for LED Applications

Figure 1: Common types of optics. 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. Read more »

Technology

High Quality GaN Substrates for Modern LED Technology

Figure 3: AFM data illustrating the NI density for a) sample A and b) sample B. The overgrowth of sparse NIs can result in formation of new islands (c). Using increased reactor pressure the formation of new islands during HT overgrowth can be suppressed (d). All the scans are 10 μm × 10 μm. 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. Read more »

Technology

Measurement of LEDs

Figure 5: NIST gonio-spectroradiometer for the total spectral radiant flux scale realization 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. Read more »

Technology

Off-Line LED Control Circuit

Figure 1: Fluorescent dimming ballast block diagram 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. Read more »

Technology

Primary and Secondary Optic Materials - LED Luminaire Performance and Lifetime

Figure 1: LumiBright LE line of light engines for commercial applications and incorporating high efficiency primary optics, photosensor, and thermistor on a high thermal conductivity metal core PCB in one package. 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. Read more »

FEATURED

WHITE PAPER: Measuring UVA & Violet LED Light Sources

WHITE PAPER: Measuring UVA & Violet LED Light Sources As the development of new UV LED sources continues at an ever-growing pace, so do the industrial applications that utilize them. UV LEDs are being put to work in various industrial processes, medical applications, and disinfection solutions. Efficient utilization of the UV radiation requires good ... Read more »

FEATURED

Luminus Releases Hospitality COB Series for Hotels and Restaurants

Luminus Releases Hospitality COB Series for Hotels and Restaurants Luminus Devices has announced its new Hospitality COB series featuring high color rendering, precise chromaticity control and Warm CCTs. With LES sizes ranging from 6mm to 22mm, and lumen output from 500 to 5000 lumens, the Luminus Hospitality COB series is the smart choice for beautiful, warm ... Read more »

FEATURED

New Cree LED™ XLamp® XP-P LEDs Deliver Breakthrough Intensity

New Cree LED™ XLamp® XP-P LEDs Deliver Breakthrough Intensity Our name has changed, but our commitment to superior LED technology, reliability, innovation, support, and service remains steadfast. The same teams with years of Cree LED experience are newly energized to help our customers improve their LED-based products and develop new applications. Read more »

FEATURED

New LUXEON® SkyBlue™ LED Solution Simplifies and Speeds Development of Human-Centric Lighting

New LUXEON® SkyBlue™ LED Solution Simplifies and Speeds Development of  Human-Centric Lighting Lumileds today announced the immediate availability of its new LED human-centric lighting solution – LUXEON SkyBlue. In partnership with BIOS Lighting, Lumileds has engineered a circadian lighting solution that delivers superior melanopic ratios at comfortable CCTs – 3000K, 3500K, and 4000K – with ... Read more »

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