Category Archives: Process Materials

Researchers at Duke University and North Carolina State University have demonstrated the first custom semiconductor microparticles that can be steered into various configurations repeatedly while suspended in water.

With an initial six custom particles that predictably interact with one another in the presence of alternating current (AC) electric fields of varying frequencies, the study presents the first steps toward realizing advanced applications such as artificial muscles and reconfigurable computer systems.

The study appears online on May 3 in the journal Nature Communications.

“We’ve engineered and encoded multiple dynamic responses in different microparticles to create a reconfigurable silicon toolbox,” said Ugonna Ohiri, a recently graduated electrical engineering doctoral student from Duke and first author of the paper. “By providing a means of controllably assembling and disassembling these particles, we’re bringing a new tool to the field of active matter.”

While previous researchers have worked to define self-assembling systems, few have worked with semiconductor particles, and none have explored the wide range of custom shapes, sizes and coatings that are available to the micro- and nanofabrication industry. Engineering particles from silicon presents the opportunity to physically realize electronic devices that can self-assemble and disassemble on demand. Customizing their shapes and sizes presents opportunities to explore a wide-ranging design space of new motile behaviors.

“Most previous work performed using self-assembling particles has been done with shapes such as spheres and other off-the-shelf materials,” said Nan Jokerst, the J. A. Jones Professor of Electrical and Computer Engineering at Duke. “Now that we can customize whatever arbitrary shapes, electrical characteristics and patterned coatings we want with silicon, a whole new world is opening up.”

In the study, Jokerst and Ohiri fabricated silicon particles of various shapes, sizes and electrical properties. In collaboration with Orlin Velev, the INVISTA Professor of Chemical and Biomolecular Engineering at NC State, they characterized how these particles responded to different magnitudes and frequencies of electric fields while submerged in water.

Based on these observations, the researchers then fabricated new batches of customized particles that were likely to exhibit the behaviors they were looking for, resulting in six different engineered silicon microparticle compositions that could move through water, synchronize their motions, and reversibly assemble and disassemble on demand.

The thin film particles are 10-micron by 20-micron rectangles that are 3.5 microns thick. They’re fabricated using Silicon-on-Insulator (SOI) technology. Since they can be made using the same fabrication technology that produces integrated circuits, millions of identical particles could be produced at a time.

“The idea is that eventually we’re going to be able to make silicon computational systems that assemble, disassemble and then reassemble in a different format,” said Jokerst. “That’s a long way off in the future, but this work provides a sense of the capabilities that are out there and is the first demonstration of how we might achieve those sorts of devices.”

That is, however, only the tip of the proverbial iceberg. Some of the particles were fabricated with both p-type and n-type regions to create p-n junctions — common electrical components that allow electricity to pass in only one direction. Tiny metal patterns were also placed on the particles’ surfaces to create p-n junction diodes with contacts. In the future, researchers could even engineer particles with patterns using other electrically conductive or insulating materials, complex integrated circuits, or microprocessors on or within the silicon.

“This work is just a small snapshot of the tools we have to control particle dynamics,” said Ohiri. “We haven’t even scratched the surface of all of the behaviors that we can engineer, but we hope that this multidisciplinary study can pioneer future studies to design artificial active materials.”

A simple method that uses hydrogen chloride can better control the crystal structure of a common semiconductor and shows promise for novel high-powered electronic applications.

The electronic components used in computers and mobile devices operate at relatively lower power. But high-power applications, such as controlling electrical power grids, require alternative materials that can cope with much higher voltages. For example, an insulating material begins to conduct electricity when the field is high enough, an effect known as electrical breakdown. For this reason, power electronics often use nitride-based semiconductors, such as gallium nitride, which have a very high breakdown field and can be epitaxially grown to create multilayered semiconductors.

However, ever-increasing energy demands and the desire to make electricity distribution more efficient requires even more electrically robust materials. Gallium oxide (Ga2O3) has a theoretical breakdown field more than twice that of gallium-nitride alloys and so has emerged as an exciting candidate for this function. The latest challenge however is a simple way to deposit high-quality gallium oxide on the substrates commonly used for power electronics, such as sapphire.

Haiding Sun, Xiaohang Li, and co-workers from KAUST worked with industry partners Structured Materials Industries, Inc. in the U.S. to demonstrate a relatively simple method to control the crystal structure of gallium oxides on a sapphire substrate using a technology known as metalorganic chemical vapor deposition (MOCVD). “We were able to control the growth by changing just one parameter: the flow rate of hydrogen chloride in the chamber,” explains Sun. “This is the first time that hydrogen chloride has been used during oxide growth in an MOCVD reactor.”

Working in a clean suit in the lab, Dr. Sun holds up a gallium-oxide template. Credit: © 2018 KAUST

Working in a clean suit in the lab, Dr. Sun holds up a gallium-oxide template. Credit: © 2018 KAUST

The atoms in gallium oxide can be arranged in a number of different forms known as polymorphs. β­­­?Ga2O3 is the most stable polymorph but is difficult to grow on substrates of other materials. ε?Ga2O3 has been grown on sapphire but its growth rate has been difficult to control.

Different polymorphs of gallium oxide can be grown in a MOCVD chamber by controlling the flow of hydrogen chloride.

Different polymorphs of gallium oxide can be grown in a MOCVD chamber by controlling the flow of hydrogen chloride.

Engineers at the University of California, Riverside, have demonstrated prototype devices made of an exotic material that can conduct a current density 50 times greater than conventional copper interconnect technology.

Current density is the amount of electrical current per cross-sectional area at a given point. As transistors in integrated circuits become smaller and smaller, they need higher and higher current densities to perform at the desired level. Most conventional electrical conductors, such as copper, tend to break due to overheating or other factors at high current densities, presenting a barrier to creating increasingly small components.

Microscopy image of an electronic device made with 1D ZrTe3 nanoribbons. The nanoribbon channel is indicated in green color. The metal contacts are shown in yellow color. Note than owing to the nanometer scale thickness the yellow metal contacts appear to be under the green channel while in reality they are on top. Credit: Balandin lab, UC Riverside

Microscopy image of an electronic device made with 1D ZrTe3 nanoribbons. The nanoribbon channel is indicated in green color. The metal contacts are shown in yellow color. Note than owing to the nanometer scale thickness the yellow metal contacts appear to be under the green channel while in reality they are on top. Credit: Balandin lab, UC Riverside

The electronics industry needs alternatives to silicon and copper that can sustain extremely high current densities at sizes of just a few nanometers.

The advent of graphene resulted in a massive, worldwide effort directed at investigation of other two-dimensional, or 2D, layered materials that would meet the need for nanoscale electronic components that can sustain a high current density. While 2D materials consist of a single layer of atoms, 1D materials consist of individual chains of atoms weakly bound to one another, but their potential for electronics has not been as widely studied.

One can think of 2D materials as thin slices of bread while 1D materials are like spaghetti. Compared to 1D materials, 2D materials seem huge.

A group of researchers led by Alexander A. Balandin, a distinguished professor of electrical and computer engineering in the Marlan and Rosemary Bourns College of Engineering at UC Riverside, discovered that zirconium tritelluride, or ZrTe3, nanoribbons have an exceptionally high current density that far exceeds that of any conventional metals like copper.

The new strategy undertaken by the UC Riverside team pushes research from two-dimensional to one-dimensional materials­­– an important advance for the future generation of electronics.

“Conventional metals are polycrystalline. They have grain boundaries and surface roughness, which scatter electrons,” Balandin said. “Quasi-one-dimensional materials such as ZrTe3consist of single-crystal atomic chains in one direction. They do not have grain boundaries and often have atomically smooth surfaces after exfoliation. We attributed the exceptionally high current density in ZrTe3 to the single-crystal nature of quasi-1D materials.”

In principle, such quasi-1D materials could be grown directly into nanowires with a cross-section that corresponds to an individual atomic thread, or chain. In the present study the level of the current sustained by the ZrTe3 quantum wires was higher than reported for any metals or other 1D materials. It almost reaches the current density in carbon nanotubes and graphene.

Electronic devices depend on special wiring to carry information between different parts of a circuit or system. As developers miniaturize devices, their internal parts also must become smaller, and the interconnects that carry information between parts must become smallest of all. Depending on how they are configured, the ZrTe3 nanoribbons could be made into either nanometer-scale local interconnects or device channels for components of the tiniest devices.

The UC Riverside group’s experiments were conducted with nanoribbons that had been sliced from a pre-made sheet of material. Industrial applications need to grow nanoribbon directly on the wafer. This manufacturing process is already under development, and Balandin believes 1D nanomaterials hold possibilities for applications in future electronics.

“The most exciting thing about the quasi-1D materials is that they can be truly synthesized into the channels or interconnects with the ultimately small cross-section of one atomic thread– approximately one nanometer by one nanometer,” Balandin said.

In even the most fuel-efficient cars, about 60 percent of the total energy of gasoline is lost through heat in the exhaust pipe and radiator. To combat this, researchers are developing new thermoelectic materials that can convert heat into electricity. These semiconducting materials could recirculate electricity back into the vehicle and improve fuel efficiency by up to 5 percent.

The challenge is, current thermoelectric materials for waste heat recovery are very expensive and time consuming to develop. One of the state of the art materials, made from a combination of hafnium and zirconium (elements most commonly used in nuclear reactors), took 15 years from its initial discovery to optimized performance.

Now, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed an algorithm that can discover and optimize these materials in a matter of months, relying on solving quantum mechanical equations, without any experimental input.

“These thermoelectric systems are very complicated,” said Boris Kozinsky, a recently appointed Associate Professor of Computational Materials Science at SEAS and senior author of the paper. “Semiconducting materials need to have very specific properties to work in this system, including high electrical conductivity, high thermopower, and low thermal conductivity, so that all that heat gets converted into electricity. Our goal was to find a new material that satisfies all the important properties for thermoelectric conversion while at the same time being stable and cheap.”

Kozinsky co-authored the research with Georgy Samsonidze, a research engineer at the Robert Bosch Research and Technology Center in Cambridge, MA, where both authors conducted most of the research.

In order to find such a material, the team developed an algorithm that can predict electronic transport properties of a material based only on the chemical elements used in the crystalline crystal. The key was to simplify the computational approach for electron-phonon scattering and to speed it up by about 10,000 times, compared to existing algorithms.

The new method and computational screening results are published in Advanced Energy Materials.

Using the improved algorithm, the researchers screened many possible crystal structures, including structures that had never been synthesized before. From those, Kozinsky and Samsonidze whittled the list down to several interesting candidates. Of those candidates, the researchers did further computational optimization and sent the top performers to the experimental team.

In an earlier effort experimentalists synthesized the top candidates suggested by these computations and found a material that was as efficient and as stable as previous thermoelectric materials but 10 times cheaper. The total time from initial screening to working devices: 15 months.

“We did in 15 months of computation and experimentation what took 15 years for previous materials to be optimized,” said Kozinsky. “What’s really exciting is that we’re probably not fully understanding the extent of the simplification yet. We could potentially make this method even faster and cheaper.”

Kozinsky said he hopes to improve the new methodology and use it to explore electronic transport in a wider class of new exotic materials such as topological insulators.

Japanese researchers have developed a new method to build large areas of semiconductive material that is just two molecules thick and a total of 4.4 nanometers tall. The films function as thin film transistors, and have potential future applications in flexible electronics or chemical detectors. These thin film transistors are the first example of semiconductive single molecular bilayers created with liquid solution processing, a standard manufacturing process that minimizes costs.

Top surface view of 3-D computer model (left) and Atomic Force Microscopy image (right) of the new film made by University of Tokyo scientists. The well-organized structure of the molecules is visible in both the 3-D computer model and microscope image as a herringbone or cross-hair pattern. The color differences in the microscopy image are a result of the different lengths of the molecules' tails; the length differences cause the geometric frustration that prevents layers from stacking. pm = picometers, nm = nanometers. Credit: Shunto Arai and Tatsuo Hasegawa

Top surface view of 3-D computer model (left) and Atomic Force Microscopy image (right) of the new film made by University of Tokyo scientists. The well-organized structure of the molecules is visible in both the 3-D computer model and microscope image as a herringbone or cross-hair pattern. The color differences in the microscopy image are a result of the different lengths of the molecules’ tails; the length differences cause the geometric frustration that prevents layers from stacking. pm = picometers, nm = nanometers. Credit: Shunto Arai and Tatsuo Hasegawa

“We want to give electronic devices the features of real cell membranes: flexible, strong, sensitive, and super thin. We found a novel way to design semiconductive single molecular bilayers that allows us to manufacture large surface areas, up to 100 square centimeters (39 square inches). They can function as high performance thin film transistors and could have many applications in the future,” said Assistant Professor Shunto Arai, the first author on the recent research publication.

Professor Tatsuo Hasegawa of the University of Tokyo Department of Applied Physics led the team that built the new film. The breakthrough responsible for their success is a concept called geometric frustration, which uses a molecular shape that makes it difficult for molecules to settle in multiple layers on top of each other.

The film is transparent, but the forces of attraction and repulsion between the molecules create an organized, repeated herringbone pattern when the film is viewed from above through a microscope. The overall molecular structure of the bilayer is highly stable. Researchers believe it should be possible to build the same structure out of different molecules with different functionalities.

The individual molecules used in the current film are divided into two regions: a head and a tail. The head of one molecule stacks on top of another, with their tails pointing in opposite directions so the molecules form a vertical line. These two molecules are surrounded by identical head-to-head pairs of molecules, which all together form a sandwich called a molecular bilayer.

Researchers discovered they could prevent additional bilayers from stacking on top by building the bilayer out of molecules with different length tails, so the surfaces of the bilayer are rough and naturally discourage stacking. This effect of different lengths is referred to as geometric frustration.

Standard methods of creating semiconductive molecular bilayers cannot control the thickness without causing cracks or an irregular surface. The geometric frustration of different length tails has allowed researchers to avoid these pitfalls and build a 10cm by 10cm (3.9 inches by 3.9 inches) square of their film using the common industrial method of solution processing.

The semiconductive properties of the bilayer may give the films applications in flexible electronics or chemical detection.

Semiconductors are able to switch between states that allow electricity to flow (conductors) and states that prevent electricity from flowing (insulators). This on-off switching is what allows transistors to quickly change displayed images, such as a picture on an LCD screen. The single molecular bilayer created by the UTokyo team is much faster than amorphous silicon thin film transistors, a common type of semiconductor currently used in electronics.

The team will continue to investigate the properties of geometrically frustrated single molecular bilayers and potential applications for chemical detection. Collaborators based at the National Institute of Advanced Industrial Science and Technology, the Nippon Kayaku Company Limited, Condensed Matter Research Center, and High Energy Accelerator Research Organization also contributed to the research.

Cheap, flexible and sustainable plastic semiconductors will soon be a reality thanks to a breakthrough by chemists at the University of Waterloo.

Professor Derek Schipper and his team at Waterloo have developed a way to make conjugated polymers, plastics that conduct electricity like metals, using a simple dehydration reaction the only byproduct of which is water.

“Nature has been using this reaction for billions of years and industry more than a hundred,” said Schipper, a professor of Chemistry and a Canada Research Chair in Organic Material Synthesis. “It’s one of the cheapest and most environmentally friendly reactions for producing plastics.”

Schipper and his team have successfully applied this reaction to create poly(hetero)arenes, one of the most studied classes of conjugated polymers which have been used to make lightweight, low- cost electronics such as solar cells, LED displays, and chemical and biochemical sensors.

Dehydration is a common method to make polymers, a chain of repeating molecules or monomers that link up like a train. Nature uses the dehydration reaction to make complex sugars from glucose, as well as proteins and other biological building blocks such as cellulose. Plastics manufacturers use it to make everything from nylon to polyester, cheaply and in mind-boggling bulk.

“Synthesis has been a long-standing problem in this field,” said Schipper. “A dehydration method such as ours will streamline the entire process from discovery of new derivatives to commercial product development. Better still, the reaction proceeds relatively fast and at room temperature.”

Conjugated polymers were first discovered by Alan Heeger, Alan McDonald, and Hideki Shirakawa in the late 1970s, eventually earning them the Nobel Prize in Chemistry in 2000.

Researchers and engineers quickly discovered several new polymer classes with plenty of commercial applications, including a semiconducting version of the material; but progress has stalled in reaching markets in large part because conjugated polymers are so hard to make. The multi-step reactions often involve expensive catalysts and produce environmentally harmful waste products.

Schipper and his team are continuing to perfect the technique while also working on developing dehydration synthesis methods for other classes of conjugated polymers. The results of their research so far appeared recently in the journal Chemistry – A European Journal.

 

SEMI, the global industry association representing the electronics manufacturing supply chain, today announced that in 2017 the global semiconductor materials market grew 9.6 percent while worldwide semiconductor revenues increased 21.6 percent from the prior year.

According to the SEMI Materials Market Data Subscription, total wafer fabrication materials and packaging materials totaled $27.8 billion and $19.1* billion, respectively, in 2017. In 2016, the wafer fabrication materials and packaging materials markets logged revenues of $24.7 billion and $18.2 billion, respectively, for 12.7 percent and 5.4 percent year-over-year increases.

For the eighth consecutive year, Taiwan, at $10.3 billion, was the largest consumer of semiconductor materials due to its large foundry and advanced packaging base. China solidified its hold on the second spot, followed by South Korea and Japan. The Taiwan, China, Europe and South Korea markets saw the strongest revenue growth, while the North America, Rest of World (ROW) and Japan materials markets experienced moderate single-digit growth. (The ROW region is defined as Singapore, Malaysia, Philippines, other areas of Southeast Asia and smaller global markets.)

2016 and 2017 Regional Semiconductor Materials Markets (US$ Billions)

Region
2016**
2017
% Change
Taiwan
9.20
10.29
12%
China
6.80
7.62
12%
South Korea
6.77
7.51
11%
Japan
6.76
7.05
4%
Rest of World
5.39
5.81
8%
North America
4.87
5.29
9%
Europe
3.03
3.36
11%
Total
42.82
46.93
10%

Source: SEMI, April 2018

Note: Summed subtotals may not equal the total due to rounding.

* Includes ceramic packages and flexible substrates

** 2016 data have been updated based on SEMI’s data collection programs

The Materials Market Data Subscription (MMDS) from SEMI provides current revenue data along with seven years of historical data and a two-year forecast. The annual subscription includes four quarterly updates for the materials segment reports revenue for seven market regions (North America, Europe, ROW, Japan, Taiwan, South Korea, and China).

In a recent study published in Science, researchers at ICFO – The Institute of Photonic Sciences in Barcelona, Spain, along with other members of the Graphene Flagship, reached the ultimate level of light confinement. They have been able to confine light down to a space one atom, the smallest possible. This will pave the way to ultra-small optical switches, detectors and sensors.

Light can function as an ultra-fast communication channel, for example between different sections of a computer chip, but it can also be used for ultra-sensitive sensors or on-chip nanoscale lasers. There is currently much research into how to further shrink devices that control and guide light.

New techniques searching for ways to confine light into extremely tiny spaces, much smaller than current ones, have been on the rise. Researchers had previously found that metals can compress light below the wavelength-scale (diffraction limit), but more confinement would always come at the cost of more energy loss. This fundamental issue has now been overcome.

“Graphene keeps surprising us: nobody thought that confining light to the one-atom limit would be possible. It will open a completely new set of applications, such as optical communications and sensing at a scale below one nanometer,” said ICREA Professor Frank Koppens at ICFO – The Institute of Photonic Sciences in Barcelona, Spain, who led the research.

This team of researchers including those from ICFO (Spain), University of Minho (Portugal) and MIT (USA) used stacks of two-dimensional materials, called heterostructures, to build up a new nano-optical device. They took a graphene monolayer (which acts as a semi-metal), and stacked onto it a hexagonal boron nitride (hBN) monolayer (an insulator), and on top of this deposited an array of metallic rods. They used graphene because it can guide light in the form of plasmons, which are oscillations of the electrons, interacting strongly with light.

“At first we were looking for a new way to excite graphene plasmons. On the way, we found that the confinement was stronger than before and the additional losses minimal. So we decided to go to the one atom limit with surprising results,” said David Alcaraz Iranzo, the lead author from ICFO.

By sending infra-red light through their devices, the researchers observed how the plasmons propagated in between the metal and the graphene. To reach the smallest space conceivable, they decided to reduce the gap between the metal and graphene as much as possible to see if the confinement of light remained efficient, i.e. without additional energy losses. Strikingly, they saw that even when a monolayer of hBN was used as a spacer, the plasmons were still excited, and could propagate freely while being confined to a channel of just one atom thick. They managed to switch this plasmon propagation on and off, simply by applying an electrical voltage, demonstrating the control of light guided in channels smaller than one nanometer.

This enables new opto-electronic devices that are just one nanometer thick, such as ultra-small optical switches, detectors and sensors. Due to the paradigm shift in optical field confinement, extreme light-matter interactions can now be explored that were not accessible before. The atom-scale toolbox of two-dimensional materials has now also proven applicable for many types of new devices where both light and electrons can be controlled even down to the scale of a nanometer.

Professor Andrea C. Ferrari, Science and Technology Officer of the Graphene Flagship, and Chair of its Management Panel, added “While the flagship is driving the development of novel applications, in particular in the field of photonics and optoelectronics, we do not lose sight of fundamental research. The impressive results reported in this paper are a testimony to the relevance for cutting edge science of the Flagship work. Having reached the ultimate limit of light confinement could lead to new devices with unprecedented small dimensions.”

Versum Materials, Inc. (NYSE: VSM), a materials supplier to the semiconductor industry, announced today the grand opening of its new research and development (R&D) facility at its semiconductor materials manufacturing site in Hometown, Pennsylvania. The ribbon-cutting ceremony took place April 10, 2018. Versum employees, members of the community, local government, customers and strategic partners attended the event.

The R&D laboratory is dedicated to new materials used in the manufacture of semiconductors. Scientists in the facility will synthesize and purify new molecules down to parts per billion impurity levels and below using the latest technologies available in the industry. The researchers can assess the applications for these new molecules and scale up the molecules to larger quantities for customer evaluation. These new organometallic compounds will be deposited on semiconductor wafers through cutting-edge technologies to test their performance for semiconductor applications. Additionally, the facility is capable of small-volume manufacturing and advanced analytical and quality assessment.

State Senator Dave Argall commended Versum for being the region’s third largest employer and for the company’s investments in the local community. Approximately 30 employees, half of which hold advanced degrees in chemistry or chemical engineering, are based in the new facility. The company’s Hometown campus now totals 250 highly-skilled employees.

The latest expansion is part of a $60MM multi-year investment in the Hometown campus. Last year the company announced it had increased production capacity and modified equipment configuration to reduce manufacturing bottlenecking. Versum’s Hometown manufacturing facility produces a variety of high purity specialty gases and chemicals for semiconductor manufacturers around the world, including Tungsten Hexafluoride, WF6 and Nitrogen Trifluoride, NF3. WF6 is used as a metallization source for the formation of tungsten interconnects between multiple layers in semiconductor devices. It is an important material in the production of both logic and memory (DRAM and NAND) devices. NF3 is primarily used for chamber cleaning of chemical vapor deposition reactors.

Versum’s Senior Vice President of Materials, Ed Shober addressed the attendees stating, “We enable the largest tech companies around the world to stretch the boundaries of science and technology, whether it be supporting computing power, mobility, connectivity, artificial intelligence, virtual/augmented reality, the Internet of Things, Big Data and machine learning. Versum Materials is at the core of enabling all these technologies. Our Versum Materials team delivers valued products and solutions that bring this cutting-edge innovation to the market safer, faster, easier and more reliably than ever before.”

A current area of intense interest in nanotechnology is van der Waals heterostructures, which are assemblies of atomically thin two-dimensional (2D) crystalline materials that display attractive conduction properties for use in advanced electronic devices.

A representative 2D semiconductor is graphene, which consists of a honeycomb lattice of carbon atoms that is just one atom thick. The development of van der Waals heterostructures has been restricted by the complicated and time-consuming manual operations required to produce them. That is, the 2D crystals typically obtained by exfoliation of a bulk material need to be manually identified, collected, and then stacked by a researcher to form a van der Waals heterostructure. Such a manual process is clearly unsuitable for industrial production of electronic devices containing van der Waals heterostructures

Now, a Japanese research team led by the Institute of Industrial Science at The University of Tokyo has solved this issue by developing an automated robot that greatly speeds up the collection of 2D crystals and their assembly to form van der Waals heterostructures. The robot consists of an automated high-speed optical microscope that detects crystals, the positions and parameters of which are then recorded in a computer database. Customized software is used to design heterostructures using the information in the database. The heterostructure is then assembled layer by layer by a robotic equipment directed by the designed computer algorithm. The findings were reported in Nature Communications.

Robot developed for automated assembly of designer nanomaterials. Credit: 2018 SATORU MASUBUCHI, INSTITUTE OF INDUSTRIAL SCIENCE, THE UNIVERSITY OF TOKYO

Robot developed for automated assembly of designer nanomaterials. Credit: 2018 SATORU MASUBUCHI, INSTITUTE OF INDUSTRIAL SCIENCE, THE UNIVERSITY OF TOKYO

“The robot can find, collect, and assemble 2D crystals in a glove box,” study first author Satoru Masubuchi says. “It can detect 400 graphene flakes an hour, which is much faster than the rate achieved by manual operations.”

When the robot was used to assemble graphene flakes into van der Waals heterostructures, it could stack up to four layers an hour with just a few minutes of human input required for each layer. The robot was used to produce a van der Waals heterostructure consisting of 29 alternating layers of graphene and hexagonal boron nitride (another common 2D semiconductor). The record layer number of a van der Waals heterostructure produced by manual operations is 13, so the robot has greatly increased our ability to access complex van der Waals heterostructures.

“A wide range of materials can be collected and assembled using our robot,” co-author Tomoki Machida explains. “This system provides the potential to fully explore van der Waals heterostructures.”

The development of this robot will greatly facilitate production of van der Waals heterostructures and their use in electronic devices, taking us a step closer to realizing devices containing atomic-level designer materials.