Incandescent Extinction – Which light bulb will win? LED vs. CFL?

The second phase of the US light bulb phase-out hit a major milestone on Jan. 1, 2014, the deadline to end production of 40- and 60-watt incandescent light bulbs. The deadline passed by with not much notice from consumers.  But, the end of incandescent light bulbs sets up a new battle: LED light bulbs vs. CFLs.

Consumer Sentiments

A recent consumer survey by Osram Sylvania, a light bulb manufacturer, measured public attitudes about energy-efficient lighting and awareness in the US.  Here are some of the results:

  • 4 in 10 consumers are aware of the January 2014 phase out of 60W and 40W bulbs
  • More than half (59%) of consumers are excited about the phase out, as it will help Americans use more energy efficient light bulbs.
  • 46 percent of consumers plan to switch to CFLs,
  • 24 percent will opt for LEDs, and
  • 13 percent say that they will choose halogens.
  • This year, 30 percent of consumers say that they plan to buy a lot of traditional light bulbs where still available and will continue using them.
  • This is a sharp increase from the 2012 Socket Survey which showed just 16 percent said that they plan to stockpile bulbs.

Light Bulb Wars

Consumers still have time to make up their minds about their next light bulb because retailers still have supplies of 40- and 60-watt incandescent light bulbs on the shelves.  Retailers like Home Depot and Lowes have enough stock on the incandescent bulbs for consumers through the spring at least.  However, once the supplies dwindle, what should you buy? LED or CFL?  Let’s compare.

CFLs

A descendant of traditional fluorescent lights, compact fluorescent light bulbs (CFLs) contain argon and mercury vapor housed within that spiral-shaped tube. The bulbs rely on an integrated ballast to produce an electric current that passes through the mixture of gasses, exciting the gas molecules that produce the light.  The time for the ballast to produce the electrical current causes that typical CFL delay when it is turned on.  CFLs use 20-30% less energy than the typical incandescent and last about 9.1 years.  Of course, they do contain mercury, so cleaning up after breaking them and disposing of CFLs after they burn out becomes problematic.  Here’s a link to how to dispose of CFLs safely for you and the environment.

LED light bulbs

Unlike traditional incandescent bulbs, LED light bulbs generate light using a small “package” of several LEDs in a light bulb.  LED light bulbs are more efficient since they use a semiconductor to emit light or photons when electricity is passed through it.  LED light bulbs give off more than 80% of the energy used as light. The good news is that LED light bulbs can cut household energy use by as much as 80% and have a lifetime of as much as 22.8 years, about 2.5 times longer than CFLs.

So what do you choose?

Here’s a quick look at some of the LED and CFL light bulbs available on Homedepot.com (pricing as of 1/8/2014).  While Cree and Philips LED bulbs are a bit more expensive for a single bulb, they do produce a soft white light comparable to CFLS and traditional incandescent, but they last much longer.  If you are looking to save energy, you’ll want to know how efficient they are.  You’ll see this in the chart in the column lumens per watt.  This is a measure of how well the light source produces light.  The higher the number, the better your light bulb is at producing light.  Visit your local retailer to see how they look in person, since tastes vary.  For an explanation of the Color Rendition Index, read this previous post.

A Comparison Guide to LED and CFL Light Bulbs

A Comparison Guide to LED and CFL Light Bulbs

For Further Reading

Fox Business, Retailers Brace for Change Ahead of Incandescent Bulb Ban, http://www.foxbusiness.com/industries/2013/12/31/retailers-brace-for-change-ahead-incandescent-bulb-ban/

Osram, Sylvania Socket Survey, http://www.sylvania.com/en-us/tools-and-resources/surveys/Pages/socket-survey.aspx

NBC News, Majority of Americans still in the dark about incandescent light bulb phase-out, http://www.nbcnews.com/technology/majority-americans-still-dark-about-incandescent-light-bulb-phase-out-2D11805991

NBC News, With incandescents dead, smart bulbs step into the light, http://www.nbcnews.com/technology/incandescents-dead-smart-bulbs-step-light-2D11869426

Buildings, Incandescent Bulb Phase-Out Myths Debunked, http://www.buildings.com/news/industry-news/articleid/16806/title/incandescent-bulb-phase-out-myths-debunked.aspx

Newsday, Light bulb shopping choices under new ban, http://www.newsday.com/business/lightbulb-shopping-choices-under-new-ban-1.6706464

Clearlysapphire.com, Confused about Your Home Lighting? – LED, CFL and Incandescent Compared, http://blog.clearlysapphire.com/?p=492

Large Diameter Patterned Sapphire Substrates Explained

Rubicon Technology offers large diameter PSS in a range range of shapes including cone, dome and pyramid as well as custom.

Rubicon Technology offers large diameter PSS in a range of shapes including cone, dome and pyramid and range of orientations.

While LED chip manufacturers have been using patterned sapphire substrates (PSS) for years, there’s growing interest in large diameter PSS.  Recently, Rubicon Technology announced the commercial availability of large diameter PSS.  During their latest earnings call, they indicated that they’ve received interest from 7 major LED chip manufacturers for 4- and 6-inch large diameter PSS.  Why the interest from LED chip manufacturers?

First, PSS helps improve epitaxial growth by promoting growth of the GaN in parallel to the substrate surface. This also helps reduce the number of dislocations, called the dislocation density, which can degrade performance of an LED.  Secondly, patterning can help extract as much as 30 percent more light from an LED.  This is particularly advantageous for high brightness LEDs (HB LEDs) that are used in LED lighting applications.

Second, the evolution of patterning large diameter substrates brings economical advantages to LED chip manufacturers, especially those anticipating demand from the LED lighting market.  Large diameter sapphire wafers help LED chip manufacturers cut costs by enabling more throughput for each run of the MOCVD reactor.  This helps chip manufacturers make better use of the reactor “real estate” and decreases the cost per unit of area processed because of the curvature of the larger wafer.  The outer curvature of a 6-inch wafer is less, enabling greater use of the surface area than the tighter curvature of a 2-inch wafer resulting in less edge loss.  Larger diameter wafers also provide post-MOCVD efficiencies.  Depending on the type of MOCVD reactor used, LED chip manufacturers using six-inch wafer platforms may achieve up to 48% greater usable area per reactor run compared with two-inch wafers.  These efficiency gains become very compelling when manufacturers want to ramp up LED chip production to support greater volumes of LEDs for light bulbs.

Finally, LED chip manufacturers have been buying smaller 2-inch and 4-inch PSS from outside suppliers for years.  The next step in the evolution in the market is the migration to large diameter PSS for the reasons we mention above.  While some LED chip manufacturers will have specialized patterning needs and the resources to keep the work in-house, others will not.  Some LED chip manufacturers may not have the expertise and equipment to move to large diameter PSS, so having a ready, trusted supplier will prove handy.

For Further Reading

ClearlySapphire, LED Lighting Spotlight: Patterned Sapphire Substrates http://blog.clearlysapphire.com/?p=390

Semiconductor Today, Patterned sapphire for nitride enhancements, http://www.semiconductor-today.com/features/SemiconductorToday_SeptOct_PatternedSapphire.pdf

Compound Semiconductor, New Wet Process For LEDs On Patterned Sapphire Boosts Efficiency, http://www.compoundsemiconductor.net/csc/news-details.php?cat=news&id=19734296

Compound Semiconductor, Rubicon Orders Multiple Profilers For Sapphire Production, http://www.compoundsemiconductor.net/csc/news-details.php?cat=news&id=19735318

Clearlysapphire.com, Larger Wafers, Larger Yield – The Numbers Behind Large Diameter Sapphire Wafers and Yield, http://blog.clearlysapphire.com/?p=435

Back to School with More LEDs

New LED Scoreboard at Allen High School, Allen, Texas

New LED Scoreboard at Allen High School, Allen, Texas

With most American students returning to school, we’ve put together a look at two schools that are taking advantage of LED lighting to save money and improve the learning environment.

Special Ed

LED lighting in special education classrooms creates a better learning environment.  The buzzing and flickering from fluorescent fixtures often bother or distract special education students.  Administrators from Cherokee Elementary School in Scottsdale, Arizona believe that LED light fixtures will help students focus more, particularly special education students.

With the help of MaxLite, Cherokee Elementary School replaced 69 2’x4’ fluorescent fixtures with 60 2’x2’ Direct Lit LED Flat Panels in four classrooms.  The move will save nearly 60 percent in energy consumption, plus reduce maintenance costs since the panels are designed to last 50,000 hours or up to 13 years.  In addition, the school received utility rebates for the energy conservation measures to help offset the cost of the lighting retrofit.

Extreme Stadium at Allen High School in Allen, Texas

Texans famously like their football, especially high school football.  Perhaps the most ambitious high school football stadium is in Allen, Texas.  Approved by voters in 2009, Allen High School set out to construct one of the largest high school football stadiums in the US.  Opening for the 2012 season, “Eagle Stadium” at the suburban Dallas high school features 18,000 seats (the band is 675 members alone), NaturalGrass Matrix turf, a 75-by-45 foot HD video scoreboard from Daktronics (that includes LEDs), a weight room, a press room and private boxes that rival some college football stadiums.  The new stadium worked, the Eagles were the 5A State Champions in 2012 with a record of 15 – 1.

For Further Reading

MaxLite, LED Lighting Helps Nurture Better Learning Environments for Special Ed. Children, http://www.maxlite.com/resources/CaseStudyGraphics/MaxLite_Cherokee.cs.20121023.pdf

The Huffington Post, Allen Eagle Stadium, New $60 Million High School Football Venue, Debuts In Dallas Suburb (PHOTOS), http://www.huffingtonpost.com/2012/08/08/dallas-suburb-unveils-new_n_1756434.html

Clearlysapphire.com, LED Lighting Goes Back-to-School, http://blog.clearlysapphire.com/?p=260

LEDs in Action – Performance Art and Fish Bellies

Now that the summer is nearly over (in the US), we thought we might take a look at some fun applications of LEDs including performance art, art turned into football replays, and fish bellies.

Eugene, Oregon-based fiber optic toy company Ants On A Melon, has turned LEDs into performance art. Founded in 2012, the folks at Ants On A Melon have developed an artistic platform designed to share interactive fiber optic artwork.  Their LED performance art using jellyfish is just one example of what they can do with LEDs. You can see a video of the Jellyfish (pictured below) here.

Ants On A Melon, Jellyfish, Performance Art

Ants On A Melon, Jellyfish, Performance Art

 

 

 

 

 

 

The Dallas Cowboys new stadium, AT&T Stadium, is filled with art, including a new LED-based exhibit by LED artist Jim Campbell, “Exploded View (Dallas Cowboys) 2013.”  Exploded View features 2880 LED’s that flicker and illustrate plays in LED lights. A renowned LED light artist, Campbell specializes in low-resolution images.  From close up, the image is completely abstract, but from far away, the football play is recognizable. While we don’t have a video of this artwork, here’s a link to a video of Campbell’s Exploded View, Commuters.

Campbell’s artwork is included in the permanent collections of the Museum of Modern Art in New York, the Smithsonian American Art Museum in Washington, D.C., and the de Young Museum in Golden Gate Park in San Francisco.

Jim Campbell's Exploded View, Dallas Cowboys

Jim Campbell’s Exploded View, Dallas Cowboys

 

 

 

 

 

 

 

While not performance art, the new LED art exhibit at Texas State University, San Marcos River in San Marcos, Texas, by public art designers Joe O’Connell and Blessing Hancock encourages interaction.  Designed to celebrate the biodiversity of the San Marcos River, Fish Bellies enables students to sit inside, study or talk while touch controls allow them to adjust the color and saturation levels of the LED lighting inside.

Fish Bellies at Texas State University, San Marcos River

Fish Bellies at Texas State University, San Marcos River

 

 

 

 

 

 

 

For Further Reading

The Dallas News, LED artist has created the 50th piece in the Cowboys Stadium collection, http://www.dallasnews.com/entertainment/columnists/michael-granberry/20130427-led-artist-has-created-the-50th-piece-in-the-cowboys-stadium-collection.ece

Inhabitat.com, LED Fish Bellies Celebrate Biological and Human Diversity in Texas, http://inhabitat.com/led-fish-bellies-celebrate-biological-and-human-diversity-in-texas/

Benefits of LED Lighting for Cows and Bees

CowsMany industries are looking at using LEDs, but researchers may have found some unexpected benefits of LED lighting for cows and bees.

Iowa Farmer Today reported that dairy cows produce more milk with LED lighting.  While it is still early, a 2010 Oklahoma State study comparing LED lighting to traditional light in dairies resulted in a 6% bump in milk production for the cows exposed to LED lighting.

The experiment compared a 500-cow free-stall barn outfitted with LEDs on one side and traditional metal halide lighting on the other.  Researchers found that cows responded positively to LED light with increased milk production.  Researchers observed that the directional light from LEDs provided the cows with a boost in feed intake.  The researchers don’t know if the increase in milk production is from the feed intake itself, or a possible increase in hormones that promote milk production. In order to prove that LED light increases milk production researchers will need to study further.  They’ll need to determine the effects of increased light, intensity and other variables as well as replicate the study at different facilities.

Pollination by bees is a necessary part of growing flowers and crops.  But bumble bees suffer from poor vision and sensitivity to certain wavelengths of light. In fact, northern climates have shorter growing seasons in part due to the lack of available natural light for pollinator bumble bees.  Use of artificial light sources in horticulture has been an issue due to the bumble bee’s limited vision under UVB, blue and green light.  Finding an artificial light source that works with pollinator bees will help horticulture in areas with limited natural light.

LED grow-light manufacturer Valoya demonstrated the functionality of their lights in a tomato trial at PlantResearch in Made, Netherlands.  The company compared pollinator bee activity in two compartments: one with LED lighting and another with only natural light. The bees in the LED compartment started flying out to flowers immediately when the AP67-LED lights were turned on.  The bees in compartments with high pressure sodium lights on (and an open hatch) only started to move 4 hours later when some natural light became available through the open hatch.  More study is needed, but LED-grow lights may prove effective to increase pollination time in areas with limited amounts of natural light.

For Further Reading

Iowa Farmer Today, Milking lighting to boost production, http://www.iowafarmertoday.com/news/dairy/milking-lighting-to-boost-production/article_4b824b94-028a-11e2-8a2d-001a4bcf887a.html

Valoya Press Release, Valoya’s Horticultural LED Lights Enable Pollinator Bees to Operate without Natural Light, http://www.valoya.com/document-repository/press-releases/document/valoyas-horticultural-led-lights-enable-pollinator-bees-to-operate-without-natural-light?format=raw

LEDs Magazine, Valoya claims additional benefits for LEDs in horticulture, bees like SSL, http://ledsmagazine.com/news/10/6/13

How Do They Do It? From Sapphire to LED Infographic

You’ve heard a lot about LEDs, but did you know that a tiny piece of sapphire – the pure, colorless industrial variety, not the blue gemstone – is in more than 80% of LEDs? Sapphire is the foundation for the LED chip, just as silicon is for a computer chip.  Rubicon Technology has put together an infographic that describes the sapphire manufacturing process and where sapphire is found in an LED. The bottom of the infographic features examples of products that feature LEDs for lighting. Click on the infographic below to see it larger.

Infographic for Post

 

 

 

 

 

Link to: http://www.rubicontechnology.com/sites/default/files/From%20Sapphire%20to%20LED%20Infographic.pdf

Larger Wafers, Larger Yield – The Numbers Behind Large Diameter Sapphire Wafers and Yield

rubicon-waferyield-540x720-3Today, more than 80% of LEDs are based on sapphire substrates. For years, two-inch and four-inch diameter sapphire wafers have been the standard for LED production.  Now, LED chip manufacturers are looking to migrate to six-inch diameter wafers to increase the yield or the amount of LED chips they can make out of each wafer.  This is important as new market opportunities like LED-based general lighting take off, demanding more sapphire.

Rubicon put together an infographic, Larger Wafer, Larger Yield, about the yield from large diameter wafers. You can see it here on Rubicon’s new web site:  http://www.rubicontechnology.com/sites/default/files/Rubicon_WaferYield_v3.pdf

Rubicon Technology’s CEO Raja Parvez talked about the benefits of moving to large diameter sapphire wafers in an article, Vertical Integration Streamlines Sapphire Production, in Compound Semiconductor earlier this year.

According to Parvez, LED chip manufacturers look to large diameter sapphire wafers to cut costs.  Large diameter sapphire wafers enable more throughput for each run of the MOCVD reactor, making better use of the reactor “real estate” and decreasing the cost per unit of area processed.  The outer curvature of the 6 inch wafer is less, enabling greater use of the surface area than a 2 inch wafer resulting in less edge loss. In addition, large wafers provide post-MOCVD efficiencies.  Depending on the type of MOCVD reactor used, LED chip manufacturers using six-inch wafer platforms may achieve up to 48% greater usable area per reactor run compared with two-inch wafers.  These efficiency gains become very compelling when LED chip production ramps up in large volumes to support a high growth market like general lighting.

For Further Reading

Compound Semiconductor, Vertical Integration Streamlines Sapphire Production http://www.compoundsemiconductor.net/csc/features-details.php?cat=features&id=19736275&key=rubicon%20technology&type=

Top 9 Things You Didn’t Know about LEDs

Philips Luxeon LED

Philips Luxeon LED

Recently, the Department of Energy published a list of the Top 8 Things You Didn’t Know about LEDs. We’d like to share the list, and add one more for our Clearlysapphire blog post this week.

9.  Sapphire is the base material for more than 80% of LEDs, just like silicon is the base material for computer chips.

8. A light-emitting diode, or LED, is a type of solid-state lighting that uses a semiconductor to convert electricity into light. Today’s LED bulbs can be six-seven times more energy efficient than conventional incandescent lights and cut energy use by more than 80 percent.

7. Good-quality LED bulbs can have a useful life of 25,000 hours or more — meaning they can last more than 25 times longer than traditional light bulbs. That is a life of more than three years if run 24 hours a day, seven days a week.

6. Unlike incandescent bulbs — which release 90 percent of their energy as heat — LEDs use energy far more efficiently with little wasted heat.

5. From traffic lights and vehicle brake lights to TVs and display cases, LEDs are used in a wide range of applications because of their unique characteristics, which include compact size, ease of maintenance, resistance to breakage, and the ability to focus the light in a single direction instead of having it go every which way.

4. LEDs contain no mercury, and a recent Energy Department study determined that LEDs have a much smaller environmental impact than incandescent bulbs. They also have an edge over compact fluorescent lights (CFLs) that’s expected to grow over the next few years as LED technology continues its steady improvement.

3. Since the Energy Department started funding solid-state lighting R&D in 2000, these projects have received 58 patents. Some of the most successful projects include developing new ways to use materials, extract more light, and solve the underlying technical challenges. Most recently, the Energy Department announced five new projects that will focus on cutting costs by improving manufacturing equipment and processes.

2. The first visible-spectrum LED was invented by Nick Holonyak, Jr., while working for GE in 1962. Since then, the technology has rapidly advanced and costs have dropped tremendously, making LEDs a viable lighting solution. Between 2011 and 2012, global sales of LED replacement bulbs increased by 22 percent while the cost of a 60-watt equivalent LED bulb fell by nearly 40 percent. By 2030, it’s estimated that LEDs will account for 75 percent of all lighting sales.

1. In 2012, about 49 million LEDs were installed in the U.S. — saving about $675 million in annual energy costs. Switching entirely to LED lights over the next two decades could save the U.S. $250 billion in energy costs, reduce electricity consumption for lighting by nearly 50 percent and avoid 1,800 million metric tons of carbon emissions.

For Further Reading

Department of Energy, Top 8 Things You Didn’t Know about LEDs, http://energy.gov/articles/top-8-things-you-didn-t-know-about-leds

Lightfair 2013 – Observations about LEDs from Philadelphia

The LFI Innovation Award went to Philips BoldPlay  for Most Innovative Product of the Year

The Lightfair International trade show and conference was recently held in Philadelphia.  According to the organizers, LIGHTFAIR International (LFI) is the world’s largest annual commercial and architectural lighting trade show and conference.  Sponsored by the Illuminating Engineering Society (IES) and the International Association of Lighting Designers (IALD), the 2012 show had more than 24,000 registered attendees from 73 countries. It is clearly a big deal in the lighting industry.

Here’s a round-up of some analysis of LEDs at the show and a quick look at industry awards from LFI.

The engineers from Groom Energy made their annual trek to Lightfair and included an analysis of their trek in their blog.  This year, they noticed a difference in the quality of light from LEDs on display.  The light the LEDs on display put off was the more familiar, warmer light similar to the light put out by an incandescent. LEDs also got smarter with lighting controls evolved from being add-ons to being embedded. Jon Guerster, the author of the blog, speculates that California’s Title 24 that requires lighting controls may be a driver for all of the new smart lighting controls.  Finally, the Groom Energy team found that LED fixtures no longer looked distinct like LED fixtures, but sported the familiar look of incandescent, HID and fluorescent fixtures from the past. Now, you can’t tell that there are LEDs inside.

The LED analyst team from IMS Research traveled from London to Philadelphia and posted an analysis about the show on their LED blog.  IMS Analyst Jamie Fox noted that the show no longer featured that “Wow” moment.  He said this is due to the relative maturity of LED lighting.  The maturity and evolution of the LED market also led to two key observations from IMS.

According to Fox, there’s no clear winning sector in the American LEDs general lighting market.  Fox and his colleagues were told by LED manufacturers that residential, retail, outdoor, hospitality and others all have a “significant” part of the pie but none of them dominates. This was supported by IMS observations of the product mix on the show floor.  As for LED manufacturers, Fox noted that the “big three” — Nichia, Cree and Lumileds — are leaders in the American LED market and while global LED players like Samsung, Seoul Semiconductor, Osram and others play a role in the US, the “big three” are consistently mentioned as clear leaders in the market.

Finally, Fox noted that industry price decreases versus quality was an issue for many at the show.  According to Fox, “there is a significant worry though, both from my own observations of product, and from show floor conversations, that it is becoming too much of a lowest price fight at the moment, and not enough advancement on quality.”  Fox says low price may not ensure that a customer will be happy with the light quality from an LED bulb that doesn’t compare well to an incandescent bulb.

The LFI Innovation Awards program honored lighting vendors for innovation and design. Here are a few of the top winners:

  • PHILIPS (BoldPlay): Most Innovative Product of the Year—the program’s highest award, recognizing the most innovative new product
  • COOLEDGE LIGHTING (Light Sheet): Design Excellence Award—recognizing outstanding achievement in design
  • DOW CORNING CORPORATION (Dow Corning® Brand Moldable Silicones): Technical Innovation Award—recognizing the most forward-thinking advancement in lighting technology
  • PHILIPS (hue personal wireless lighting): Judges’ Citation Award—special recognition of an innovative product at the judges’ discretion

For Further Reading

Groom Energy, LightFair 2013: LED Lighting Is Warm, Smart and Looks Like What You Know, http://blog.groomenergy.com/2013/04/lightfair-2013-led-lighting-is-warm-smart-and-looks-like-what-you-know/

IMS RESEARCH, LED Blog, LEDs Continue to Evolve At LIGHTFAIR, http://www.ledmarketresearch.com/blog/leds_continue_to_evolve_at_lightfair

LED Lighting Spotlight: Patterned Sapphire Substrates

In the ongoing quest to make LEDs more efficient, LED chip manufacturers have developed patterned sapphire substrates (PSS).  In fact, most high-brightness LEDs are made using PSS. There are very few resources online that explain patterned sapphire substrates. Here’s a brief explanation.

PSS helps extract more light from LEDs.  A lot of light bounces back into the LED when using a polished sapphire substrate.  Researchers discovered that patterning the surface of the substrate by etching nano-scale patterns helps more light, in the form of photons, escape, improving the light generated or extracted by the LED.  It is reported that patterning can improve the extraction of light by as much as 30%.

A second important point is that patterning also improves the epitaxial growth process.  The nano-patterned surface can have a positive effect on the nitride semiconductor growth process by promoting growth of the GaN in parallel to the substrate surface, called lateral growth.  This also helps reduce the number of dislocations, the dislocation density, that can degrade performance.

LED chip manufacturers originally developed PSS.  The patterns are quite proprietary and helped the LED chip companies differentiate themselves.  Today, the sapphire industry has joined in and sapphire wafer manufacturers have begun to put patterns on sapphire wafers in partnership with the LED chip manufacturers. The patterning work is concentrated with smaller wafers in the 2 to 4-inch diameter range, but manufacturers of large diameter wafers like Rubicon Technology are beginning to develop PSS for larger wafers.

Most patterning is based on a proprietary design from the LED chip manufacturer.  The patterns can vary from cones, pyramids and flat tops and can be organized in hexagonal or trigonal patterns.  Some basic design rules based on height and height/pitch ratio have emerged, but so far, no standards exist.  Currently the most popular pattern is a cone shape, but these patterns change frequently.  Here are some sample patterns.

Sample patterns:

Sample patterns for PSS

 

 

 

 

 

 

 

Sample Pattern for PSS

 

 

 

 

 

 

For Further Reading

Semiconductor Today, Patterned sapphire for nitride enhancements, http://www.semiconductor-today.com/features/SemiconductorToday_SeptOct_PatternedSapphire.pdf

Compound Semiconductor, New Wet Process For LEDs On Patterned Sapphire Boosts Efficiency, http://www.compoundsemiconductor.net/csc/news-details.php?cat=news&id=19734296

Compound Semiconductor, Rubicon Orders Multiple Profilers For Sapphire Production, http://www.compoundsemiconductor.net/csc/news-details.php?cat=news&id=19735318