Category Archives: LEDs

Kateeva  announced that it has closed its Series D round with $38 million in financing. The newest participant is Samsung Venture Investment Corporation (SVIC). Existing investors also contributed. They include: Sigma Partners, Spark Capital, Madrone Capital Partners, DBL Investors, New Science Ventures, and VEECO Instruments, Inc.

The company has raised more than $110 million since it was founded in 2008.

Kateeva makes the YIELDjet™ platform — a precision deposition platform that leverages inkjet printing to mass produce flexible and large-size OLED panels. The new funds will be used to support the company’s manufacturing strategy and expand its global sales and support infrastructure. Production systems are currently being built at the company’s facility in Menlo Park, Calif. to fulfill early orders.

The funding news coincides with the 2014 OLEDs World Summit taking place this week in Berkeley, Calif.

“Kateeva is a technology leader and has built a significant business in the OLED space,” said Michael Pachos, Senior Investment Manager at SVIC. “The company has demonstrated both a technical and business vision in driving adoption of OLED displays and lighting, and we look forward to contributing to its progress.”

“We believe that OLEDs on flexible substrates play a major role in the insatiable quest for ultra-durable, high-performance, and unbreakable mobile displays, and Kateeva has proven to hold the keys to a critical industry problem,” said Fahri Diner, Managing Director of Sigma Partners and a member of the Board of Directors of Kateeva. “Moreover, we are very excited about Kateeva’s impressive innovations that are poised to make large-panel OLED televisions finally an affordable reality — perhaps the Holy Grail of the display world. In partnership with SVIC, we’re delighted to offer continued support to Kateeva as they rapidly scale operations to support accelerating demand for OLED manufacturing solutions,” Diner continued.

Kateeva Chief Executive Officer Alain Harrus said: “SVIC’s investment speaks volumes about our technology’s enabling value to world-class OLED producers. It will reinforce our leading position and help serve all our customers better. Also, we appreciate our existing investors for their enduring commitment and trusted guidance. Thanks to their confidence in our technology and execution, mass producing OLEDs will be much smoother for leading display manufacturers.”

Common thermal considerations in LEDs include test point temperature and thermal power.

One characteristic typically associated with While it’s true that LEDs are cool relative to filaments found in incandescent and halogen lamps, they do generate heat within the semiconductor structure, so the system must be designed in such a way that the heat is safely dissipated. The waste heat white LEDs generate in normal operation can damage both the LED and its phosphor coating (which converts the LED’s native blue color to white) unless it’s properly channeled away from the light source.

A luminaire’s thermal design is specified to support continuous operation without heat damage and oftentimes separates the LEDs from temperature-sensitive electronics, which provides an important advantage over individual LED replacement bulbs.

Test point temperature
Test point temperature (Tc) is one characteristic that plays an important role during integration to determine the amount of heat sinking, or cooling, that the luminaire design requires. In general, the higher the Tc limit compared to worst-case ambient temperature (Ta), the more flexibility a luminaire manufacturer will have in designing or selecting a cooling solution.

The worst-case ambient temperature is usually 40ºC or higher, so a module with a low Tc rating (e.g., 65ºC) doesn’t have much headroom above the already hot ambient temperature. Trying to keep a module at Tc 65ºC when the Ta is 40ºC and dissipating 40W thermal power is very difficult to do with a passive heat sink, so a fan or other active heat sink will likely be required. On the other hand, a module with a Tc rating of 90º C or higher (while still meeting lumen maintenance and warranty specifications) has at least 50º C headroom over the ambient temperature and should be able to make use of a reasonably sized passive heat sink.

However, the higher you can push the test point on the LED module, the smaller the heat sink you need. It’s dependent on the Ta – if the module can’t withstand a high enough maximum temperature, it’s impossible to cool below Ta unless you have a refrigerated system, regardless of the size or effectiveness of the heat sink. Stretching the difference between Tc and Ta as much as possible will give you greater room to deviate from the norm and be creative in your heat sink selection.

From phosphor to where the heat sink is located, Xicato is driving Corrected Cold Phosphor to lower the resistance between the phosphor and the heat sink, without having to cool through the hot LEDs. Today, the module output is at 4000 lumens, which wouldn’t have been possible five years ago.

The bottom-line considerations with respect to test point temperature are really flexibility and cost. If a module with a high Tc rating is chosen, there will be more options for design and cost savings than are provided by a module with a low Tc rating, assuming the same power dissipation.

Figure 1: Xicato XSM module family sample passive heat sink matrix showing suitable module usage for a range of thermal classes.

Thermal power
Another key characteristic, thermal power (load) has always been a difficult number to deal with. LED module manufacturers don’t always provide the information required to calculate thermal power because this value can change based on such variables as lumen package, Color Rendering Index (CRI), correlated color temperature (CCT), etc. Cooling solutions are often rated for performance in terms of degrees Celsius per watt, which, unfortunately, necessitates calculating the thermal power.

To address this problem, Xicato has developed a “class system,” through which each module variation is evaluated and assigned a “thermal class.” With this system, determining the appropriate cooling solution is as simple as referencing the thermal class from the module’s data sheet to a matrix of heat sinks. FIGURE 1 is a sample passive heat sink thermal class matrix for the Xicato XSM module family.

Let’s take, as an example, a 1300 lumen module with a thermal class rating of “F.” According to the matrix, for an ambient condition of 40°C, the best choice of heat sink would be one that is 70 mm in diameter and 40 mm tall. Validation testing is still required for each luminaire during the design phase, as variations in trims, optics, and mechanical structures can affect performance. Looking at the example module, if a manufacturer were to design a luminaire around this class “F” heat sink and nine months later a new, higher-flux class “F” module were released, the same luminaire would be able to support the higher-lumen module without the need for additional thermal testing. The thermal-class approach supports good design practice, speeds development and product portfolio expansion, and provides a future-proof approach to thermal design and integration.


Most specification sheets cite an electrical requirement for the module and the lumen output. Electrical input is basically the voltage the module will require and the current needed to drive it; the product of these two variables is power. The problem with output is that it’s always displayed in lumens – a lumen is not a measure of power, but rather a unit that quantifies and draws optical response to the eye. It’s calibrated specifically on what the human eye sees, but there’s a quality of brightness that comes into play that can’t easily be tied back to electrical power. There’s no way to figure out exactly how much thermal power is being dissipated by the module – power “in” is measured in electrical energy (voltage × current), while power “out” is non-visible electromagnetic, visible electromagnetic, and thermal power. None of this is shown in datasheets.

This intangible factor creates a challenge – for most customers, a watt is a watt, but in reality, there are thermal watts, electrical watts and optical watts; not all are easily determined. The customer can attempt calculations – e.g., how to cool 10 thermal watts – but the fact is that people don’t generally think that way. Many customers don’t have engineers on staff, and those that do often use rough approximations to determine compatibility.

Xicato has defined modules that go up to Class U. The Tc rating, while independent of module flux package, is interrelated. Class A modules, in general, don’t need a heat sink; lower power modules usually achieve about 300 lumens. On the other hand, an XLM 95 CRI product is a Class U product that requires either a passive heat sink or an active heat sink. Once the module and heat sink have been selected and integrated into the luminaire, the next step is thermal validation, which Xicato performs for the specific fixture utilizing an intensive testing process that includes detailed requirements that must be met by the luminaire maker when submitting a fixture for validation (see Table 1 for a partial summary).

The validation is based not on lumens, but on the thermal class model, and the fixture rating is also based on thermal class, rather than wattage, because watts differ. With this approach, an upgrade can be made easily without having to do any retesting. •

JOHN YRIBERRI, Xicato, is the director of Global Application Engineering, Xicato, Inc., San Jose, CA. John joined Xicato in November of 2007 and was the Project leader for Xicato’s first LED platform- the Xicato Spot Module (XSM).

In its Research Bulletin dated August 2, 2013, IC Insights published its list of the top semiconductor sales leaders for the first half of 2013. The list showed the usual big-time players that we’ve come to expect like Intel, Samsung, and TSMC, leading the way in semiconductor sales through the first six months of the year. What stood out nearly as much, however, was that only one Japanese company—Toshiba—was present among the top 10 suppliers through the first half of 2013.  Anyone who has been involved in the semiconductor industry for a reasonable amount of time realizes this is a major shift and a big departure for a country that once was feared and revered when it came to its semiconductor manufacturing presence on the global market.

Figure 1 traces the top 10 semiconductor companies dating back to 1985, when Japanese semiconductor manufacturers wielded their influence on the global stage.  That year, there were five Japanese companies ranked among the top 10 semiconductor suppliers.  Then, in 1990, six Japanese companies were counted among the top 10 semiconductor suppliers—a figure that has not been matched by any country or region since.  The number of Japanese companies ranked in the top 10 in semiconductor sales slipped to four in 1995, then fell to three companies in 2000 and 2006, two companies in 2012, and then to only one company in the first half of 2013.

Read more: First half of 2013 shows big changes to the top 20 semiconductor supplier ranking

It is worth noting that Renesas (#11), Sony (#16), and Fujitsu (#22) were ranked among the top 25 semiconductor suppliers in 1H13, but Sony has been struggling to re-invent itself and Fujitsu has spent the first half of 2013 divesting most of its semiconductor operations.

Japan’s total presence and influence in the semiconductor marketplace has waned.  Once-prominent Japanese names now gone from the top suppliers list include NEC, Hitachi, Mitsubishi, and Matsushita. Competitive pressures from South Korean IC suppliers—especially in the DRAM market—have certainly played a significant role in changing the look of the top 10.  Samsung and SK Hynix emulated and perfected the Japanese manufacturing model over the years and cut deeply into sales and profits of Japanese semiconductor manufacturers, resulting in spin-offs, mergers, and acquisitions becoming more prevalent among Japanese suppliers.

  • 1999 — Hitachi and NEC merged their DRAM businesses to create Elpida Memory.
  • 2000 — Mitsubishi divested its DRAM business into Elpida Memory.
  • 2003 — Hitachi merged its remaining Semiconductor & IC Division with Mitsubishi’s System LSI Division to create Renesas Technology.
  • 2003 — Matsushita began emphasizing Panasonic as its main global brand name in 2003.  Previously, hundreds of consolidated companies sold Matsushita products under the Panasonic, National, Quasar, Technics, and JVC brand names.
  • 2007 — To reduce losses, Sony cut semiconductor capital spending and announced its move to an asset-lite strategy—a major change in direction for its semiconductor business.
  • 2010 — NEC merged its remaining semiconductor operations with Renesas Technology to form Renesas Electronics.
  • 2011 — Sanyo Semiconductor was acquired by ON Semiconductor.
  • 2013 — Fujitsu and Panasonic agreed to consolidate the design and development functions of their system LSI businesses.
  • 2013 — Fujitsu sold its MCU and analog IC business to Spansion.
  • 2013 — Fujitsu sold its wireless semiconductor business to Intel.
  • 2013 — Elpida Memory was formally acquired by Micron.
  • 2013 — After failing to find a buyer, Renesas announced plans to close its 300mm and 125mm wafer-processing site in Tsuruoka, Japan, by the end of 2013.  The facility makes system-LSI chips for Nintendo video game consoles and other consumer electronics.
  • 2013 — Unless it finds a buyer, Fujitsu plans to close its 300mm wafer fab in Mie.

Besides consolidation, another reason for Japan’s reduced presence among leading global semiconductor suppliers is that the vertically integrated business model that served Japanese companies so well for so many years is not nearly as effective in Japan today.  Due to the closed nature of the vertically integrated business model, when Japanese electronic systems manufacturers lost marketshare to global competitors, they took Japanese semiconductor divisions down with them.  As a result, Japanese semiconductor suppliers missed out on some major design win opportunities for their chips in many of the best-selling consumer, computer, and communications systems that are now driving semiconductor sales.

It is probably too strong to suggest that in the land of the rising sun, the sun has set on semiconductor manufacturing.  However, the global semiconductor landscape has changed dramatically from 25 years ago. For Japanese semiconductor companies that once prided themselves on their manufacturing might and discipline to practically disappear from the list of top semiconductor suppliers is evidence that competitive pressures are fierce and that as a country, perhaps Japan has not been as quick to adopt new methods to carry on and meet changing market needs.

O2Micro(R) International Limited today introduced the patent pending OZ2083 3-Way LED Bulb Driver Controller with Power Factor Correction.

Read more LED news

Three-way desk, table and floor lamps are ubiquitous in the United States, providing consumers with the convenience of high, medium and low brightness in a single bulb. However, today’s 3-way lamps are based on energy inefficient incandescent bulbs. Furthermore, the filaments in 3-way incandescent bulbs burn out at different rates, creating reliability problems and a poor consumer experience.

LED-based, 3-way bulbs provide significant efficiency improvements versus their incandescent counterparts. In addition, they provide much longer operating life, eliminating the reliability problems that plague 3-way incandescent bulbs. But until now, there has been no easy and cost effective way to design the complex driver circuitry required for a 3-way LED bulb. O2Micro’s OZ2083 solves this problem.

The OZ2083 3-Way LED Bulb Driver Controller with Power Factor Correction is a Buck converter controller utilizing quasi-resonant technology. The device provides two detection inputs based on proprietary technology to support 3-way, 2-circuit sockets used within 3-way desk, table, and floor lamps to produce three levels of LED brightness in a low-medium-high configuration. Using the OZ2083, manufacturers can easily and rapidly develop drop-in LED bulb replacements for today’s 3-way incandescent bulbs.

The OZ2083 is a highly optimized controller for non-isolated Buck converter off-line applications. The device features the highest level of integration, reducing the system level driver bill of material (BOM) cost and component count to industry-leading levels. An external MOSFET provides the flexibility to support a range of application requirements.

The OZ2083 supports universal 85V to 265V operation, enabling one LED bulb to address the global marketplace. Integrated power factor correction enables high power factor and low Total Harmonic Distortion

(THD) over a wide input voltage range to meet both residential and commercial requirements, further helping OEMs meet global regulatory requirements.

High efficiency greater than 88% reduces energy consumption and thermal management complexity. Integrated over-temperature, over-voltage, cycle-by-cycle current limiting, LED open circuit and LED short circuit protection and maximum gate drive output clamp provide safe and reliable operation. Excellent LED current regulation ensures consistent lumen output, regardless of varying line input conditions.


M/A-COM Technology Solutions Holdings, Inc., a supplier of high performance RF, microwave, and millimeter wave products, today announced it has filed suit in the United States District Court for the Northern District of California against GigOptix, Inc. (NYSE MKT:GIG) for patent infringement.

The complaint alleges that GigOptix makes, uses, imports, offers to sell, and/or sells in the United States electro-optics polymers containing chromophores that infringe two MACOM patents, including certain GigOptix Mach-Zehnder modulator products that GigOptix markets or promotes as containing "Thin Film Polymer on Silicon (‘TFPS(TM)’)" technology. MACOM is seeking injunctive relief barring the infringement, as well as monetary damages, including treble damages based on allegedly willful infringement by GigOptix, attorney’s fees and costs of suit.

"MACOM has built a substantial patent portfolio through investment in innovation, and will defend that investment vigorously when required," said Ray Moroney, Optoelectronics Product Line Manager for MACOM. "We look forward to a just resolution of this matter through the legal process."

The market for semiconductors used in industrial electronics applications relished a better-than-expected first quarter as macroeconomic headwinds turned out to be less severe than initially feared, according to the latest Industrial Electronics report from information and analytics provider IHS.

Worldwide industrial electronics chip revenue in the first quarter reached $7.71 billion, up 1 percent from $7.63 billion in the final quarter of 2012. Although the uptick seemed modest, the increase marked a turnaround from the three percent decline in the fourth quarter. It also represents a major improvement compared to the 3 percent contraction of the market a year ago in the first quarter of 2011, as shown in the figure below.


“The industrial semiconductor market’s performance was encouraging, especially in light of continuing global economic uncertainty and the seasonal nature of the market, which typically sees slower movement in the first quarter of every year,” said Robbie Galoso, principal analyst for electronics at IHS. “Some large segments of the industry, particularly avionics and oil and gas process-automation equipment, saw muscular double-digit gains, helping to drive up overall revenue.”

In another positive development, several large industrial semiconductor suppliers also reported very lean inventories because of strong orders from customers. Infineon Technologies of Germany, Analog Devices of Massachusetts, and Dallas-based Texas Instruments all posted a sequential decline in industrial chip stockpiles as their days of inventory (DOI) measure fell well below average. Infineon achieved higher sales from increased volume in isolated-gate bipolar transistor (IGBT) chips; Analog Devices was strong in factory automation and medical instrumentation; and Texas Instruments saw growth in its analog products.

Other companies reporting sound increases during the period were Xilinx of California for its test and measurement, military aerospace and medical product lines; and Microsemi, also from California, which likewise enjoyed expansion in medical electronics along with broad-based growth for the period.

Europe’s woes inhibit industry, but China counters with growth

However, the industry was not without its challenges, with the Eurozone crisis causing the most havoc.

Read more: Regional developments to affect the growth of semiconductor industry

“The financial troubles on the continent, particularly in Greece, Italy and Spain, had the effect of stifling growth as a whole, especially in the commercial market for building and home control,” Galoso said. “As a result, the individual sectors for lighting, security, climate control and medical imaging were deleteriously impacted in the first quarter, compared to positive performance for those areas in the fourth quarter of 2012.

In contrast to Europe’s woes was China, which displayed growth momentum and much-improved demand across a number of industrial end markets. Manufacturers like Siemens of Germany, Philips of the Netherlands, Swiss-based ABB and Schneider Electric of France said their first-quarter sales in China improved from the earlier quarter.

In the rare earth industrial sector, however, China’s hold on the market loosened as rare earth prices started going south this year. China had a more than 90 percent monopoly on rare earth elements in the past, but new sources in Australia, the United States, Brazil, Canada and South Africa have opened up the market, decreasing dependence on China.

Products that incorporate rare earth materials include wind turbines, rechargeable batteries for electric vehicles and defense applications, including jet-fighter engines, missile guidance systems, and space satellites and communications systems.

Aerospace flies high; oil and gas equipment is also a winner

The military and civil aerospace market had the most robust performance among all industrial semiconductor segments in the first quarter. Avionics was especially vigorous, driven by commercial aircraft sales from pan-European entity EADS Airbus and U.S. maker Boeing, up 9 percent and 14 percent, respectively, on the quarter.

The oil and gas exploration market also saw solid revenue growth, with strong subsea systems and drilling equipment driving sales for ABB, Honeywell and GE.

In contrast to those high-performing segments, lackluster sales were reported in the markets for building and home control, for energy generation and distribution, and for test and measurement. One other market, manufacturing and process automation, reported stable growth, even though its sector for motor drives remained in negative territory.

For most of us, a modern lifestyle without polymers is unthinkable…if only we knew what they were. The ordinary hardware-store terms we use for them include "plastics, polyethylene, epoxy resins, paints, adhesives, rubber" — without ever recognizing the physical and chemical structures shared by this highly varied — and talented — family of engineering materials.

Polymers increasingly form key components of electronic devices, too — and with its ever-escalating pursuit of high efficiency and low cost, the electronics industry prizes understanding specific behaviors of polymers. The ability of polymers to conduct charge and transport energy is especially appealing.

Now there’s help in appreciating the polymer mystique related to the emerging field of molecular conduction in which films of charge-transporting large molecules and polymers are used within electronic devices. These include small-scale applications such as light emitting diodes (LED). At the other end of the scale, in cities and across oceans, the polymer polyethylene is the vital insulating component in the reliable and safe transport of electrical energy by high voltage underground cables.

In work appearing in the current edition of the Journal of Applied Physics, researchers at the United Kingdom’s Bangor University describes how electrical charges may leak away to the ground through its labyrinth of molecules.

Researchers Thomas J. Lewis and John P. Llewellyn pay particular attention to the nano-scale structure of polyethylene in which crystalline regions are separated by areas known as "amorphous zones." Their novel employment of superexchange and quantum mechanical tunneling of electrons through the amorphous parts of the polymer helps improve understanding of electrical charge conduction.

"These findings could lead not only to improved properties of high voltage cables but also to a wider understanding of polymer semiconductors in device applications," said Lewis.

Their investigation shows that the tunneling feature accounts for the majority of the reported high-field charge transport effects in polyethylene.

Researchers at the Georgia Institute of Technology want to put your signature up in lights – tiny lights, that is. Using thousands of nanometer-scale wires, the researchers have developed a sensor device that converts mechanical pressure – from a signature or a fingerprint – directly into light signals that can be captured and processed optically.

The sensor device could provide an artificial sense of touch, offering sensitivity comparable to that of the human skin. Beyond collecting signatures and fingerprints, the technique could also be used in biological imaging and micro-electromechanical (MEMS) systems. Ultimately, it could provide a new approach for human-machine interfaces.

Read more: Driven by Apple and Samsung, light sensors achieve double-digit growth

"You can write with your pen and the sensor will optically detect what you write at high resolution and with a very fast response rate," said Zhong Lin Wang, Regents’ professor and Hightower Chair in the School of Materials Science and Engineering at Georgia Tech. "This is a new principle for imaging force that uses parallel detection and avoids many of the complications of existing pressure sensors."

piezo LED

Individual zinc oxide (ZnO) nanowires that are part of the device operate as tiny light emitting diodes (LEDS) when placed under strain from the mechanical pressure, allowing the device to provide detailed information about the amount of pressure being applied. Known as piezo-phototronics, the technology – first described by Wang in 2009 – provides a new way to capture information about pressure applied at very high resolution: up to 6,300 dots per inch. The research was scheduled to be reported August 11 in the journal Nature Photonics. It was sponsored by the U.S. Department of Energy’s Office of Basic Energy Sciences, the National Science Foundation, and the Knowledge Innovation Program of the Chinese Academy of Sciences.

 Piezoelectric materials generate a charge polarization when they are placed under strain. The piezo-phototronic devices rely on that physical principle to tune and control the charge transport and recombination by the polarization charges present at the ends of individual nanowires. Grown atop a gallium nitride (GaN) film, the nanowires create pixeled light emitters whose output varies with the pressure, creating an electroluminescent signal that can be integrated with on-chip photonics for data transmission, processing and recording.

"When you have a zinc oxide nanowire under strain, you create a piezoelectric charge at both ends which forms a piezoelectric potential," Wang explained. "The presence of the potential distorts the band structure in the wire, causing electrons to remain in the p-n junction longer and enhancing the efficiency of the LED."

The efficiency increase in the LED is proportional to the strain created. Differences in the amount of strain applied translate to differences in light emitted from the root where the nanowires contact the gallium nitride film.

Read more: Student develops brighter, smarter and more efficient LEDs

To fabricate the devices, a low-temperature chemical growth technique is used to create a patterned array of zinc oxide nanowires on a gallium nitride thin film substrate with the c-axis pointing upward. The interfaces between the nanowires and the gallium nitride film form the bottom surfaces of the nanowires. After infiltrating the space between nanowires with a PMMA thermoplastic, oxygen plasma is used to etch away the PMMA enough to expose the tops of the zinc oxide nanowires.

piezo LED 2

A nickel-gold electrode is then used to form ohmic contact with the bottom gallium-nitride film, and a transparent indium-tin oxide (ITO) film is deposited on the top of the array to serve as a common electrode. When pressure is applied to the device through handwriting, nanowires are compressed along their axial directions, creating a negative piezo-potential, while uncompressed nanowires have no potential. The researchers have pressed letters into the top of the device, which produces a corresponding light output from the bottom of the device. This output – which can all be read at the same time – can be processed and transmitted. The ability to see all of the emitters simultaneously allows the device to provide a quick response. "The response time is fast, and you can read a million pixels in a microsecond," said Wang. "When the light emission is created, it can be detected immediately with the optical fiber."

The nanowires stop emitting light when the pressure is relieved. Switching from one mode to the other takes 90 milliseconds or less, Wang said.

The researchers studied the stability and reproducibility of the sensor array by examining the light emitting intensity of the individual pixels under strain for 25 repetitive on-off cycles. They found that the output fluctuation was approximately five percent, much smaller than the overall level of the signal. The robustness of more than 20,000 pixels was studied.

A spatial resolution of 2.7 microns was recorded from the device samples tested so far. Wang believes the resolution could be improved by reducing the diameter of the nanowires – allowing more nanowires to be grown – and by using a high-temperature fabrication process.

Computer simulations have revealed how the electrical conductivity of many materials increases with a strong electrical field in a universal way. This development could have significant implications for practical systems in electrochemistry, biochemistry, electrical engineering and beyond.

The study, published in Nature Materials, investigated the electrical conductivity of a solid electrolyte, a system of positive and negative atoms on a crystal lattice. The behavior of this system is an indicator of the universal behavior occurring within a broad range of materials from pure water to conducting glasses and biological molecules.

Electrical conductivity, a measure of how strongly a given material conducts the flow of electric current, is generally understood in terms of Ohm’s law, which states that the conductivity is independent of the magnitude of an applied electric field, i.e. the voltage per metre.

This law is widely obeyed in weak applied fields, which means that most material samples can be ascribed a definite electrical resistance, measured in Ohms.

However, at strong electric fields, many materials show a departure from Ohm’s law, whereby the conductivity increases rapidly with increasing field. The reason for this is that new current-carrying charges within the material are liberated by the electric field, thus increasing the conductivity.

Remarkably, for a large class of materials, the form of the conductivity increase is universal – it doesn’t depend on the material involved, but instead is the same for a wide range of dissimilar materials.

The universality was first comprehended in 1934 by the future Nobel Laureate Lars Onsager, who derived a theory for the conductivity increase in electrolytes like acetic acid, where it is called the "second Wien effect." Onsager’s theory has recently been applied to a wide variety of systems, including biochemical conductors, glasses, ion-exchange membranes, semiconductors, solar cell materials and to "magnetic monopoles" in spin ice.

Researchers at the London Centre for Nanotechnology (LCN), the Max Plank Institute for Complex Systems in Dresden, Germany and the University of Lyon, France, succeeded for the first time in using computer simulations to look at the second Wien effect. The study, by Vojtech Kaiser, Steve Bramwell, Peter Holdsworth and Roderich Moessner, reveals new details of the universal effect that will help interpret a wide varierty of experiments.

Professor Steve Bramwell of the LCN said: "Onsager’s Wien effect is of practical importance and contains beautiful physics: with computer simulations we can finally explore and expose its secrets at the atomic scale.

"As modern science and technology increasingly explores high electric fields, the new details of high field conduction revealed by these simulations, will have increasing importance."

Displaybank’s recent market report on the cost competiveness of LED chips. This report conducts a thorough analysis on the supply price history, trends and forecast of main materials that compose packaged LEDs across the entire LED value chain. The key materials include sapphire ingot, substrate, LED chip (or die), frame (PCB, lead frame, ceramic), phosphor (YAG, silicate, nitride), and encapsulation. The supply price of the key materials used in the production of a packaged LED was assumed as the production cost. In addition, IHS has researched the average selling price (ASP) of a packaged LED every quarter since 2010, aside from this report.

In 2012, the 4-inch ingot/substrate lost its price premium compared to the 2-inch product, and the 6-inch product had to lower its margin because of excess supply in 2013. However, such drastic fluctuations in price are not expected to occur after 2014.

The LED chip suppliers have reaped great benefits with the falling production cost of 4-inch-substrate-based LED chips. However, it is expected that they will convert their production systems over to 6-inch or 8-inch substrates in the near future, with the falling prices of 6-inch substrates and enhanced yield rates. According to the report, the production cost competitiveness of LED chips produced on 6-inch substrates will outstrip that of 4-inch, by as early as 2015.

In addition, the report compares the production cost and selling price of packaged LEDs by application; analyzes the margin and cost structure; and forecasts for the cost and price until 2020.