Category Archives: LEDs

By Rania Georgoutsakou, director of Public Policy for Europe, SEMI

In a global industry, monitoring regulatory developments across different regions can be a challenge. Add to that the additional complexity of communicating with a (global) supply chain, then consider that each company has to individually reach out to its suppliers and customers. This results in numerous communications on the same issue up and down the supply chain, and the benefits of industry collaboration within associations such as SEMI become clear.

To help companies keep up with the latest developments in the EU, here’s a list of recent and upcoming regulatory initiatives and how SEMI member companies are collectively addressing these:

  • SEMI FAQ – EU F-Gas regulation and semiconductor manufacturing equipment
  • Review of EU Machinery Directive now underway
  • EU PFOA restriction under discussion
  • 2016 EU Blue Guide is available

A SEMI webcast on EU regulatory developments (March 2016) provided a more detailed overview of these and other developments and how companies should prepare – the webcast is available to view for SEMI member companies only, please click here and select the “EU Regulation Webcast”.

Manufacturing equipment containing pre-charged chillers – new SEMI FAQ provides guidance on how to comply with EU F-Gas law

The EU F-Gas regulation that entered into force in January 2014 creates new restrictions on placing on the EU market pre-charged chillers containing certain fluorinated gases (F-gases).

A new SEMI FAQ on the EU F-Gas regulation provides guidance on what this law is about, how it impacts semiconductor manufacturing equipment and what steps companies importing affected equipment should be taking to ensure compliance.

If your company is importing semiconductor manufacturing equipment containing pre-charged chillers into the EU, then you need to make sure you can account for the f-gases in the chiller under the new F-Gas quota system that the law has established, by obtaining an ‘authorisation’ from a ‘quota holder’ and registering in the ‘EU HFC Register’.

For more details and compliance timelines, check out the SEMI FAQ.

EU Machinery Directive – review now underway – have your say!

The EU Machinery Directive sets out the basic requirements machines must satisfy in order to be placed on the EU market and is a major piece of EU law for semiconductor manufacturing equipment.

The review is part of the regular EU regulatory review process to ensure legislation is ‘fit for purpose’ and does not automatically imply that the Machinery Directive will be revised. It is being run by an external consultant and a final report is expected in April 2017.

The focus of the review will be on 9 product categories, including machines for metal working, engines and turbines, robotics and automation and will also explore whether there are discrepancies in the interpretation of the directive between various member states and to what extent it is aligned to other pieces of legislation.

SEMI is putting together a working group to contribute to review of the EU Machinery Directive. If you are a member company and want to get involved, please contact [email protected]

PFOA restriction under discussion – SEMI requests derogations for the industry

The EU is currently drafting a law to restrict the manufacture, use and placing on the market of PFOA, its salts and PFOA-related substances under EU REACH. The restriction would apply both to substances and mixtures and to articles containing these substances.

SEMI has been calling for a derogation for substances and mixtures used in photolithography processes and for articles contained in semiconductor manufacturing equipment.

SEMI has collected and submitted evidence to substantiate members’ recommendations for:

  • a derogation period of at least 10 years for semiconductor manufacturing equipment, to allow equipment manufacturers to communicate with their the supply chain, identify components potentially containing restricted substances, source substitute parts that are tested and validated and requalify the equipment.
  • non-time-limited derogation for spare parts for legacy semiconductor manufacturing equipment, i.e. equipment that was already on the EU market before the restriction entered into force and before the derogation for semiconductor manufacturing equipment expires.
  • non-time-limited derogation for second-hand semiconductor manufacturing equipment, to ensure that companies can still import used equipment from outside the EU or from another EU member state.

SEMI has also voiced its concerns around the proposed concentration limits and the non-availability today of standardized practicable analytical methods that can be applied to a variety of materials to test whether an article would comply with the restriction.

The EU proposed restriction will be published in the next month and the final decision on the restriction is expected by the end of 2016.

Product regulatory compliance in the EU – 2016 Blue Guide now published

The Blue Guide provides guidance on how to implement EU product rules, including for example the EU Machinery and EMC Directives. A 2016 revised version is now available to download – click here.

The Blue Guide addresses:

  • what constitutes placing a product on the EU market
  • obligations of the various actors in the supply chain (manufacturer, importer, authorized representative etc.)
  • product requirements
  • conformity assessment
  • accreditation
  • market surveillance carried out in the EU

For an overview of SEMI’s advocacy work in Europe, please click here.

To find out more and get involved, please contact [email protected]

Join us for the 10th SEMI Brussels Forum – the industry’s major annual event bringing together company executives and decision-makers to discuss opportunities for the micro/nano-electronics industry in Europe: www.semi.org/BrusselsForum

Dow Corning will present an exclusive glimpse of upcoming products and technologies at LIGHTFAIR International 2016 (Booth #3657), and showcase new advances in LED lamp and luminaire lighting that its broad commercial portfolio of cutting-edge optical silicone solutions are enabling worldwide.

“Three years ago, Dow Corning’s optical silicones technology sparked a surge of breakthrough innovations in LED lighting designs, and the demand for these uniquely advanced materials has only grown as the industry seeks to maintain the momentum they have helped build,” said Hugo da Silva, global industry director for LED lighting at Dow Corning. “Dow Corning is as committed as ever to working closely with customers to expand on their early successes, and formulate new optical silicone solutions to help them usher in the next-generation of LED illumination.”

Dow Corning will offer an early glimpse at LIGHTFAIR 2016 of at least one of those upcoming optical silicone solutions – Dow Corning MS-4002 Moldable Silicone. Planned for launch later this year, this high-performing material signals the latest advance in the company’s award-winning Moldable Silicone portfolio. Currently in development and testing, MS-4002 Moldable Silicone aims to offer the optimum balance of material toughness for reaching high IP and IK ratings, high light transmittance rate and smooth surface feel for secondary optics in LED lamp and luminaire applications for both indoor and outdoor.

As the global leader in silicone innovation and technology, Dow Corning is changing the game for LED design, and the company will show exactly how during LIGHTFAIR 2016. The booth will feature the company’s broad and growing range of proven solutions at three corner kiosks, focusing on:

  • Dow Corning Moldable Silicones, where visitors can explore how these materials are delivering proven solutions for enhancing the optical quality, efficiency and reliability of lamp and luminaire designs
  • Protection & Assembly Solutions, where customer products illustrate how Dow Corning’s innovative silicone protection, assembly and optical solutions have helped develop products with longer life cycles and greater efficiency in outdoor/architectural, interior/specialty, display and automotive lighting applications
  • Silicone-Enabled Designs demonstrating new ways to shape, direct and diffuse light more efficiently with Dow Corning Optical Silicones. Visitors can also explore how silicone materials have expanded innovative design possibilities as LumenFlow Corp. takes them step by step through the LED design ideas process

In addition to offering an exclusive sneak peek at upcoming technologies, Dow Corning Lighting experts will be on hand to discuss the unique design flexibilities, proven reliability and simpler processability enabled by Dow Corning’s optical silicones. A market leader in materials, expertise and collaborative innovation for LED lighting concepts, Dow Corning offers solutions that span the entire LED value chain, adding reliability and efficiency for sealing, protecting, adhering, cooling and shaping light across all lighting applications.

LIGHTFAIR International is the world’s largest annual architectural and commercial lighting trade show and conference. Held at San Diego’s Convention Center from April 26-28, this year’s edition is expected to attract over 28,000 design, lighting, architectural, design, engineering, energy, facility and industry professionals from around the world to set future trends for lighting, design and technology innovation.

Leading innovators in today’s integrated electronics supply chain are preparing to showcase their products and services at SEMICON West 2016 on July 12-14 in San Francisco, Calif.  Attendees will discover new international partners and suppliers, learn about the latest start-ups, and view cutting-edge, critical manufacturing technologies.

The industry has seen dramatic changes since last year’s exposition. Consolidation, IoT, and system integrators increasingly calling the shots have transformed the landscape. Engaging customers and finding new ones have never been more important. SEMICON West 2016 reflects this major realignment — it’s not “business as usual” anymore.

The expanded show floor has been re-engineered to feature megatrend programs and displays, including: the Innovation Theater and four new Exhibit Zones — Advanced Substrate Engineering, Advanced Packaging, Sustainable Manufacturing, and 3D Manufacturing. International Pavilions include Europe, Silicon Saxony, and Malaysia.

SEMICON West 2016 also features three new forums: Advanced Manufacturing, Flexible Hybrid Electronics, and the World of IoT.  Popular recurring programs include the SEMI/Gartner Market Symposium, “Bulls & Bears,” Connect Executive Summit, plus forums addressing wearables, Big Data, mobile, automotive, and other areas of interest to players in these supply chains.

SEMICON West 2016 will attract a broader roster of market makers in today’s globally interconnected semiconductor supply chain, including many of the world’s leading electronics companies as well as their customers and suppliers. To exhibit, visit: www.semiconwest.org.

The 62nd annual IEEE International Electron Devices Meeting (IEDM), to be held at the San Francisco Union Square Hilton hotel December 3 – 7, 2016, has issued a Call for Papers seeking the world’s best original work in all areas of microelectronics research and development.

The paper submission deadline this year is Wednesday, August 10, 2016. This deadline –– about 1½ months later than has been the norm for the IEDM – reduces the time between paper submissions and publication of the cutting-edge research results for which the conference is known. Also new for 2016 is that authors are asked to submit four-page camera-ready abstracts (instead of three pages), which will be published as-is in the proceedings.

Because of the more abbreviated schedule, only a very limited number of late-news papers will be accepted. Authors are asked to submit late-news abstracts announcing only the most recent and noteworthy developments. The late-news submission deadline is September 12, 2016.

“Because microelectronics technology changes so rapidly, it makes sense to shorten the time between when results are achieved and when they are discussed among the industry’s best and brightest who attend IEDM,” said Dr. Martin Giles, IEDM 2016 Publicity Chair and Intel Fellow and Director of Transistor Technology Variation in Intel’s Technology and Manufacturing Group. “This later submission deadline ensures that the freshest and most up-to-date work can be presented at the conference.”

Overall, the 2016 IEDM is seeking increased participation in the areas of power, wearable/Internet of Things (IoT), ultra-high speed, and quantum computing devices, which will be explored in depth in Special Focus Sessions in each area.

At IEDM each year, the world’s best scientists and engineers in the field of microelectronics from industry, academia and government gather to participate in a technical program of more than 220 presentations, along with special luncheon presentations and a variety of panels, special sessions, Short Courses, IEEE/EDS award presentations and other events spotlighting more leading work in more areas of the field than any other conference.

Papers in the following areas are encouraged:

  • Circuit and Device Interaction
  • Characterization, Reliability and Yield
  • Compound Semiconductor and High-Speed Devices
  • Memory Technology
  • Modeling and Simulation
  • Nano Device Technology
  • Optoelectronics, Displays and Imagers
  • Power Devices
  • Process and Manufacturing Technology
  • Sensors, MEMS and BioMEMS

Further information

For more information, interested persons should visit the IEDM 2016 home page at www.ieee-iedm.org.

LED Taiwan, the most influential LED exhibition in Taiwan, is organized by SEMI and the Taiwan External Trade Development Council (TAITRA). Opening at TWTC Nangang Exhibition Hall in Taipei on April 13-16, the four-day event features theme pavilions, industry forums, TechSTAGE and academic paper presentations. The Taiwan International Lighting Show (TiLS) is co-located. With 748 booths and 238 exhibitors demonstrating the local LED supply chains’ R&D capabilities, LED Taiwan is expected to attract over 16,000 visitors from Taiwan and internationally.

Research firm Strategies Unlimited estimates that the global LED packaging market had US$15.6 billion revenue in 2014. The market is expected to grow to US$22 billion by 2019, 45 percent from lighting applications. However, as the price of white LEDs continues to fall, new applications are regarded as the key to higher earnings. Prospects of niche-market applications like IR LED and UV LED look good, while automotive LED lights are becoming another important market with greater demand for high-power chips.

Five theme pavilions to fully demonstrate a complete LED industry chain

To satisfy the market’s demand for LED in an era of IoT, LED Taiwan 2016 will add three new pavilions — LED Components, Smart Lighting Technology, and Power Device — to the two existing pavilions High-Brightness LED and Sapphire. Leading players in the areas of LED equipment, materials, components and packaging ─ like Aurora Optoelectronics, Cree, Epileds, GlobalWafers, Han’s Laser, Lextar, an alliance of sapphire processing companies organized by the Metal Industries Research & Development Centre, Rapitech, Rubicon and Wei Min Industrial ─ will all showcase their products in the exhibition to help local and foreign visitors understand the structure, manufacturing processes and technologies of Taiwan’s LED industry.

Event to feature the results of innovation in five areas

To enable innovation and bring more energy to the local LED industry, TechSTAGE will be held as part of this year’s LED Taiwan event, showcasing Taiwan’s LED R&D capability in the areas of LED

Manufacturing Equipment & Materials, Power Device Technology, Sapphire Processing Technology & Application, LED Advanced Technologies, and Smart Lighting & Automobile Lighting.

Seeking more possibilities with innovative materials and power devices

As awareness about energy conservation increases around the world and the market seeks better profits and opportunities, more companies are investing in power device R&D and production. This has prompted LED Taiwan to focus on the hot topic of power devices this year, and in addition to a special pavilion for the segment, the event will also organize a forum for vendors to discuss and understand trends and development concerning this technology.

International forums to explore key issues in the industry

As the LED market is gradually maturing, companies in the industry are aggressively seeking new applications and “blue ocean” strategies. In addition to visible LED applications in back-lit display, mobile phones, lighting equipment and cars, more companies have invested in the development and production of invisible LEDs. While demand continues to diversify with a focus on custom-made applications, the ability to find new opportunities in this trend, improving competitiveness and innovation, will be the key to future success. The LED Taiwan 2016 Executive Summit will discuss future trends by exploring innovation, LED lighting/non-lighting opportunities, current challenges and strategies in the market. The IR and UV Summit will focus on IR and UV LED applications in wearable devices, medical appliances and measuring equipment in a bid to help participants get a quick grasp of latest trends around the world.

Integration of resources helps boost local LED industry’s global presence

LED Taiwan is made possible with the collaboration and resources from influential organizations in the industry, including SEMI, TAITRA, the Taiwan Lighting Fixture Export Association and the Taiwan Optoelectronic Semiconductor Industry Association. Each year, foreign buyers and leading manufacturers are invited to the exposition where various business matching events, VIP luncheons and banquet meetings are arranged to help Taiwan vendors expand connections and secure business opportunities by interacting with the elite members of foreign industrial and academic circles.

“SEMI has many connections and resources in the area of LED manufacturing, and by working with the Taiwan Lighting Fixture Export Association and TAITRA, we are able to organize LED Taiwan and TiLS at the same time, ” said Terry Tsao, president of SEMI Taiwan. “In addition to showing the world the robust ecosystem of Taiwan’s LED industry and attracting more foreign buyers, we also hope that innovative technologies and academic papers announced in the forums will help integrate industrial and academic resources. We want to create more opportunities for the LED industry and make Taiwan’s outstanding R&D capabilities visible to the world.”

LED Taiwan is the most influential LED exposition in Taiwan, showcasing LED production equipment & materials, epi wafers, crystals, packaging, modules, etc., as well as related technologies and manufacturing solutions. The Taiwan International Lighting Show is co-located at LED Taiwan as a multi-purpose event facilitating technology exchanges and procurement in the areas of LED and lighting. LED Taiwan was inaugurated in 2010, and in 2015, the event attracted buyers from over 68 countries and created more than US$13 million of business.

For more information on LED Taiwan, please visit: www.ledtaiwan.org/en/

The Internet of Things (IoT) is a technology concept that is currently transforming and redefining virtually all markets and industries in fundamental ways. In fact, IHS forecasts that the IoT market will grow from an installed base of 15.4 billion devices in 2015 to 30.7 billion devices in 2020 and 75.4 billion in 2025, according to “IoT Platforms: Enabling the Internet of Things” a new white paper available as a free download from IHS Inc. (NYSE: IHS), a global source of critical information and insight.

An important sign of the fundamental significance of the IoT concept is that most major information and communication technology vendors are now strategically developing IoT offerings. Companies that sit at the heart of the telecom, networking, industrial infrastructure, enterprise system, and cloud computing sectors are now offering platforms to facilitate the broader economy’s transformation to pervasive connectivity. Over the past five years, fragmented efforts to connect machines and sensors in industry-specific ways are now coalescing into a comprehensive vision of connectivity permeating the global physical environment.

“IoT platforms serve to remove the complexity when developing, deploying, and managing applications over the application lifecycle,” said Sam Lucero, senior principal analyst, IHS Technology. “Moreover, these underlying platforms provide operators flexibility to choose various strategic approaches to the IoT beyond simple managed connectivity offers. IoT platforms enable new value-added services for developers and implementers, while providing complete, end-to-end IoT solutions directly to the market.”

ClassOne Technology, manufacturer of cost-efficient Solstice electroplating systems, has announced the completion of a major new round of funding from Salem Investment Partners of Winston-Salem, North Carolina. The announcement was made jointly by Byron Exarcos, CEO of ClassOne and Meredith Jolly, Vice President at Salem Investment Partners.

“It’s evident that 2016 will be another significant growth year for ClassOne Technology,” said Mr. Exarcos. “With this new funding we will fill order backlogs and address a forecast that is strong and rapidly increasing. This surge in business is coming from the many emerging markets that build products on 200mm and smaller substrates. These users are looking for advanced plating performance at an affordable price — and that’s precisely what Solstice systems are designed for. As a result, more and more of these companies are ordering our tools. And that now includes many of the top-tier manufacturers from around the world.”

“We’re delighted to see the exceptional and sustained growth that ClassOne Technology is achieving across the U.S., Europe and Asia,” said Ms. Jolly. “It’s even more remarkable given that the company just introduced the Solstice system two years ago. It’s great to be on a winning team and to be able to contribute to their success.”

ClassOne’s Solstice electroplating line serves many cost-sensitive emerging markets such as MEMS, Sensors, LEDs, Opto-electronics, RF and more. Designed specifically for ≤200mm wafer processing, Solstice tools are available in three different models and can electroplate a range of metals and alloys, either on transparent or opaque substrates. The company also just announced their Plating-Plus capability which allows Solstice to perform additional processing — such as Metal Lift-Off, Resist Strip and UBM Etch — along with plating, all on a single tool.

In addition to plating equipment, ClassOne also provides spin rinse dryers, spray solvent tools, advanced software and more. ClassOne equipment is strategically priced at less than half of what similar tools from the larger manufacturers would cost — which is why it has been described as “Advanced Wet Processing Tools for the Rest of Us.”

Instead of reading a label, consumers could be interacting with an electronic screen on packaging in the future, thanks to a revolutionary new development by scientists at the University of Sheffield.

The scientists collaborated with technology company Novalia to create a new way of displaying information on packaging, a move that could revolutionise the packaging industry.

This technology could be used in greetings cards or products where a customer could receive a simple message. More complex developments could include a countdown timer on the side of a packet to indicate when a timed product was ready – such as hair-dye, pregnancy tests or home-baking using a ‘traffic lights’ system.

In a paper published in the IEEE Journal of Display Technology, the team explain how a screen can be fixed onto packaging to display information.

The process involves printing electronic tracks onto paper and then fixing low-cost electronics and a polymer LED display to the paper using an adhesive that conducts electricity.

Working together, University of Sheffield scientists and Novalia also designed and constructed a touch-pad keyboard on the paper that allows a user to selectively ‘drive’ the LEDs in the display.

The research has been funded by the Engineering and Physical Sciences Research Council (EPSRC) and testing so far has taken place on paper but the process could potentially be printed on other surfaces.

The team’s next steps are to create fully flexible organic displays on a plastic substrate that then fix onto the electronic tracks. The LED devices need to be low-cost and flexible enough to be used on all packaging.

Professor David Lidzey from the University’s Department of Physics and Astronomy said: “Labels on packaging could become much more innovative, and allow customers to interact with and explore new products. The use of displays or light emitting panels on packaging will also allow companies to communicate brand awareness in a more sophisticated manner.”

Chris Jones from Novalia said: “The paper-based packaging industry is worth billions of dollars. This innovative system we have developed with the University of Sheffield could give manufacturers a way to gain market share by being able to distinguish its products from competitors.”

Harnessing the power of the sun and creating light-harvesting or light-sensing devices requires a material that both absorbs light efficiently and converts the energy to highly mobile electrical current. Finding the ideal mix of properties in a single material is a challenge, so scientists have been experimenting with ways to combine different materials to create “hybrids” with enhanced features.

In two just-published papers, scientists from the U.S. Department of Energy’s Brookhaven National Laboratory, Stony Brook University, and the University of Nebraska describe one such approach that combines the excellent light-harvesting properties of quantum dots with the tunable electrical conductivity of a layered tin disulfide semiconductor. The hybrid material exhibited enhanced light-harvesting properties through the absorption of light by the quantum dots and their energy transfer to tin disulfide, both in laboratory tests and when incorporated into electronic devices. The research paves the way for using these materials in optoelectronic applications such as energy-harvesting photovoltaics, light sensors, and light emitting diodes (LEDs).

According to Mircea Cotlet, the physical chemist who led this work at Brookhaven Lab’s Center for Functional Nanomaterials (CFN), a DOE Office of Science User Facility, “Two-dimensional metal dichalcogenides like tin disulfide have some promising properties for solar energy conversion and photodetector applications, including a high surface-to-volume aspect ratio. But no semiconducting material has it all. These materials are very thin and they are poor light absorbers. So we were trying to mix them with other nanomaterials like light-absorbing quantum dots to improve their performance through energy transfer.”

One paper, just published in the journal ACS Nano, describes a fundamental study of the hybrid quantum dot/tin disulfide material by itself. The work analyzes how light excites the quantum dots (made of a cadmium selenide core surrounded by a zinc sulfide shell), which then transfer the absorbed energy to layers of nearby tin disulfide.

“We have come up with an interesting approach to discriminate energy transfer from charge transfer, two common types of interactions promoted by light in such hybrids,” said Prahlad Routh, a graduate student from Stony Brook University working with Cotlet and co-first author of the ACS Nano paper. “We do this using single nanocrystal spectroscopy to look at how individual quantum dots blink when interacting with sheet-like tin disulfide. This straightforward method can assess whether components in such semiconducting hybrids interact either by energy or by charge transfer.”

The researchers found that the rate for non-radiative energy transfer from individual quantum dots to tin disulfide increases with an increasing number of tin disulfide layers. But performance in laboratory tests isn’t enough to prove the merits of potential new materials. So the scientists incorporated the hybrid material into an electronic device, a photo-field-effect-transistor, a type of photon detector commonly used for light sensing applications.

As described in a paper published online March 24 in Applied Physics Letters, the hybrid material dramatically enhanced the performance of the photo-field-effect transistors-resulting in a photocurrent response (conversion of light to electric current) that was 500 percent better than transistors made with the tin disulfide material alone.

“This kind of energy transfer is a key process that enables photosynthesis in nature,” said Chang-Yong Nam, a materials scientist at Center for Functional Nanomaterials and co-corresponding author of the APL paper. “Researchers have been trying to emulate this principle in light-harvesting electrical devices, but it has been difficult particularly for new material systems such as the tin disulfide we studied. Our device demonstrates the performance benefits realized by using both energy transfer processes and new low-dimensional materials.”

Cotlet concludes, “The idea of ‘doping’ two-dimensional layered materials with quantum dots to enhance their light absorbing properties shows promise for designing better solar cells and photodetectors.”

Researchers from the University of Illinois at Urbana-Champaign have demonstrated a new approach to modifying the light absorption and stretchability of atomically thin two-dimensional (2D) materials by surface topographic engineering using only mechanical strain. The highly flexible system has future potential for wearable technology and integrated biomedical optical sensing technology when combined with flexible light-emitting diodes.

“Increasing graphene’s low light absorption in visible range is an important prerequisite for its broad potential applications in photonics and sensing,” explained SungWoo Nam, an assistant professor of mechanical science and engineering at Illinois. “This is the very first stretchable photodetector based exclusively on graphene with strain-tunable photoresponsivity and wavelength selectivity.”

Graphene–an atomically thin layer of hexagonally bonded carbon atoms–has been extensively investigated in advanced photodetectors for its broadband absorption, high carrier mobility, and mechanical flexibility. Due to graphene’s low optical absorptivity, graphene photodetector research so far has focused on hybrid systems to increase photoabsorption. However, such hybrid systems require a complicated integration process, and lead to reduced carrier mobility due to the heterogeneous interfaces.

According to Nam, the key element enabling increased absorption and stretchability requires engineering the two-dimensional material into three-dimensional (3D) “crumpled structures,” increasing the graphene’s areal density. The continuously undulating 3D surface induces an areal density increase to yield higher optical absorption per unit area, thereby improving photoresponsivity. Crumple density, height, and pitch are modulated by applied strain and the crumpling is fully reversible during cyclical stretching and release, introducing a new capability of strain-tunable photoabsorption enhancement and allowing for a highly responsive photodetector based on a single graphene layer.

“We achieved more than an order-of-magnitude enhancement of the optical extinction via the buckled 3D structure, which led to an approximately 400% enhancement in photoresponsivity,” stated Pilgyu Kang, and first author of the paper, “Crumpled Graphene Photodetector with Enhanced, Strain-tunable and Wavelength-selective Photoresponsivity,” appearing in the journal, Advanced Materials. “The new strain-tunable photoresponsivity resulted in a 100% modulation in photoresponsivity with a 200% applied strain. By integrating colloidal photonic crystal–a strain-tunable optomechanical filter–with the stretchable graphene photodetector, we also demonstrated a unique strain-tunable wavelength selectivity.”

“This work demonstrates a robust approach for stretchable and flexible graphene photodetector devices,” Nam added. “We are the first to report a stretchable photodetector with stretching capability to 200% of its original length and no limit on detection wavelength. Furthermore, our approach to enhancing photoabsorption by crumpled structures can be applied not only to graphene, but also to other emerging 2D materials.”