Category Archives: Materials

After a quiet period due to the saturation of the mobile handset industry, the GaAs wafer market wakes up.  The technical choice made by Apple creates a real and vast enthusiasm for GaAs solutions. 3D sensing in mobile phone as well as LiDAR’s applications are giving a new breath for GaAs substrates suppliers.

Under its new technology & market report “GaAs Wafer & Epiwafer Market: RF, Photonics, LED and PV applications”, Yole Développement (Yole) announces a 15% CAGR between 2017 and 2023 (in volume), with an impressive 37%, especially for photonics applications (1).

GaAs analysis from Yole proposes a comprehensive overview of the GaAs wafer and epi wafer industry. This report outlines Yole’s understanding of the industrial landscape, its evolution as well as the technical challenges. The analysts are offering a relevant technical description of GaAs wafer and epiwafer growth. Market size and forecasts are also delivered in four big applicative markets: RF, Photonics, LED, and PV. Photonics applications are driving the GaAs wafer and epiwafer market into a new era. Yole’s analysts invite you to discover the latest GaAs technology and market trends.

Figure 1

 As one of the most mature compound semiconductors, GaAs has been ubiquitous as the building block of power amplifiers in every mobile handset. In 2018, GaAs RF business represents more than 50% of the GaAs wafer market. However, market growth has slowed down in the past couple years due to the handset market’s gradual saturation and shrinking die size. “At Yole, we expect GaAs to remain the mainstream technology for sub-6 GHz instead of CMOS, owing to GaAs’ high power and linearity performance as required by carrier aggregation and MIMO technology,” explains Dr. Hong Ling, Technology and Market Analyst at Yole.

Since 2017, GaAs wafer has been particularly notable in photonics applications. When Apple introduced its new iPhone X with a 3D sensing function using GaAs-based lasers, it paved the way for a significant boost in the GaAs photonics market. GaAs wafers market segment for photonics applications should reach US$150 million by 2023.

“GaAs-based ROY and infrared LED applications have also caught our attention”, asserts Dr. Ezgi Dogmus, Technology & Market Analyst at Yole. “We estimate, 2017-2023 CAGR achieves 21% (in units) for the total GaAs LED market, surpassing more than half of GaAs wafer volume by 2023.”

In terms of the wafer and epiwafer businesses, each application requires a different size and quality when determining wafer and epiwafer prices. As a new entrant, photonics applications will impose new specification requirements compared to the well-established RF and LED wafer and epiwafers, creating significant ASP diversity.

From a value chain point of view, the GaAs photonics market’s remarkable growth potential will offer plenty of opportunities for wafer, epiwafer, and MOCVD equipment suppliers, as well as for investors.
GaAs wafer supply: Sumitomo Electric, Freiberger Compound Materials, and AXT, involved in GaAs wafer supply, lead the market with about 95% of market share collectively. And since new laser applications have very high specification requirements for GaAs wafer that are constantly evolving, Yole analysts’ expect the top players to maintain their technical advantage for at least another 3 – 5 years.

Regarding GaAs epiwafer production, Yole’s analysts identified different business models. The GaAs LED market is principally vertically integrated, with very well-established IDMs like Osram, San’an, Epistar, and Changelight. In parallel, GaAs RF businesses outsource significantly from well-established epihouses.

Within the GaAs photonics market, the epi business is still applications-dependent. GaAs datacom market segment is mostly epi-integrated, with dominant IDMs like Finisar, Avago, and II-VI. For 3D sensing in smartphones, epi outsourcing is significant.

In 2017, Apple’s supplier Lumentum used IQE as its VCSEL epi supplier. This resulted in an almost 10x increase in IQE’s stock price. Other leading GaAs epihouses are in qualification or ramping up. Yole expects the photonic epiwafer market to behave similar to the GaAs RF epiwafer market.

Using advanced fabrication techniques, engineers at the University of California San Diego have built a nanosized device out of silver crystals that can generate light by efficiently “tunneling” electrons through a tiny barrier. The work brings plasmonics research a step closer to realizing ultra-compact light sources for high-speed, optical data processing and other on-chip applications.

The work is published July 23 in Nature Photonics.

The device emits light by a quantum mechanical phenomenon known as inelastic electron tunneling. In this process, electrons move through a solid barrier that they cannot classically cross. And while crossing, the electrons lose some of their energy, creating either photons or phonons in the process.

Left: schematics of the tunnel junction formed by two edge-to-edge silver single crystal cuboids with an insulating barrier of polyvinylpyrrolidone (PVP). The top inset shows that photons are generated through inelastic electron tunneling. The device performance can be engineered by tuning the size of the cuboids (a, b, c), the gap size (d), and the curvature of silver cuboid edges. Right: TEM image of the tunnel junction, where the gap is around 1.5 nm. Credit: Haoliang Qian/Nature Photonics

Plasmonics researchers have been interested in using inelastic electron tunneling to create extremely small light sources with large modulation bandwidth. However, because only a tiny fraction of electrons can tunnel inelastically, the efficiency of light emission is typically low–on the order of a few hundredths of a percent, at most.

UC San Diego engineers created a device that bumps that efficiency up to approximately two percent. While this is not yet high enough for practical use, it is the first step to a new type of light source, said Zhaowei Liu, a professor of electrical and computer engineering at the UC San Diego Jacobs School of Engineering.

“We’re exploring a new way to generate light,” said Liu.

Liu’s team designed the new light emitting device using computational methods and numerical simulations. Researchers in the lab of Andrea Tao, a professor of nanoengineering at the UC San Diego Jacobs School of Engineering, then constructed the device using advanced solution-based chemistry techniques.

The device is a tiny bow-tie-shaped plasmonic nanostructure consisting of two cuboid, single crystals of silver joined at one corner. Connecting the corners is a 1.5-nanometer-wide barrier of insulator made of a polymer called polyvinylpyrrolidone (PVP).

This tiny metal-insulator-metal (silver-PVP-silver) junction is where the action occurs. Electrodes connected to the nanocrystals allow voltage to be applied to the device. As electrons tunnel from a corner of a silver nanocrystal through the tiny PVP barrier, they transfer energy to surface plasmon polaritons–electromagnetic waves that travel along the metal-insulator interface–which then convert that energy to photons.

But what makes this particular junction more efficient at tunneling electrons inelastically is its geometry and extremely tiny size. By joining two silver single crystals together at their corners with a tiny barrier of insulator in between, researchers essentially created a high quality optical antenna with a high local density of optical states, resulting in more efficient conversion of electronic energy to light.

Metal-insulator-metal junctions have had such low light emission efficiency in the past because they were constructed by joining metal crystals along an entire face, rather than a corner, explained Liu. Giving electrons a high quality optical antenna with a much smaller gap to tunnel through allows efficient light emission, and this kind of structure has been difficult to fabricate with nanolithography methods used in the past, he said.

“Using chemistry, we can build these precise nanosized junctions that allow more efficient light emission,” said Tao. “The fabrication techniques we use give us atomic level control of our materials–we can dictate the size and shape of crystals in solution based on the reagents we use, and we can create structures that have atomically flat faces and extremely sharp corners.”

With additional work, the team aims to further boost efficiency another order of magnitude higher. They are exploring different geometries and materials for future studies.

By Cherry Sun

Storage and memory chipmaker and SEMI China member Tsinghua Unigroup is gearing up to meet burgeoning product demand with huge investments in its manufacturing plants. But the high-tech enterprise under Tsinghua University is eyeing a much bigger prize – growth of the region’s semiconductor industry and the realization of its ambition to become a more prominent force on the global stage.

Inspired by the national strategy, the Tsinghua Unigroup’s big spends include USD 24 billion in Wuhan (Yangtze Memory Technologies Co., Ltd.,) USD 30 billion in Chengdu, USD 30 billion in Nanjing and USD 100 billion in Chongqing, said Liu Hongyu, senior vice president of Tsinghua Unigroup, speaking at the SEMI China Equipment and Materials Committee meeting last month.

Advanced packaging is another rich vein of opportunity the region is tapping for expansion, said Liu Hongjun, vice president of China Wafer Level CSP Co., Ltd., another SEMI China member attending the event, hosted by NAURA in Beijing. Hongjun sees strong growth for Fan-in, Fan-out, FCBGA, 2.5D and 3DIC, with Fan-out out front.

Liang Sheng, administrative commission director at BDA, a business advisory firm supporting high-technology manufacturing in the E-Town economic development zone, pointed to 5G chips and smart, networked electric automobiles as drivers of the next growth phase of Beijing’s integrated circuit (IC) industry.

Global tailwinds are lifting China’s semiconductor industry and the region’s hopes, with SEMI and major industry analysts raising their semiconductor industry growth projects for 2018 to between 9 percent and 16 percent. According to SEMI’s latest market report, global semiconductor industry manufacturing equipment revenue reached USD 17 billion in the first quarter of 2018, logging all-time highs after jumping 12 percent from the previous quarter and 30 percent year-over-year. Korea was the top-performing region at USD 6.26 billion, followed by China at USD 2.64 billion.

Tighter integration with the rest of the global semiconductor industry is critical to the growth of China’s chip sector, and SEMI China is squarely focused on this assimilation, said SEMI China president Lung Chu. The spearhead of this effort is the SEMI Innovation Investment Platform (SIIP) China, established by SEMI China last year to help grow China’s pool of skilled workers, promote advanced technology, generate industry capital, and expand China’s semiconductor industry while developing stronger connections with chip sectors in other regions.

To strengthen ties with other regions, SIIP China will stage a number of innovation and investment forums this year including Chinese Night at SEMICON West (July 10-12) and a SIIP China Forum in Silicon Valley (July 15). In August, representatives from the Korea chip industry will visit counterparts in China (August), and a China delegation will travel to Japan for meetings (October). SIIP China is also strengthening the region’s links with Germany and Israel as SEMI serves as a crucial bridge between China’s semiconductor sector and the global industry.

At the invitation of Shanghai authorities and the Ministry of Commerce of the People’s Republic of China, SEMI China in November will join the China International Export & Import Exposition in Shanghai, an event that will underscore China’s commitment to the openness and cooperation of its semiconductor industry with the international chip community. As part of the exposition, SEMI will work with the Ministry of Commerce and domestic chip manufacturers to begin development of a special integrated circuit (IC) zone. SEMI China members are welcome to participate.

With workforce development no less vital to the future of China’s semiconductor industry, the Equipment & Materials Committee offered potential solutions to the industry’s talent gap. Measures included targeting university students and engineers with industry lectures and courses in key cities, campus recruiting, talent training that members said they are willing to help SEMI coordinate and stage and, much like the push to better integrate China with the global semiconductor industry, mobilizing member resources around a campaign to polish the image of the industry to make it more attractive to students and young workers.

Storage and memory chipmaker and SEMI China member Tsinghua Unigroup is gearing up to meet burgeoning product demand with huge investments in its manufacturing plants.

Cherry Sun is a marketing manager at SEMI China. 

Originally published on the SEMI blog.

Rahul Goyal of Intel has been elected to a one-year term as board chair of Silicon Integration Initiative, a research and development joint venture that provides standard interoperability solutions for integrated circuit design tools. The election was held during Si2’s board meeting at the recent Design Automation Conference.

A member of the Si2 board since 2003, Goyal is vice president, Technology and Manufacturing Group and director, Research and Development Strategic Enabling for Intel. He has global responsibility for strategic sourcing, supply chain strategy, industry relations, ecosystem development, strategic collaborations, data analytics, and capacity management related to product development across Intel’s broad product portfolio. This includes software, system and semiconductor intellectual property, product development outsourcing services, electronic measurement solutions, electronic design automation software, prototyping and verification products used in all aspects of product design, validation and technology development.

Goyal joined Intel in 1989 and has held various technical and management positions in software engineering and technology development. His previous roles there include engineering director in the Design and Technology Solutions Group, director of the integrated silicon technology roadmap development in the Microprocessor Products Group, and senior engineering manager of mask operations.

Goyal holds a bachelor’s degree in electrical and electronics engineering from Birla Institute of Technology and Science, Pilani, India, and a master’s degree in computer engineering from Syracuse University, Syracuse, N.Y.

Taking a multiband approach explains ‘electron-hole reverse drag’ and exciton formation

Mystifying experimental results obtained independently by two research groups in the USA seemed to show coupled holes and electrons moving in the opposite direction to theory.

Now, a new theoretical study has explained the previously mysterious result, by showing that this apparently contradictory phenomenon is associated with the bandgap in dual-layer graphene structures, a bandgap which is very much smaller than in conventional semiconductors.

The study authors, which included FLEET collaborator David Neilson at the University of Camerino and FLEET CI Alex Hamilton at the University of New South Wales, found that the new multiband theory fully explained the previously inexplicable experimental results.

Excitons travel across an ultra-low energy transistor without wasted dissipation of energy. Credit: FLEET: ARC Centre of Excellence in Future Low Energy Electronics Technologies

Exciton transport

Exciton transport offers great promise to researchers, including the potential for ultra-low dissipation future electronics.

An exciton is a composite particle: an electron and a ‘hole’ (a positively charged ‘quasiparticle’ caused by the absence of an electron) bound together by their opposite electrical charges.

In an indirect exciton, free electrons in one 2D sheet can be electrostatically bound to holes that are free to travel in the neighbouring 2D sheet.

Because the electrons and holes are each confined to their own 2D sheets, they cannot recombine, but they can electrically bind together if the two 2D sheets are very close (a few nanometres).

If electrons in the top (‘drive’) sheet are accelerated by an applied voltage, then each partnering hole in the lower (‘drag’) sheet can be ‘dragged’ by its electron.

This ‘drag’ on the hole can be measured as an induced voltage across the drag sheet, and is referred to as Coulomb drag.

A goal in such a mechanism is for the exciton to remain bound, and to travel as a superfluid, a quantum state with zero viscosity, and thus without wasted dissipation of energy.

To achieve this superfluid state, precisely engineered 2D materials must be kept only a few nanometres apart, such that the bound electron and hole are much closer to each other than they are to their neighbours in the same sheet.

In the device studied, a sheet of hexagonal-boron-nitride (hBN) separates two sheets of atomically-thin (2D) bilayer graphene, with the insulating hBN preventing recombination of electrons and holes.

Passing a current through one sheet and measuring the drag signal in the other sheet allows experimenters to measure the interactions between electrons in one sheet and holes in the other, and to ultimately detect a clear signature of superfluid formation.

Only recently, new, 2D heterostructures with sufficiently thin insulating barriers have been developed that allow us to observe features brought by strong electron-hole interactions.

Explaining the inexplicable: negative drag

However, experiments published in 2016 showed extremely puzzling results. Under certain experimental conditions, the Coulomb drag was found to be negative – i.e. moving an electron in one direction caused the hole in the other sheet to move in the opposite direction!

These results could not be explained by existing theories.

In this new study, these puzzling results are explained using crucial multi-band processes that had not previously been considered in theoretical models.

Previous experimental studies of Coulomb drag had been performed in conventional semiconductor systems, which have much larger bandgaps.

However bilayer graphene has a very small bandgap, and it can be changed by the perpendicular electric fields from the metal gates positioned above and below the sample.

The calculation of transport in both conduction and valence bands in each of the graphene bilayers was the ‘missing link’ that marries theory to experimental results. The strange negative drag happens when the thermal energy approaches the bandgap energy.

The strong multiband effects also affect the formation of exciton superfluids in bilayer graphene, so this work opens up new possibilities for exploration in exciton superfluids.

The study Multiband Mechanism for the Sign Reversal of Coulomb Drag Observed in Double Bilayer Graphene Heterostructures by M. Zarenia, A.R. Hamilton, F.M. Peeters and D. Neilson was published in Physical Review Letters in July 2018.

Acknowledgement: The study was led by David Neilson, and by Mohammad Zarenia while at the University of Antwerp, Belgium. The authors of the theoretical study worked with data provided by experimentalists from the two US groups: Cory Dean (Columbia University) and Emanuel Tutuc (University of Texas at Austin) who discovered the original puzzling results. The research was supported by the Flemish government (Belgium), the University of New South Wales, the University of Camerino and by the Australian Research Council via FLEET.

Superfluids and FLEET

Exciton superfluids are studied within FLEET’s Research theme 2 for their potential to carry zero-dissipation electronic current, and thus allow the design of ultra-low energy exciton transistors.

The use of twin atomically-thin (2D) sheets to carry the excitons will allow for room-temperature superfluid flow, which is key if the new technology is to become a viable ‘beyond CMOS’ technology. A bilayer-exciton transistor would be a dissipationless switch for information processing.

In a superfluid, scattering is prohibited by quantum statistics, which means that electrons and holes can flow without resistance.

In this single, pure quantum state, all particles flow with the same momentum, so that no energy can be lost through dissipation.

FLEET (the Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies) brings together over a hundred Australian and international experts, with the shared mission to develop a new generation of ultra-low energy electronics.

The impetus behind such work is the increasing challenge of energy used in computation, which uses 5-8% of global electricity and is doubling every decade.

A key challenge of such ultra-miniature devices is overheating – their ultra-small surfaces seriously limit the ways for the heat from electrical currents to escape.

Working to address “hotspots” in computer chips that degrade their performance, UCLA engineers have developed a new semiconductor material, defect-free boron arsenide, that is more effective at drawing and dissipating waste heat than any other known semiconductor or metal materials.

This could potentially revolutionize thermal management designs for computer processors and other electronics, or for light-based devices like LEDs.

Illustration showing a schematic of a computer chip with a hotspot (bottom); an electron microscope image of defect-free boron arsenide (middle); and an image showing electron diffraction patterns in boron arsenide. Credit: Hu Research Lab / UCLA Samueli

The study was recently published in Science and was led by Yongjie Hu, UCLA assistant professor of mechanical and aerospace engineering.

Computer processors have continued to shrink down to nanometer sizes where today there can be billions of transistors on a single chip. This phenomenon is described under Moore’s Law, which predicts that the number of transistors on a chip will double about every two years. Each smaller generation of chips helps make computers faster, more powerful and able to do more work. But doing more work also means they’re generating more heat.

Managing heat in electronics has increasingly become one of the biggest challenges in optimizing performance. High heat is an issue for two reasons. First, as transistors shrink in size, more heat is generated within the same footprint. This high heat slows down processor speeds, in particular at “hotspots” on chips where heat concentrates and temperatures soar. Second, a lot of energy is used to keep those processors cool. If CPUs did not get as hot in the first place, then they could work faster and much less energy would be needed to keep them cool.

The UCLA study was the culmination of several years of research by Hu and his students that included designing and making the materials, predictive modeling, and precision measurements of temperatures.

The defect-free boron arsenide, which was made for the first time by the UCLA team, has a record-high thermal conductivity, more than three-times faster at conducting heat than currently used materials, such as silicon carbide and copper, so that heat that would otherwise concentrate in hotspots is quickly flushed away.

“This material could help greatly improve performance and reduce energy demand in all kinds of electronics, from small devices to the most advanced computer data center equipment,” Hu said. “It has excellent potential to be integrated into current manufacturing processes because of its semiconductor properties and the demonstrated capability to scale-up this technology. It could replace current state-of-the-art semiconductor materials for computers and revolutionize the electronics industry.”

The study’s other authors are UCLA graduate students in Hu’s research group: Joonsang Kang, Man Li, Huan Wu, and Huuduy Nguyen.

In addition to the impact for electronic and photonics devices, the study also revealed new fundamental insights into the physics of how heat flows through a material.

“This success exemplifies the power of combining experiments and theory in new materials discovery, and I believe this approach will continue to push the scientific frontiers in many areas, including energy, electronics, and photonics applications,” Hu said.

The international team of scientist of Peter the Great St. Petersburg Polytechnic University (SPbPU), Leibniz University Hannover (Leibniz Universität Hannover) and the Ioffe Institute found a way to improve nanocomposite material which opens a new opportunities to use it in hydrogen economy and other industries. The obtained results are explained in the academic article “The mechanism of charge carrier generation at the TiO2–n-Si heterojunction activated by gold nanoparticles” published in journal Semiconductor Science and Technology.

The study is dedicated to the composite material, a semiconductor based on titanium dioxide. Its applications are widely studied by the researchers all over the world. But the processes which take place in this material are very complex. Therefore, to use the semiconductor more effectively, it is necessary to ensure that the energy enclosed between its layers can be released and transmitted.

In framework of the experiments the researchers of SPbPU, Leibniz University Hannover and Ioffe Institute propose a qualitative model to explain the complex processes.

The scientific group used a composite material consisting of a silicon wafer (standard silicon wafer used in electronic devices), gold nanoparticles and a thin layer of titanium dioxide. In the framework of the experiment to transfer the energy inside the material, the researchers intended to isolate nanoparticles from silicon. If nanoparticles are not isolated from the silicon wafer, then the energy can’t be transmitted neither to the silicon nor to the titanium dioxide. It leads to the energy loss.

“The obtained material was a silicon wafer with pillar-like structures grown on its surface. It was used as a substrate for the sample. Gold nanoparticles were situated on top of these pillars and the whole structure was coated with titanium oxide. Thus, nanoparticles contacted only titanium dioxide, and simultaneously were isolated from silicon. The number of boundaries between the layers decreased, we tried to describe the processes in the material. In addition, we assumed that this structure would increase the efficiency of using the energy of light illuminating the surface of our material”, says Dr. Maxim Mishin, professor of Physics, Chemistry, and Technology of Microsystems Equipment Department of SPbPU.

In St. Petersburg, an international scientific group established a model of a new structure, then the main part of the structure was created in Hannover: a silicon wafer with pillars and gold nanoparticles situated on top of it.

The experiment was performed as follows. At first, the wafer was oxidized, i.e. it was covered with a layer of the substrate, and gold nanoparticles were put on top of it.

“After that, we faced the next task: to create pillars and to perform the etching of the substrate so that it is remained under the particles and not and in between them. Considering that we are dealing with nanosizes, the diameter of gold nanoparticles is about 10 nanometers, and the height of the pillar is 80 nanometers, this is not a trivial task. The development of modern nanoelectronics makes it possible to use the so-called “dry” etching methods such as reactive ion etching”, adds Dr. Marc Christopher Wurz from the Institute of Micro Production Technology at Leibniz University Hannover.

According to scientists, the process of technology development had not been rapid: at the first stages of the experiment, while using the ion etching, all gold nanoparticles were simply demolished from the oxidized wafer. In the course of one week, the researchers were selecting the parameters for etching plasma system, so that the gold nanoparticles remained on the surface. The whole experiment was conducted within 10 days.

This scientific project is ongoing. The researchers mention that this nanocomposite material can be used in optical devices operating in the visible light spectrum. In addition, it can be used as a catalyst to produce hydrogen from water, or, for example, to purify water by stimulating the decomposition of complex molecules. In addition, this material may be useful as an element of a sensor which detects a gas leak or increased concentration of harmful substances in the air.

With companies like Google, Microsoft, and IBM all racing to create the world’s first practical quantum computer, scientists worldwide are exploring the potential materials that could be used to build them.

Now, Associate Professor Yang Hyunsoo and his team from the Department of Electrical and Computer Engineering at the National University of Singapore (NUS) Faculty of Engineering have demonstrated a new method which could be used to bring quantum computing closer to reality.

“The NUS team, together with our collaborators from Rutgers, The State University of New Jersey in the United States and RMIT University in Australia, showed a practical way to observe and examine the quantum effects of electrons in topological insulators and heavy metals which could later pave the way for the development of advanced quantum computing components and devices,” explained Assoc Prof Yang.

The findings of the study were published in the scientific journal Nature Communications in June 2018.

The advantage of quantum computers

Quantum computers are still in the early stages of development but are already displaying computing speeds millions of times faster than traditional technologies. As such, it is predicted that when quantum computing becomes more readily available, it will be able to answer some of the world’s toughest questions in everything from finance to physics. This remarkable processing power is made possible by the radical way that quantum computers operate – using light rather than electricity.

Classical computers push electrons through devices which code information into binary states of ones and zeros. In contrast, quantum computers use laser light to interact with electrons in materials to measure the phenomenon of electron “spin”. These spinning electron states replace the ones and zeros used as the basis for traditional computers, and because they can exist in many spin states simultaneously, this allows for much more complex computing to be performed.

However, harnessing information based on the interactions of light and electrons is easier said than done. These interactions are incredibly complex and like anything in the quantum world there is a degree of uncertainty when trying to predict behaviour. As such, a reliable and practical way to observe these quantum effects has been sought-after in recent research to help in the discovery of more advanced quantum computing devices.

Visualising quantum spin effects

The real breakthrough from the scientists at NUS was the ability to “see” for the first time particular spin phenomena in topological insulators and metals using a scanning photovoltage microscope.

Topological insulators are electronic materials that are insulating in their interior but support conducting states on their surface, thus enabling electrons to flow along the surface of the material.

Assoc Prof Yang and his team examined platinum metal as well as topological insulators Bi2Se3 and BiSbTeSe2. An applied electrical current influenced the electron spin at the quantum level for all of these materials and the scientists were able to directly visualise this change using polarised light from the microscope.

Additionally, unlike other observational techniques, the innovative experimental setup meant that the results could be gathered at room temperature, making this a practical method of visualisation which is applicable to many other materials.

Mr Liu Yang, who is a PhD student with the Department and first author of the study, said, “Our method can be used as a powerful and universal tool to detect the spin accumulations in various materials systems. This means that developing better devices for quantum computers will become easier now that these phenomena can be directly observed in this way.”

Next steps

Moving forward, Assoc Prof Yang and his team are planning to test their new method on more novel materials with novel spin properties. The team hopes to work with industry partners to further explore the various applications of this unique technique, with a focus on developing the devices used in future quantum computers.

Silicon Labs (NASDAQ: SLAB), a provider of silicon, software and solutions for a smarter, more connected world, announces two new executive appointments. Daniel Cooley has been named Senior Vice President and Chief Strategy Officer. In this new role, Mr. Cooley will focus on Silicon Labs’ overall growth strategy, business development, new technologies and emerging markets. Matt Johnson, a semiconductor veteran with more than 15 years of industry experience, joins Silicon Labs as Senior Vice President and General Manager of IoT products. Both executives will report to Tyson Tuttle, CEO.

Mr. Cooley has led Silicon Labs’ IoT business for the past four years. Under his leadership, the company built an industry-leading portfolio of secure connectivity solutions, with IoT revenue now exceeding a $100 million per quarter run rate. Mr. Cooley joined Silicon Labs in 2005 as a chip design engineer developing broadcast audio products and short-range wireless devices. Over the years, he has served in various senior management, engineering and product management roles at the company’s Shenzhen, Singapore, Oslo and Austin sites. The new role leverages Mr. Cooley’s proven talents in strategy and business development.

Mr. Johnson will lead Silicon Labs’ IoT business including the development and market success of the company’s broad portfolio of wireless products, microcontrollers, sensors, development tools and wireless software. Mr. Johnson has a track record of growing revenue and leading large global teams, and he brings a deep understanding of analog, MCU and embedded software businesses to Silicon Labs. Previously, he served as Senior Vice President and General Manager of automotive processing products and software development at NXP Semiconductors/Freescale, as well as SVP and General Manager of mobile solutions at Fairchild Semiconductor.

“With these executive appointments, we are expanding our ability to execute on large and growing market opportunities in the IoT,” said Tyson Tuttle, CEO of Silicon Labs. “Together, these two talented leaders will help Silicon Labs scale the business to the next level and focus on future growth.”

Australian scientists have achieved a new milestone in their approach to creating a quantum computer chip in silicon, demonstrating the ability to tune the control frequency of a qubit by engineering its atomic configuration. The work has been published in Science Advances.

A team of researchers from the Centre of Excellence for Quantum Computation and Communication Technology (CQC2T) at UNSW Sydney have successfully implemented an atomic engineering strategy for individually addressing closely spaced spin qubits in silicon.

The frequency spectrum of an engineered molecule. The three peaks represent three different configurations of spins within the atomic nuclei, and the distance between the peaks depends on the exact distance between atoms forming the molecule. Credit: Dr. Sam Hile

The researchers built two qubits – one an engineered molecule consisting of two phosphorus atoms with a single electron, and the other a single phosphorus atom with a single electron – and placed them just 16 nanometres apart in a silicon chip.

By patterning a microwave antenna above the qubits with precision alignment, the qubits were exposed to frequencies of around 40GHz. The results showed that when changing the frequency of the signal used to control the electron spin, the single atom had a dramatically different control frequency compared to the electron spin in the molecule of two phosphorus atoms.

The UNSW researchers collaborated closely with experts at Purdue University, who used powerful computational tools to model the atomic interactions and understand how the position of the atoms impacted the control frequencies of each electron even by shifting the atoms by as little as one nanometre.

“Individually addressing each qubit when they are so close is challenging,” says UNSW Scientia Professor Michelle Simmons, Director CQC2T and co-author of the paper.

“The research confirms the ability to tune neighbouring qubits into resonance without impacting each other.”

Creating engineered phosphorus molecules with different separations between the atoms within the molecule allows for families of qubits with different control frequencies. Each molecule can be operated individually by selecting the frequency that controls its electron spin.

“We can tune into this or that molecule – a bit like tuning in to different radio stations,” says Sam Hile, lead co-author of the paper and Research Fellow at UNSW.

“It creates a built-in address which will provide significant benefits for building a silicon quantum computer.”

Tuning in and individually controlling qubits within a 2 qubit system is a precursor to demonstrating the entangled states that are necessary for a quantum computer to function and carry out complex calculations.

These results show how the team – led by Professor Simmons – have further built on their unique Australian approach of creating quantum bits from precisely positioned individual atoms in silicon.

By engineering the atomic placement of the atoms within the qubits in the silicon chip, the molecules can be created with different resonance frequencies. This means that controlling the spin of one qubit will not affect the spin of the neighbouring qubit, leading to fewer errors – an essential requirement for the development of a full-scale quantum computer.

“The ability to engineer the number of atoms within the qubits provides a way of selectively addressing one qubit from another, resulting in lower error rates even though they are so closely spaced,” says Professor Simmons.

“These results highlight the ongoing advantages of atomic qubits in silicon.”

This latest advance in spin control follows from the team’s recent research into controllable interactions between two qubits.