Nanoscale Patterning: The Future of PSS

As the adoption of patterned sapphire substrates (PSS) continues to rise in the LED industry, the time is now to look ahead to new ideas and theories that have the potential to further advance LED lighting. In particular, recent research surrounding nanoscale patterning proves it has promising applications in the LED industry’s future.

But before diving into new patterning processes, how is PSS currently benefiting the industry?

PSS Today

Etching a pattern directly on to a sapphire substrate increases light extraction, allowing LED manufacturers to create the brightest possible LED lights. There are two main ways patterning can increase the light output of an LED:

1) Patterning promotes lateral growth of the epitaxial layers, reducing epitaxial defect     density, thereby increasing the amount of light emission of active quantum well layers.

2) Patterns help scatter the photons that are emitted, effectively expanding the light           escape cone and increasing total internal reflection, or TIR, and creating a brighter light.

In these ways, patterned substrates contribute to greater light extraction efficiency.  Additional manufacturing efficiencies are available with larger diameter substrates in the form of reduced edge loss, less wafer handling, and potentially greater throughput with each reactor cycle, furthering LED chip manufacturers’ objective of increased lumens per dollar.

How are they made?

To create effective PSS, the structures, which can be in the shape of a cone, dome or pyramid, need to be accurately and uniformly etched. Currently, there are two manufacturing processes that are used to fabricate PSS:

1) Dry plasma etching, the process used for the majority of PSS today because of its greater control of precision and uniformity.

2) Wet chemical etching, which is more scalable and faster than dry plasma etching but produces LEDs that are less effective and efficient.

Great precision is required to maintain uniform patterning over a larger surface; therefore dry plasma etching is the processed used for large-diameter PSS.

Rubicon Blog PhotoWhat’s next?

Research shows that nanopatterning has the potential to be even more efficient than current micro-patterning practices.

Academic researchers have extensively studied nanopatterned substrates to evaluate their potential impact on light extraction efficiency and internal quantum efficiency. The results are extremely promising, as several reports show that LEDs built on nanopatterned substrates produce a significant further increase in luminous efficiency compared with micropatterns.

While it will still be some time before we see nanopatterning used in commercially available LEDs, nanopatterning is an exciting development that shows great promise for the future of LED efficiency.

Sapphire Industry Watch – March 27

  • Disco Dog smartphone-controlled LED vest makes your dog a party animal – Slashgear: New York creative firm PARTY has invented a LED covered vest for dogs – dubbed Disco Dog – that can be controlled by a smartphone via Bluetooth to display animated patterns of light. In addition to making a dog the life of the party, the vest has additional safety features, such as the option to automatically update the vest with a scrolling message of “Lost Dog” if the pup runs out of range.
  • Aerial fire truck add-ons to boost function – Fire Chief: LED technology is being used on aerial fire trucks to improve visibility and scene safety. Manufacturers are installing LED rope lights on both sides of ladders to better illuminate the path to the building, making it safer for personnel climbing the ladder and easier for the turntable operator to see where the ladder is during low visibility conditions.
  • This Millennium Falcon paper model looks real enough to fly – CNET: After four years of tedious assembly, Polish artist and self-proclaimed “Star Wars” fan Bernard Szukiel debuted his paper model of Hans Solo’s legendary ship, The Millennium Falcon, at the “Star Force” exhibition in Torun, Poland earlier this month. Measuring at 38 inches, the model was built using only paper, thin cardboard, a few wires, clamps, optical fibers and LED lights. The LEDs allow the model to light up like in the original movie.
  • Rubicon showcasing large-diameter patterned sapphire substrates for LED market – Semiconductor Today: Rubicon Technology showcased its large-diameter patterned sapphire substrates as well as its line of 4” and 6” polished sapphire wafers for the LED industry at LED Taiwan 2015. With an edge exclusion zone as small as 1mm, Rubicon offers LED chip makers more usable area to maximize the number of chips per wafer. LED Taiwan 2015 was held in Taipei from March 25-28.

Sapphire Industry Watch – March 20

  • Railroad bridge offers rainbow of lights – The Leaf-Chronicle: The RJ Corman Bridge in Clarksville, TN has been given a much need facelift with the thick rust that once covered its exterior being replaced by coats of historic silver paint and the installation of 104 individual groups of LED lights. Each group of lights is made up of an array of red, green, blue and white LEDs and can be programmed to display almost any color.
  • Orlando entrepreneurs create night lights for runners – Orlando Sentinel:  An Orlando couple has launched a Kickstarter campaign for their invention of LED lights that mount of runner shoes, called “Night Runner Shoe Lights”. Essentially LED lights that clip onto a runner’s shoe, the devices can light a path up to 30 feet ahead of the runner, allowing them to see more clearly at night.
  • Stunning video shows people surfing at night with LED surfboards and wetsuits – Business Insider:  As part of an upcoming surf film they’re producing titled “Invasion”, French production company Band Originale filmed professional surfers Axi Munian and Jerome Sahyoun surfing on LED outfitted surfboards and wetsuits at night off the Moroccan Coast.
  • LED street lights conversion coming to more areas of San Jose – Spartan Daily: San Jose’s LED conversion program, which has already converted a total of 3,400 low-pressure sodium bulbs to LEDs, is showing savings, with the lights tested saving 40-60 percent more electricity compared to the old bulbs. Along with energy savings, the new lights are giving city engineers more control over lighting by allowing them to regulate usage and control individual lights from a central location.

What is the strongest natural material on Earth?

Materials like sapphire, diamond, Kevlar and even spider silk are all well-known for their incredible strength.

Now there’s a new entrant into the conversation, and forgive them for being a bit late—they are snails, after all.

A recent scientific study published in the Journal of the Royal Society Interface has declared limpet teeth as the new official strongest natural material on earth. For those not up to date on gastropods, limpets are small sea snails that live in both fresh and salt water and use their super strong teeth to scrape food off rocks.


We’re talking tensile strength here, not hardness.  Hardness and tensile strength are fairly different. A simplification would be that hardness is a resistance to scratching while tensile strength reflects a resistance to breaking.

What is it about limpet teeth that make them so strong?

The tiny teeth are made of very thin, tightly-packed fibers that contain the hard mineral goethite. At 1/100th the diameter of a human hair, the ultra-thin fibers create an almost flawless weave that trumps even man-made carbon fibers.

As the author of the study Professor Asa Barber of The University of Portsmouth put it:

“Generally a big structure has lots of flaws and can break more easily than a smaller structure, which has fewer flaws and is stronger. The problem is that most structures have to be fairly big so they’re weaker than we would like. Limpet teeth break this rule as their strength is the same no matter what the size.”

To gauge the fibers’ tensile strength, Professor Barber attached each end of a small piece of the material to a lever and pulled on the sample until it broke. He found that the material had a strength of 5 gigapascals, which is five times the strength of spider silk and even beats out Kevlar. The tensile strength in this case comes primarily from the structure at a macroscopic level, not the same as crystal structure, which is molecular.

In the future, Professor Barber hopes to see the fibrous structures of limpet teeth studied and used by engineers for high-performance applications, such as Formula One race cars and boat hulls.

Until then, the team at Rubicon gives limpets a tip of the hat for having teeth made of the strongest natural material on Earth.

Stephen Colbert

Sapphire Industry Watch – March 13

  • Rubicon CEO Discusses Applications for Sapphire – NBC 5 Chicago: Bill Weissman, CEO of Rubicon Technology, discusses current uses of sapphire in every day applications such as LED lighting and mobile applications, as well as more unique uses like invisible braces and high-end razor blades. As Rubicon continues to experiment with ways to bring sapphire manufacturing costs down, there is enormous potential for new and exciting applications of sapphire in the future.
  • Are LEDs About to Take Over the World? – The Huffington Post UK: Although the first LED light was produced in 1962, it wasn’t until recently that increased sustainability efforts and lowering costs encouraged the widespread adoption of LEDs. From the Empire State Building’s lighting renovation to NASA’s development of LED facials, it is clear we are living in the age of the LED.
  • Auckland’s bridge lit up by 51 thousand bulbs –  In celebration of the city of Auckland’s 175th anniversary, New Zealand’s iconic Auckland Harbour Bridge is being transformed into an interactive art, music and light show for the next six weeks. More than 51,000 LED light bulbs have been synced to music chosen by the public and performances can be watched in-person, and also via live stream on mobile phones and laptops.
  • San Diego School District Uses Prop 39 Funds for Energy Savings – Energy Manager Today: Thanks to $850,000 in funding from Proposition 39, the California Clean Energy Jobs Act, the Del Mar Union School District in San Diego will be replacing current light fixtures with longer-lasting LED light fixtures with occupancy sensors and dimming controls. The school district will also receive a rebate for the LED installations from San Diego Gas & Electric.

Sapphire: The Clear Choice for Military Applications and Beyond

In case you missed it, something BIG is happening in the sapphire industry.

But just what are the practical applications for a massive slab of sapphire?


First and foremost, sapphire is hard, and as a result, extremely durable. On a scale of hardness — the Mohs scale to be exact — sapphire is the second hardest naturally occurring material, next only to diamond.

Sapphire Infographic

This makes sapphire a clear choice over glass for use in harsh environments, such as deserts. Sapphire is harder than quartz (the main component of sand), and does not scratch as easily as glass would, making it ideal for a variety of applications that come in contact with sand. One that comes to mind is the lens of a military-issue scope. Currently, the military is beginning to swap out scopes that have lenses made of glass that scratch easily, in favor of sapphire lenses.

Besides being useful as a lens, sapphire is so hard it can be used as transparent armor — hard enough that it can even shatter a .50 caliber bullet if thick enough. This leaves endless possibilities for its use in tank windows, transport vehicles, etc.


Sapphire can withstand extreme temperatures without losing its integrity, making it ideal for space exploration. Some regions of space get less than I degree C above absolute zero.  On the other hand, during re-entry, NASA says the external surfaces of spacecraft can reach a temperature in excess of 1,500 degrees Celsius. With its ability to withstand extreme high and low temperatures, sapphire is an ideal material for use in the cones of spacecraft.

Along with the ability to withstand extreme temperatures, sapphire is also known for being “radiation hard,” meaning that sapphire does not break down when exposed to radiation. Once astronauts leave the protection of earth’s magnetic field and atmosphere, radiation becomes a concern. Most materials rapidly change chemical properties under radiation exposure, but because sapphire is less susceptible, it is well suited for space exploration.


Oil and Gas

Nasty chemicals and harsh sea air take a toll on glass and metals, but sapphire is chemical-resistant. In the oil and gas industry, harsh chemicals are omnipresent, so tools and machinery need to be able to withstand the effects of exposure. Thanks to its corrosion resistance, sapphire is a perfect material for use in the oil and gas industry, specifically in the harsh remote areas where oil and gas exploration takes place.

Sky's the Limit

For sapphire, the sky’s the limit when it comes to future uses. Whether it is in spacecraft or oil and gas exploration, new manufacturing methods are ensuring that sapphire will be an important material for years to come.

Sapphire Industry Watch – March 6

  • Humble light bulb helps Japan fill nuclear gap – Chicago Tribune: When the Fukushima nuclear meltdown of 2011 resulted in the closure of many of Japan’s reactors, a national campaign was started to reduce energy consumption. Since the start of 2012, 73 million LED light bulbs have been sold in Japan, comprising about 30 percent of all bulbs sold there.  As LED adoption continues to increase, the country is also pursuing alternative energy sources such as solar power to help relieve the pressure caused by the shuttering of its nuclear energy program.
  • Revamped Dubai park to bask in the sunshine – Khaleej Times:  Al Khazan Park – which officially opened to the public on March 2 – has been revamped into Dubai’s first sustainable park. An off-grid solar power system and LED lights will reduce the amount of CO2 emissions annually by 44.5 tons, which is the equivalent to saving 1,100 trees.
  • Europe to have 2.9 bn general lighting LED lamp installations by 2019 – Greentech Lead: According to an ElectroniCast Consultants report, the number of LED lights installed for general lighting in Europe will grow at an average annual rate of 58.7 percent, rising from 288 million in 2014 to 2.9 billion in 2019. The European market is predicted to grow at a slightly faster rate than the U.S. market during the same time frame. Europe is expected to maintain its leadership in relative market share throughout the forecasted period.
  • SF Ferry Building Gets Makeover for World’s Fair Centennial Anniversary – ABC 7: To celebrate the centennial anniversary of the San Francisco World’s Fair, the iconic Ferry Building has been lit up the same way it was when the fair opened in 1915. Only this time the building will be lit up with nearly 1,100 energy efficient LED lights. The lights will stay up through December with two large beacons commemorating the year 1915.

Industry Watch – Sapphire at Mobile World Congress 2015

Although the theme of Mobile World Congress 2015 was expected to revolve around topics like 5G or USB type-C, many were undoubtedly surprised by the prominent presence of luxury items, the majority of which featured sapphire and, of course, LEDs.

Sapphire certainly made a strong name for itself in Barcelona, debuting on consumer electronics such as smartphones and the biggest hit of the show, The Huawei Watch.  These products along with conceptual security glasses proved that the real theme of MWC 2015 was luxury.

How a Chinese smartwatch became the surprise hit of Mobile World Congress – The Verge: During this year’s Mobile World Congress, Huawei unveiled its first smart watch, The Huawei Watch. Designed with a more classical look in mind, the smartwatch’s stainless steel build and sapphire crystal face make it feel like an actual timepiece. The Huawei Watch turned heads during the show and was noted as one of the more surprising stories to come out of this year’s MWC.


AVG camera- confusing glasses fool facial recognition – CNET:  At MWC, security software developers AVG debuted their conceptual privacy glasses, designed to obscure the user’s face when a smartphone camera is pointed at it. Studded with infrared LEDs around the frame, the glasses beam IR light that is invisible to the human eye but has the ability to confuse filters employed by smartphone cameras. As a result, the camera cannot recognize the user’s face to tag the user, disguising one’s personal identity.

Smart Glasses

HTC One M9 First Look: A Focus on Fixes – The Wall Street Journal: The HTC One was deemed the “best Android Phone ever” at last year’s Mobile World Congress; however, it was later criticized for having a subpar “ultra pixel” camera that produced low-quality photos. The new HTC One M9 debuted this year with a 20-megapixel camera with an upgraded sensor and sapphire glass lens to resist scratches.


Even though Mobile World Congress has now come to an end, it is clear that the possibilities for applying sapphire and LEDs in consumer electronics are just beginning.

Sapphire Industry Watch – February 27

  • Electric cars and LED streetlights to help Edinburg meet emissions targets – Herald Scotland: This week, the Edinburgh City Council began considering adoption of the Sustainable Energy Action Plan (SEAP) that aims to reduce carbon emissions 42 percent by 2020. One proposal put forward in the plan is the replacement of street and tenement stair lights with energy efficient LED systems.
  • New branding at Great American Ball Park – WVXU Cincinnati: When the Cincinnati Reds return from spring training, they’ll find new signs at their home stadium, Great American Ball Park. The $1-2 million project was paid for by Great American Insurance Group and will replace three neon signs throughout the park with new LED signage. The LEDs will use less electricity and operation costs will be approximately 80 percent less than the current neon signs.
  • UL researchers LED the way – Clare Herald: Researchers at the Circuits and System Research Center at University of Limerick have received $380,000 in funding from Enterprise Ireland to develop technology that will make LED light-bulbs programmable. The technology will allow homeowners to control the level, tone and even color of light emitted from an LED light-bulb. The research aims to develop ‘smarter’ digital control algorithms to allow for increased functionality, as well as significant savings in energy consumption.
  • This Smart LED Jump Rope Flashes Stats in Front of Your Face – Gizmodo: Smart Rope, an LED-laden jump rope is putting a twist on fitness-tracking. Like a wearable, the jump rope tracks your movements and generates stats, but thanks to the LEDs embedded in the rope, it then displays your stats right in front of your eyes while you’re working out.