Osram Opto unveils R&D results from GaN LEDs grown on silicon

Prototype LEDs fabricated from GaN-based layers grown on 150-mm-diameter silicon substrates are similar in performance to standard production devices grown on sapphire.
Osram Opto Semiconductors has reported a set of R&D results from LEDs fabricated using gallium nitride (GaN)-based layers deposited on silicon. The R&D devices made using GaN-on-Si material have performance levels that are similar to production devices fabricated on sapphire.

GaN LEDs on 6-inch silicon

Most GaN-based LEDs are grown on sapphire or silicon carbide substrates. While Osram Opto has already started moving its standard production of GaN-based LEDs to 6-inch (150-mm) diameter sapphire substrates, the real prize in moving to production on silicon wafers is the availability of larger, lower-cost substrates.
The new LED chips are already in the pilot stage, and will be tested under practical conditions, says Osram, adding that its first LEDs fabricated on silicon could hit the market in just two years.


“Our investments in years of research are paying off, because we have succeeded in optimizing the quality of the gallium-nitride layers on the silicon substrates to the point where efficiency and brightness have reached competitive market levels,” said Peter Stauss, project manager at Osram Opto Semiconductors. “Stress tests we've already conducted demonstrate the high quality and durability of the LEDs, two of our traditional hallmarks.”


The GaN-on-Si chips were fabricated using Osram’s thin-film UX:3 process, which involves transfer to a silicon carrier and removal of the original silicon substrate (see diagram).
Blue UX:3 chips in the standard Golden Dragon Plus package achieved an optical power of 634 mW at 3.15V, equivalent to 58 percent efficiency. These are very good values for 1-mm2 chips at 350 mA.


Thin-film fabrication of GaN-on-Si
In combination with a conventional phosphor converter in a standard housing, prototype white LEDs produced 140 lm at 350 mA with an efficiency of 127 lm/W at 4500K.
“For these LEDs to become widely established in lighting, the components must get significantly cheaper while maintaining the same level of quality and performance,” said Stauss. “We are developing new methods along the entire technology chain for this purpose, from chip technology to production processes and housing technology.”
Mathematically speaking, it is already possible today to fabricate over 17,000 LED chips measuring 1-mm2 on a 150-mm wafer. Larger silicon wafers could increase productivity even more; researchers have already demonstrated the first structures on 200-mm (approx. 8-inch) substrates.


Development details
LEDs Magazine spoke with Strauss and Ulrich Steegmueller, Osram Opto’s chief technology officer, who will discuss this and other subjects in his presentation at Strategies in Light 2012. “About three years ago we began a research project looking at the MOCVD growth of GaN on silicon,” said Steegmueller. At that stage it was very unclear whether the technology could approach similar levels to GaN-on-sapphire growth.”


Initially, Osram Opto worked with Azzurro Semiconductors, another German company, using technology developed at, and transferred from, the University of Madgeburg. Recent work carried out internally by Osram Opto has been funded in part by the German Federal Ministry of Education and Research as part of its “GaNonSi” project network.


“We started initially on 2-inch silicon, and quickly moved to 4-inch,” said Strauss. “Of course, we have moved to 150-mm manufacturing on sapphire in production, and our latest GaN-on-Si results are on 150-mm wafers. The eventual goal will be to move to 200-mm silicon or larger, which would be very difficult using sapphire.”


The biggest challenge is successful MOCVD growth of the GaN-based layers. This requires complex stress engineering within the structure to overcome the difference in the thermal expansion coefficients of the different materials. Homogeniety and uniformity of the MOCVD-grown structure is very important, in order to make full use of the larger wafers and ultimately to achieve high yield in production. Steegmueller said that the uniformity is similar to material grown on sapphire.

Since silicon absorbs the emitted light, the substrate must be removed after growth. Thin-film LED structures are widely used by Osram Opto, and while the actual technology for removing the substrate is different for sapphire and silicon, the overall processes are compatible. Steegmueller points out that, because a thin-film approach (as opposed to wafer bonding to a carrier) is preferable, this creates a barrier to entry to companies that are not already working with thin-film structures.

Cree targets luminaire system cost with new XLamp XB-D LED

With the small-footprint XB-D LED, Cree intends to lower the cost, in terms of lumens per dollar, for SSL lamp and luminaire designs.
Cree has announced the new XLamp XB-D LED family that features components measuring 2.45x2.45 mm, that the company says will deliver double the lumens per dollar achievable at the system level. The small footprint will be especially suited to solid-state lighting (SSL) retrofit lamps, although Cree has said that the LEDs built with a new die structure will serve across a broad application base.
At 350-mA drive current and 85°C operating temperature, the new LED platform delivers 139 lm in 6000K-CCT, cool-white models, and 107 lm in 3000K-CCT, warm-white models. The efficacy is 136 and 105 lm/W respectively.

Warm-white XB-D

The LEDs feature a maximum drive current of 1A. The cool-white components can be specified with no minimum CRI value or optionally with a 70 CRI minimum. Neutral-white products feature a typical CRI value of 75 and can be specified at 80 CRI minimum. The warm-white LEDS feature a typical CRI of 80 and can also be specified at a minimum value of 80.



Hot binning across CCT range
There are several other notable features of the new family according to product marketing manager Paul Scheidt. He said that the XB-D is the first LED family to be hot-binned across all CCTs. Scheidt said, "Competitors only hot bin in the warm-white CCTs."
The new platform includes several elements that Cree says will help reduce system cost. Obviously the smaller die has a direct impact on component cost because Cree can manufacture more components per wafer. Cree did not directly address component cost. But the company did show a table that indicates the XB-D delivers more lumens and better efficacy than competing components that measure 3.5x3.5 mm and larger.
In part the performance comes from a new die architecture and packaging scheme, along with what Cree says are inherent advantages in its manufacturing process, a claim we will discuss a bit later. A photo of an XB-D LED with no phosphor applied revealed a beveled structure around the die designed to maximize light extraction.



Flexible lamp design
The smaller component footprint also provides designers of retrofit lamps far more flexibility in lamp design and the ability to include more LEDs in smaller spaces. For example, Scheidt showed an example of a standard A Lamp where the LEDs can be placed deeper in the neck of the lamp rather than at the equator of the globe, thereby providing better light distribution.

Cool-white XB-D

Scheidt also said that the small size simplifies the design of other elements such as secondary optics and reflectors. The same holds true for circuit boards. All of those simpler elements add to the potential for a lower system cost.
Cree believes the XB-D can increase the penetration of LED lamps in price-sensitive markets such as the residential space. Scheidt cited a Home Depot study in which the same lamps were sold for $20 in some select stores and for $10 in other select stores. According to Scheidt, the stores with the lower-priced lamps realized 6 to 10 times the sales volume.
About SSL lamps, Scheidt said, "The product itself is there in terms of technology. People accept it." He was speaking of aspects such as color and light quality while noting that cost remains the obstacle. But addressing current price levels, he added, "We're at least in the right order of magnitude." And presumably XB-D will help relieve another significant reduction.


Silicon-carbide manufacturing
Cree also took the occasion of the XB-D launch to emphasize what it belies is a competitive advantage of its gallium-nitride (GaN) on silicon-carbide (SiC) manufacturing process. Cree's Scheidt said that the SiC substrate offers numerous advantages over the sapphire substrates widely used by competitors.
Like many manufacturers of lighting-class LEDs, Cree uses a flip-chip approach in which the substrate side of the die is on the top side of the packaged LED. Scheidt said SiC offers a refractive index that better matches the GaN layers than does sapphire, thereby improving light extraction.

Scheidt further said that SiC offers a better match in terms of coefficient of thermal expansion resulting in fewer cracks. And that SiC results in smaller lattice-structure mismatches between the GaN and SiC layers thereby yielding more efficient LEDs.

CSA adds new LED lighting and EEV testing lab in Guangzhou

CSA International has expanded its laboratory capabilities in Guangzhou, China by adding energy-efficiency verification testing equipment to its existing LED lighting testing and certification services.


CSA International, a product testing and certification organization, has expanded its Guangzhou, China lab’s capabilities with the addition of new energy-efficiency verification (EEV) testing equipment to its existing LED lighting testing and certification services.
"The expansion to the Guangzhou lab further demonstrates CSA's continued commitment to expanding operations in Asia to provide its clients highly sophisticated and innovative localized testing and certification services for global markets," said Ash Sahi, president and CEO of the CSA Group.


In 2008, CSA established a joint venture, CCIC-CSA International Certification Company Limited, with the China Certification and Inspection Group (CCIC). In November 2008, CSA International opened its first China testing and certification laboratory in Guangzhou to meet demand from local producers of LED lighting products.


Located in the Guangzhou High-tech Development Zone, the new state-of-the-art lab comprises an area of over 3800 m2. The expanded facility is the second CSA Guangzhou laboratory. CSA’s team of highly-skilled engineers, testing specialists and technicians are well-trained professionals with extensive knowledge of North American and international standards.
Early last month, the organization opened a new testing and certification laboratory in Atlanta, GA. This 30,000 ft2 facility (2787 m2), is capable of testing LEDs and lighting products to 75 standards including Energy Star requirements.

Philips Lumileds appoints Pierre Yves Lesaicherre as new CEO

Pierre Yves Lesaicherre succeeds Michael Holt as CEO at LED maker Philips Lumileds and reports to Philips Lighting CEO Frans van Houten.


LED manufacturer Philips Lumileds kicked the new year off by announcing that Pierre Yves Lesaicherre has taken the position of CEO. Lesaicherre will report directly to acting Philips Lighting CEO Frans van Houten and takes the reigns in place of the retiring Michael Holt, who has led Lumileds since inception.


Under Holt, Philips Lumileds was a pioneer in the solid-state lighting (SSL) technology segment, and Philips Lighting clearly expects Lesaicherre to further that effort.
Van Houten said, "I'm confident Pierre Yves will drive Philips Lumileds' performance and actively shape the fast-changing LED illumination market."


Lesaicherre comes to the position after more than 20 years of experience in the semiconductor industry and from a position at NXP Semiconductors, a leading semiconductor manufacturer.
"Pierre Yves' tremendous experience at NXP Semiconductors, most recently as senior vice president and general manager of microcontrollers and logic, make him uniquely qualified to lead Philips Lumileds into the new world of lighting," said van Houten.


Van Houten also acknowledged the contribution that Holt made to Philips and the LED lighting industry. He said, "At the same time I also thank Mike Holt, Lumileds’ first CEO, who for more than a decade has led the company as it invented and introduced high-power LEDs and opened entirely new lighting segments. Mike is retiring to enjoy more time with his family."
Philips Lumileds was originally called Lumileds Lighting and was formed in 1999 as a joint venture of Philips Lighting and Agilent Technologies - a Hewlett-Packard spin off with some LED manufacturing technology. Philips acquired a controlling interest in 2005.

No LED replacement found for ornamental post-top street lights in DOE pilot project

An evaluation has determined that none of four different LED replacement products for ornamental post-top street lights could match the performance of the existing 100W HPS fixture.
The US Department of Energy (DOE) has published the final report from a demonstration of LED technology in ornamental post-top street lights, which was conducted in Sacramento, CA. Four different LED replacement products were evaluated using computer simulations, field measurements and laboratory testing. The evaluation was conducted by DOE's Municipal Solid-State Street Lighting Consortium in collaboration with the Sacramento Municipal Utility District and the City of Sacramento, with additional support from City consultant Mary Matteson Bryan.


In this pilot project, the study was restricted to lamp-ballast retrofit kits and complete luminaire replacements that would preserve the daytime appearance of the existing acorn-style luminaires. This challenge proved formidable, as the results indicate that none of the LED products evaluated could match the performance of the existing 100W high-pressure sodium (HPS) luminaires. The report, available for download, highlights some of the nuances involved in LED product selection.


To allow for apples-to-apples economic comparison, the pricing and input power of the LED products had to be scaled proportionately to represent hypothetical products which could match light levels from the HPS fixtures. Energy used by three of the scaled-up LED systems ranged from 63-90% of the baseline HPS. The fourth product would actually require an increase in energy use by 15%. None of the products would represent cost-effective alternatives to HPS.


In response to recent industry developments, the study also investigated the relative significance of mesopic multipliers offered in the new IES Lighting Handbook and the lumen maintenance extrapolation methodology offered in the new IES TM-21.
This pilot project is the first in a series conducted by the DOE Municipal Solid-State Street Lighting Consortium, which serves as an objective resource for LED product evaluation and a repository for valuable field experience and data. The data generated from this project may be useful to standards groups, manufacturers, and those considering retrofits to LED.

Tech Lighting announces remote-phosphor LED luminaire using Intematix optic

The Unilume LED Undercabinet System from Tech Lighting includes linear SSL fixtures that rely on the Chromalit remote-phosphor optics from Intematix.
Tech Lighting will unveil the Unilume LED Undercabinet Lighting System at the Dallas International Lighting Market in showroom #4705-TM, demonstrating the products January 19-23, 2012. The product family includes 13- and 19-inch linear solid-state lighting (SSL) fixtures that combine blue LEDs and an Intematix Chromalit remote-phosphor optic to generate uniform light.


Tech Lighting said that LEDs have been widely used in under-cabinet applications, but generally with discrete LED point sources that appear as dots on reflective surfaces such as countertops. The company says that the Unilume products deliver "an even, glare-free wash of light" along the entire length of the fixture.


"Unilume has several other benefits over traditional LED under-cabinet solutions," said Tech Lighting general manager Josh Weiss. "Because it eliminates the need for a diffusing lens, it’s extremely energy efficient, and we’re able to achieve 50-to-60 lm/watt depending on the length. Further, the entire lens is illuminated and sits at the surface of the housing creating a much wider beam distribution. This makes it possible to use fewer under-cabinet units spread at greater distances. Finally, because the phosphor sits away from the LED, it remains cooler, which ensures greater color consistency over time."


"Tech Lighting sought a way to employ LED technology in under-cabinet lighting while improving uniformity," said Julian Carey, senior director of marketing at Intematix. "We are pleased that Chromalit helped enable their striking design with both efficacy and light quality."
Luminaire design

The Unilume design utilizes 30 LEDs per foot. The company is using blue LEDs from T-Opto, a Toyota Tsusho business, along with the rectangular Chromalit optics.
The fixture includes a mixing chamber that Tech Lighting says is 98% reflective. The company said the combination of the mixing chamber and optic yields a fixture that is thinner and narrower than competing fixtures. The luminaire is less than 0.75-inches deep.


Lighting designers can combine the linear fixtures to create longer linear light sources. The fixtures include jumper connectors that link one unit to the next. Tech Lighting offers the products in 2700K- or 3000K-CCT options and with a choice of 80 or 90 CRI. The fixtures integrate a driver than also works with legacy triac dimmers.


Remote phosphor patents
The Tech Lighting announcement is also interesting in that it comes shortly after Cree proactively stated that companies making remote-phosphor luminaires or lamps will require a license to Cree's patents. Cree announced five luminaire makers with which it had consummated license agreements, and Tech Lighting is not among those five.


When asked about the potential of an intellectual property (IP) issues, a Tech Lighting spokesperson said that the company had addressed IP issues with Intematix and that they don't believe that they are violating anyone's IP.


Intematix declined to comment on the IP issues that its customers face but said that its Chromalit optics don't infringe on others' patents. Cree, however, clearly believes that the fixture makers should have license to its basic patents covering the generation of white light using a blue LED and phosphor (remote or local).

EV Group and Eulitha collaborate on nanopatterning tool for LED manufacturing

EV Group has announced a joint development agreement with Eulitha AG, whereby the companies will combine their expertise in nanolithography to develop a full-field exposure tool for patterning sapphire substrates.
EV Group (EVG), a supplier of lithography and wafer bonding equipment based in St. Florian, Austria, has announced that it has signed a joint-development and licensing agreement with Eulitha AG, a producer of nanopatterned wafers using EUV interference techniques.

EVG will integrate Eulitha's Phable mask-based ultraviolet (UV) photolithography technology with EVG's automated mask aligner product platform with the goal of developing a low-cost-of-ownership nanopatterning process to be used to manufacture high-brightness LEDs (HB-LEDs). First products are expected to ship later this year.
According to LED market research firm Strategies Unlimited (Mountain View, Calif.), the market for HB-LEDs is expected to grow from $11.2 billion in 2010 to $16.2 billion in 2014, driven by applications such as TV backlighting, mobile devices and general lighting. To meet this increased demand, LED manufacturers need to improve lighting efficiency while reducing manufacturing cost.
The system will combine Eulitha's full-field exposure technology with EVG's established mask alignment platform (EVG620) to provide automated fabrication of photonic nanostructures over large areas, and support the production of energy efficient LEDs, solar cells and liquid crystal displays. It combines the low-cost, ease-of-use and non-contact capabilities of proximity lithography with sub-micron resolution — making it ideally suited for use in patterning sapphire substrates in order to enhance the light extraction of LED devices.
"We believe the synergies of our respective technologies have great potential to provide the resolution and volume-production capabilities of lithography steppers at a fraction of the cost — enabling LED, optics and photonics manufacturers with extremely tight cost constraints the opportunity to extend their technology roadmaps to higher levels of performance," stated Harun Solak, CEO of Eulitha.

Lite-On projects increased LED sales in 2012

Lite-On has estimated a dramatic increase in sales this year due to a new contract and partnership agreements.
Lite-On Technology Corp., a manufacturer of LED lighting products based in Taiwan, has signed a partnership agreement with six lighting manufacturers and expects increased revenues for 2012 over 2011.


Due largely to the new contract, the company’s CEO, K.C. Terng, has estimated that its LED lighting product sales have experienced double-digit growth from the 20-million-module-per-month level in 2011.
Terng has reported that the worst days for the LED industry have gone and the industry will perform better in the new year, whether in the LED lighting sector or the back light sector.

Marvell announces smart LED lighting platform at CES

Marvell's lighting-control platform matches LED driver and ZigBee wireless ICs for network control of various light sources, and the CES demonstration will include a wireless gateway and control software running on a wireless tablet PC.
The potential for smart, adaptive, solid-state lighting (SSL) systems entice IC companies such as Marvell, and the company plans an extensive demonstration of such a system at the Consumer Electronics Show (CES) that begins Jan 10th in Las Vegas, NV. Marvell is announcing a new smart-lighting platform that combines an LED-driver IC and a ZigBee wireless IC, and works within the planned wireless demonstration.

Marvell's smart SSL platform includes ZigBee-enabled sensors and LED sources.

Marvell's smart SSL platform
Networks and adaptive controls promise to bolster lighting-centric energy savings. LEDs alone have the potential to save 80-85% of the energy used for lighting according to Lance Zheng, Marvell senior manager of technical marketing. Zheng said, "If you add controls with networking, you can further increase the savings by 40%."


Smart lighting platform
The nearby figure illustrates Marvell's planned CES demo. The company will combine a reference design of a wireless gateway that links to various LED light sources and sensors via the ZigBee wireless mesh network. The gateway will also use Wi-Fi to link with data networks and, in the case of the demo, a tablet PC running custom software to control the lights.
The second figure shows a circuit board that implements the reference-design gateway. The board includes the 88MC200 microcontroller (MCU) that includes Wi-Fi-centric capabilities and the 88W8782 Wi-FI support IC.


Marvell's wireless gateway design
Marvell also announced the new 88MZ100 ZigBee-enabled MCU that lighting manufacturers can combine with the company's 88EM8080/91 and 88EM8801 driver ICs to create a network-enabled luminaire or lamp.
The company also has developed a Linux-based software package that implements the gateway capabilities, and that is available to IC customers. Moreover, Marvell offers the application code to implement control schemes on a tablet or other type of PC.

Smart scenarios
While Marvell's Zheng focused on energy reduction, he noted many other potential uses for adding controls to lighting systems. Zheng suggested that in the future you might have ambient-lighting systems that deliver a lighting track as a complement to a movie similar to a sound track for audio effects. Tunable color is also a potential usage model with warmer temperatures early in the day and cooler temperatures at night.
Short term, however, the challenge is the cost of SSL systems. Zheng said, "The main reason that LEDs have not been deployed in the mass market is cost." With the cost of LED components dropping, the driver circuits become a more significant cost factor. Zheng sees more highly-integrated ICs as the enabler of lower cost lamps and luminaires.

Marvell's wireless gateway design.

Energy Focus LEDs light US Navy ship top to bottom

With over 600 LED lighting fixtures, the USS Chafee has become the first US Navy ship to be fitted with all-LED lighting.
Energy Focus, Inc. (OTC BB: EFOI.OB), a provider of energy-efficient LED lighting fixtures based in Solon, OH, has provided more than 600 new LED lighting fixtures for installation on USS Chafee (DDG 90).


The Naval Sea Systems Command (NAVSEA) provided additional details including the new fixtures' 50,000-hr lifespan compared to the 1,000-hr for the incandescent globes and 7,500-hr for the fluorescents they replaced.


The ship is expected to save more than $50,000 per year using the new lights. Savings are expected to exceed $100,000 per ship per year when the scope is expanded to include T12 fluorescent fixtures.


NAVSEA also reported that, in early 2012, the USS Preble (DDG 88) is expected to receive the same fixtures as well as LED lamp replacements for the ship’s two-foot fluorescent fixtures, which are the most common lighting on DDG 51-class ships.
“The 600 LED fixtures Energy Focus provided include fixtures using our IntelliTube single LED waveguide technology to replace fluorescent berth lights as well as a range of advanced LED globe lights to replace existing incandescent globe light fixtures,” said Roger Buelow, Energy Focus CTO.


“Energy Focus has also received an order to provide its newly developed IntelliTube replacement LED tubes to retrofit both the USS Chafee’s and USS Preble T12 fluorescent fixtures, the second Navy ship to receive all-new LED lighting. The cost savings are expected to be even greater since the fixture doesn’t need to be replaced.”


In a separate announcement, Energy Focus stated it has completed a revolving secured line of credit of up to $4.5 million with Rosenthal & Rosenthal, Inc. This new agreement is a three year secured revolving line of credit to which Energy Focus may borrow up to $4.5 million, subject to periodic adjustments based on company assets.

Samsung LED becomes part of Samsung Electronics

Samsung Electronics has announced that it will merge its LED division with its broader corporate entity effective April 1.
The Board of Directors of Samsung Electronics has announced its decision to seek a merger with Samsung LED Ltd, the Korea-based company's LED manufacturing subsidiary. The merger is expected to open global sales channels to the LED business and perhaps widen the company’s access to the lighting market.


The purpose of the merger is, says Samsung, "to nurture the LED business as Samsung Electronics’ future growth engine" by utilizing its advanced technology, manufacturing competency, and global sales network.
The merger deal is expected to be signed on January 20, 2012 and then go into effect from April 1, 2012 after receiving approval at Samsung Electronics’ and Samsung LED’s Board of Directors meetings.


Strategies Unlimited told LEDs Magazine that Samsung’s LED sales for Q1-Q3 2011 were down 15% year-over-year. Preliminary numbers for Q4 indicate weak sales relative to 2010 due to low capacity utilization (around 50%).