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Editorial: "Dr. Bob" Tells Us How White LEDs are Made
... We promised a new feature called "Ask Dr. Bob" and we're delivering. Our first official "Ask Dr. Bob" question came from someone who didn't quite understand how white LEDs are made, given there's supposedly no such thing as an inherent "white" LED. So we asked our three Dr. Bobs...
Jump down to the full story
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Features:
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Toyoda Gosei Announces New 1000mcd White LEDs
October 20, 2004...Toyoda Gosei Co., Ltd of Aichi, Japan, has formally announced, dated October
5th, their development and marketing of a 1000 mcd white LED, said by the company
to be "one of the brightest cellular phone backlight ever developed."
The new product evidently combines an improved TG blue LED with yellow phosphors
to achieve the higher luminosity. Toyoda Gosei arrives at their 1000 mcd value
by saying it is "obtained at a drive current 20 mA, with a smaller package
size compared to the conventional standard." The company intends to begin
shipping samples this month and intends to start mass production within "this
year" (presumably 2004, which has only two months left). Content continues for LIGHTimes SecondPage members... Opto Tech Forecasts 2005 Nichia Branded Output
Jo Ann McDonald, EditorOctober 20, 2004...In direct followup to our Oct.
14 coverage, Opto Tech Corporation of Taiwan has forecast that they will
ship a total of 500 milliion Nichia-branded blue-LED units in 2005. The source
is Opto Tech's President, Ming-der Lin as reported Monday in DigiTimes. 50
million units will be shipped in the first quarter, 100 million in Q-2 then
150 million in Q-3 and 200 million in Q-4. Lin added that Opto Tech is already
shipping small volumes and said that "several packaging firms in Taiwan,
China and South Korea are already at the design-in stages." He also noted
that Opto Tech is able to supply 50 million blue-LED units per month, while
Highlink Technology, Opto Tech's "strategic partner," is able to supply
10 million per month. Opto Tech has not yet announced the finalization of the
acquisition of Highlink, which remains imminent. Content continues for LIGHTimes SecondPage members... Cree Adds to XLamp FamilyOctober 20, 2004...Cree, Inc.'s newly announced
4550 series XLamp LED products are not only already available in production
quantities, but they've already been designed into advanced versions of two
Color Kinetics established products. The XLamp product family is considered
Cree's innovative, high power SSL technology that competes well with the incandescent
bulb and other conventional light sources, especially in architectural and accent
lighting and other general illumination applications. The new 4550 uses a medium
high-power surface mount package which is designed to operate at 1/2 Watt with
a typical operating current of 125mA and a footprint of 4.5 mm x 5.0 mm. The
4550 series is available in blue and green versions based on Cree's XB500 chips
as a light engine. The 4550 product is also available in a red version. Content continues for LIGHTimes SecondPage members... Sirenza Makes Management Changes
CompoundSemi News StaffOctober 19, 2004...RF component maker Sirenza Microdevices of Bloomfield, Colorado USA has announced
various shifts in senior management. As announced by Sirenza Robert Van Buskirk,
President and CEO, Gerald Quinnell was promoted to the position of chief strategy
officer (CSO) from executive VP, business development. In this newly created
position, Quinnell will oversee sales, advanced research and development, business
development and strategic marketing. Sirenza also moved Norm Hilgendorf to VP
business development and strategic marketing from his previous slot as VP sales
and marketing. R.E. "Skip" Hoover, previously executive director,
aerospace & defense business unit, will be promoted to the position of VP
sales. Joe Johnson will continue in his role as chief technology officer (CTO)
and lead Sirenza's initiatives in advanced research and IP development and to
enhance the linkage between product R&D and advanced R&D. These three
positions will report to Gerald Quinnell.
Further, Guy Krevet, vice president, operations, will move to the position
of vice president, aerospace & defense business unit, reporting to Charles
Bland, chief operating officer (COO). "Aerospace & defense continues
to be one of our most attractive segments for growth. We were fortunate to have
someone with Guy's experience to assume the leadership of this unit and continue
the growth that Skip has been instrumental in creating," said Charles
Bland. In additional news from Sirenza, the company announced
its new P package stripline couplers in the industry standard 6.35mm
x 5.08mm footprint. The first two couplers released in the family are the AM03P
(1700 -- 2000 MHz) and the AP03P (2000 -- 2300 MHz).
RFMD Starts Volume Shipment of Polaris and PAs to MotorolaOctober 19, 2004...RF Micro Devices of Greensboro, North Carolina USA has announced
volume production shipments of their Polaris Total Radio GSM/GPRS transceivers
and PowerStar power amplifier (PA) modules for use in the Motorola MPx220
handset, which Mot announced Oct. 15th. Alastair Upton, General Manager of the
digital cellular product line at RF Micro Devices, said, "We are extremely
pleased to announce our participation in this exciting new handset. This is
the first of several GPRS and GPRS/EDGE devices that will be available in the
market this month using POLARIS radios. This is a significant achievement in
the history of RF Micro Devices, and we look forward to quickly supporting additional
GPRS as well as next-generation EDGE handsets with our POLARIS transceivers
and industry-leading PAs." BOC Edwards Announces New System and China Ties
CompoundSemi News StaffOctober 19, 2004...BOC Edwards of Wilmington, Massachusetts USA has announced
a new addition to its range of vacuum coating systems for thin film deposition
processes. Called the TF600, the new system combines a 600 mm-wide coating chamber
with a high throughput, vacuum pumping system. The company also announced
its equity position in AUECC (Asia Union
Electronic Chemical Corporation). Formed in 2000, AUECC is a JV between The
BOC Group (through its BOC Edwards Line of Business) and UPC Technology,
which is part of the Mitac-Synnex Group. AUECC specializes in ultrapure chemicals
for the microelectronics industry and is strategically located near the Hsinchu
and Tainan science-based parks to support the area’s high-technology industries.
AUECC facilities are also located in Beijing, Tienjin and Shanghai, China. In
addition, BOC Edwards announced that AUECC is moving forward with plans to supply
wet process chemicals to the growing electronics manufacturing industry in China,
and has formed an equity joint venture with Shanghai Huayi (Group) Company.
The new venture is called Shanghai Huayi Microelectronic Material Co. Ltd.
Through the new UPC Technology-BOC Edwards joint venture, AUECC will use Shanghai
as a base to produce, package and distribute a full range of ultra high-purity
process chemicals for semiconductor and flat panel display industries. A new
plant, backed by an initial investment that is expected to exceed 170 million
RMB (US$20 million) is in the final design phase, with production slated for
mid-2005. According to Neels Kriek, managing director of materials and services
for BOC Edwards, "With the completion of this facility, and backed by
the experience and reputation of the parent companies, manufacturers can reduce
their dependence on imports and rely on local supply. The ultimate goal, of
course, is to give our customers in this region a wide range of wet chemical
solutions, in both product and service support, allowing them to concentrate
on their core business initiatives." AUECC Chairman, Perry Chuang added,
"It is estimated that by next year over 45,000 tons of high-purity wet
chemicals will be needed by process industries in the Shanghai area alone. The
new venture means we can deliver reliable, high-quality products in the near
term, as well as the resources to underpin local industries' long-term
growth".
Mantis Awarded £90,000 for Advanced Nanocluster Deposition Tool DevelopmentOctober 19, 2004...Mantis Deposition of Oxfordshire, UK a manufacturer of UHV deposition equipment,
has received a one year grant from the UK's Department of Trade and Industry
(DTI) in the amount of £90,000 to further develop an advanced nanocluster
deposition tool. The UK is funding the majority of the project which is also
supported by Sharp Laboratories of Europe, the University of Oxford and the
Instituto de Microelectronica de Madrid in Spain. Of 113 companies who applied,
only Mantis Deposition was granted approval for a research project. Small Business
and Enterprise Minister Nigel Griffiths says; "I am delighted that the
DTI has been able to support Mantis Deposition's innovative work in the field
of nanocluster deposition. Our Grant for Research and Development has helped
many thousands of small businesses innovate and develop."
The project goals are to design and build a “floating” nanocluster
deposition source which will be able to produce accelerated nanoclusters, as
well as investigating electrostatic optics to allow the beam to be steered and
focussed. This will enable the source to be used in systems where it is difficult
to bias the substrate. The optics will allow more complex experiments to be
undertaken by enabling patterning of the nanoclusters. Mantis already offers
commercially available nanocluster deposition sources and systems based upon
it’s “NanoGen” technology. However, in the NanoGen (without the
“floating” principle), the substrate must be directly biased for accelerated
impact of the nanoparticles. Some applications affected by this new research
program are optoelectronics, bio-sensors and surface physics. Company
news release
Terahertz Imaging Contract Targets Hidden ExplosivesOctober 19, 2004...Spire Corporation of Bedford, Massachusetts USA has been awarded a DoD Phase
II SBIR contract to apply Spire's AlGaAs quantum cascade laser terahertz radiation
technology to help develop a radiation imaging systems that could allow detection
of hidden explosives such as improvised explosive devices. The contract is for
$750,000 and was granted by the USA's high risk project development agency,
DARPA. According to Spire, terahertz radiation is suitable for this application
because radiation at the targeted wavelengths penetrates most container materials.
Terahertz radiation has wavelengths that are slightly longer than visible and
infrared, but shorter than microwaves. Because their energy is almost a million
times lower than that of x-rays, this non-ionizing radiation is not expected
to cause any harmful effects to humans or animals.
Roger Little, President and CEO of Spire Corporation, said, "We are
pleased to be developing terahertz imaging technology to advance the Nation's
defense against terrorism. There is a lot of interest in terahertz radiation
for this as well as other applications, including medical instruments. We intend
to pursue commercialization opportunities aggressively." Design of
the lasers will be carried out in collaboration with Professor Shun-Lien Chuang
of the University of Illinois at Urbana-Champaign, Department of Electrical
and Computer Engineering. Epitaxial growth of the proprietary cascade laser
structures as well as device fabrication will be carried out at Spire's Bandwidth
Semiconductor foundry. Company
news release
Nippon Sanso Completes Merger with Taiyo Toyo SansoOctober 19, 2004...Mainstay gas and related systems provider to the compound semi industry, Matheson
Tri-Gas of Parsippany, New Jersey USA used the occasion of a recent launch of
its new distributor development program, called ENABLE, to update 65
distributors on the status of their parent company and new structure. Official
October 1, 2004 Matheson's parent company, Nippon Sanso Corporation, merged
with Taiyo Toyo Sanso, forming Taiyo Nippon Sanso Corporation. Nippon Sanso
in Japan also provides the CS industry with MOCVD reactor platforms. Included
in the update to Matheson Tri-Gas distributors was the fact that Matheson also
acquired six divested MG Atmospheric Gas Facilities and Businesses as a result
of the Air Liquide acquisition of MG Industries was also discussed. More details
about the new distributor program are included in the company
news release. Our news features are reported
by the CompoundSemi News staff writers.
For submissions or content suggestions, you can contact us using
editor -at - compoundsemi.com
For more information and to reserve promotion space contact
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The
McDonald Report
Commentary & Perspective...
October 20, 2004...We promised a new feature called "Ask Dr. Bob" and we're delivering.
Our first official "Ask Dr. Bob" question came from someone who didn't
quite understand how white LEDs are made, given there's supposedly no such thing
as an inherent "white" LED. So we asked our three Dr. Bobs to collaborate
on an answer, led by Bob Karlicek, Ph.D... the other two Dr. Bobs being Bob
Steele, Ph.D. and Bob Walker, Ph.D., each of whom is an expert in the various
diciplines and markets surrounding advanced LED. Collectively, they have all
the answers. Here's their first report. Most of the work on this one was done by Dr. Bob Karlicek, but Drs. Walker and Steele helped too. Depending on the next up question (and feel free to send one in) the other two might have to do more of the work answering. I thank them all enormously for doing this. By the way, these will eventually be archived over
our technology primers, which are sorely in need of updating. -- JMcD
Dear Dr. Bob, How do you make white LEDs?
Signed, In Need of Enlightenment
Dear In Need,
Simple LEDs make monochromatic light. White light is achromatic (colorless)
and is made by combining light of at least two or more (usually many more) colors.
If white light is made from a careful mix of only two monochromatic colors,
those colors are said to be complementary. The complimentary colors blue and
yellow can be mixed to create what we see as white. Most white LEDs today are
made from blue InGaN LED chips coated with a precise quantity of a phosphor
material that can convert a portion of the blue light from the LED chip into
yellow light. The resulting blend of blue and yellow light is perceived as white.
Some call these LEDs phosphor converted LEDs (PCLEDs).
The phosphor material most commonly used to make white PCLEDs is YAG:Ce because
it absorbs light made by blue LEDs and converts it to a fairly broad (from greenish
to reddish but mostly yellow) emission. YAG is a crystalline material (garnet)
made from yttrium, aluminum and oxygen doped with cerium (which does the light
conversion). While there are many phosphors used in lighting that absorb UV
light (such as those used in fluorescent tubes), there are fewer phosphors that
can convert the blue LED light to longer visible wavelengths with high efficacy
and have the chemical stability to be useable in LED package manufacturing processes.
A lot of research is currently devoted to finding new phosphors with absorption
properties that allow them to efficiently convert light from InGaN LEDs to visible
light.
In LED manufacturing processes, normal variations in the brightness and exact
color LED die and variations in the phosphor coating processes during die packaging
lead to variation in the brightness and the "whiteness" of manufactured
PCLEDs. During final testing, these LEDs are sorted into different intensity
and color bins. Within one intensity bin, some PCLEDs will be a bluer white,
others a yellower white, and so on. LED manufacturers need to find applications
for each of these bins to keep manufacturing costs under control.
Another limitation of many PCLEDs stems from how colorful objects appear when
illuminated by the type of white light they produce. A white light source's
ability to accurately reveal colors depends on the number and intensity of the
colors contained in the light coming from that source. The topic of color rendering
and quantifying various qualities of white light is well beyond the scope of
this short note. For now, let's just say that red or green objects aren't as
vivid when illuminated by PCLED white light made from a mixture of blue and
yellow light. New phosphors that can convert blue LED light to other wavelengths
besides yellow are now being combined with YAG:Ce to improve the color rendering
of blue InGaN PCLEDs.
Another approach to making PCLEDs is to use UV InGaN LEDs and a blend of phosphors
that convert the UV into blue, green and red emission which combine to appear
white. This approach improves color rendering and can reduce manufacturing variability
(range of whiteness) of the light made by the PCLED. Packaging UV LEDs presents
more challenges for some of the packaging materials, including lower reflectivity
of metal surfaces and mold compounds which reduces brightness and photo-degradation
of epoxies and other plastic package parts which reduces LED lifetime. As with
research on phosphors for use with LEDs, research on packaging materials better
suited for use with UV InGaN LEDs is getting a lot of attention.
Combining phosphors with monochromatic LEDs is not the most energy efficient
way to make white LEDs. Phosphors convert higher energy LED light into lower
energy, longer wavelength light and the energy difference is lost as heat in
the phosphor. The energy difference between absorbed and emitted light is called
the Stokes shift. As expected, the Stokes shift is larger (more energy lost
as heat) when UV LEDs are combined with phosphor blends than when blue LEDs
are combined with YAG:Ce, but since UV InGaN LEDs radiate more optical power
than blue InGaN LEDs, both methods make about the same amount of visible light
with a given amount of electrical power (Lumens per watt or Lm/W).
Incandescent lightbulbs produce about 17 Lm/W, and PCLEDs now available in
production are at 25 - 40 Lm/W, with performance as high as 70 - 80 Lm/W demonstrated
in the lab. While these numbers are impressive, cost and incompatibility with
the design of current lighting systems (operating at120/240V AC while LEDs operate
at a few volts DC) will slow the deployment of white LEDs in the field of general
illumination for quite some time with gradual adoption over the next 5 to 10
years or more.
Different color LEDs can also be combined without a phosphor to make a wide
range of colors, including white. The technical challenges and applications
for this approach to making white LEDs is a topic for another report. Hopefully everyone is now "properly enlightned" on how the industry produces white LEDs.
Signed, Dr. Bob
If you have questions about the
solid state lighting and compound semiconductor industries or have news
or views to share, I'm Jo Ann McDonald, Editor of LIGHTimes and CompoundSemi News.
Feel free to contact me directly, anytime. 
My direct tel at the ranch is
+1-325-463-5345
From time to time Jo Ann may comment on companies in which she holds a
modest investment - be sure to read
her disclosure at some point in time... |
