Home-grown Semiconductors Ideal for Quantum Computing

Growing electronic components directly onto a semiconductor block avoids messy, noisy oxidation scattering that slows and impedes electronic operation. A UNSW (Australia) study out this month shows that the resulting high-mobility components are ideal candidates for high-frequency, ultra-small electronic devices, quantum dots, and for qubit applications in quantum computing.

Making computers faster requires ever-smaller transistors, with these electronic components now only a handful of nanometres in size. (There are around 12 billion transistors in the postage-stamp sized central chip of modern smartphones.)

However, in even smaller devices, the channel that the electrons flow through has to be very close to the interface between the semiconductor and the metallic gate used to turn the transistor on and off.  Unavoidable surface oxidation and other surface contaminants cause unwanted scattering of electrons flowing through the channel, and also lead to instabilities and noise that are particularly problematic for quantum devices.

In the new work we create transistors in which an ultra-thin metal gate is grown as part of the semiconductor crystal, preventing problems associated with oxidation of the semiconductor surface,” says lead author Yonatan Ashlea Alava.

We have demonstrated that this new design dramatically reduces unwanted effects from surface imperfections, and show that nanoscale quantum point contacts exhibit significantly lower noise than devices fabricated using conventional approaches,” says Yonatan, who is a FLEET PhD student.

This new all single-crystal design will be ideal for making ultra-small electronic devices, quantum dots, and for qubit applications,” comments group leader Prof Alex Hamilton at UNSW.

Collaborating with wafer growers at Cambridge University, the team at UNSW Sydney showed that the problem associated with surface charge can be eliminated by growing an epitaxial aluminium gate before removing the wafer from the growth chamber.

We confirmed the performance improvement via characterisation measurements in the lab at UNSW,” says co-author Dr Daisy Wang.

The high conductivity in ultra-shallow wafers, and the compatibility of the structure with reproducible nano-device fabrication, suggests that MBE-grown aluminium gated wafers are ideal candidates for making ultra-small electronic devices, quantum dots, and for qubit applications.

Source: https://www.fleet.org.au/

Commercial Nuclear Fusion Is Closer Than Ever

Nuclear fusion has been seen as the unattainable holy grail of clean energy for decades, but just in the last year it’s been seeming more and more within reach. As catastrophic climate change looms just over the horizon, the scientific community has galvanized to find more and better solutions to decarbonizing the global economy and replacing fossil fuels with a commercially viable, renewable, and green alternative. While much of the time and capital investment has flowed to more realistic options like solar and wind, some researchers have been dedicating their time and energy to capturing the energy of the sun here on earth–a silver bullet solution to global warming.

Conventional nuclear energy has also been hailed as a good, greenhouse gas emissions-free alternative to fossil fuels, but it has some major drawbacks, from the rare but catastrophic instance of nuclear meltdown to the industrial byproduct of nuclear waste. Nuclear fission, which is what nuclear energy plants currently use to create massive amounts of energy by splitting atoms, creates radioactive waste that remains hazardous for tens of thousands of years, if not longer.

The beauty of nuclear fusion is that, not only does it produce energy without creating radioactive waste since it can be achieved using only hydrogen or lithium, it’s also several times more powerful than fission. If we were ever able to harness it in a commercially viable way, it would mean the end of the oil-based economy as we know it. That’s why any news about nuclear fusion is major news. And in the past couple of years, there’s been a lot of new reports emerging about commercial nuclear fusion getting closer and closer to becoming a reality.

Last summer, reps from the International Thermonuclear Experimental Reactor (ITER), an intergovernmental project headquartered in the south of France, reported that they are a mere six and a half years away from achieving first plasma inside their tokamak–in other words: nuclear fusion by just 2025. Then, just a month later in August, 2019, Oak Ridge National Laboratory reported their own nuclear fusion breakthrough, which uses novel implementation of AI and supercomputing to successfully scale up nuclear fusion experiments and manage plasma.

Then, in October, the Los Alamos National Laboratory‘s Plasma Liner Experiment (PLX) unveiled a totally new approach to nuclear fusion, using the very science-fiction combination of plasma guns, magnets, and lasers. According to the American Physical Society, “the PLX machine combines aspects of both magnetic confinement fusion schemes (e.g. tokamaks) and inertial confinement machines like the National Ignition Facility (NIF). The hybrid approach, although less technologically mature than pure magnetic or inertial confinement concepts, may offer a cheaper and less complex fusion reactor development path.” That project is projected to be up and running by the end of this year.

And now, just this week, there are new and exciting claims about yet another novel fusion technology to vie for the best path toward commercial nuclear fusion. Startup HB11, which has its impetus at Australia’s University of New South Wales (UNSW), has pioneered a technology that uses lasers to encourage nuclear fusion between hydrogen and boron without the use of radioactive materials to facilitate the reaction. They’re so confident about the technology that they have already applied for and received patents in the United States, Japan, and China.

The secret,” reports Popular Mechanics, “is a cutting-edge laser and, well, an element of luck.” According to managing director Warren McKenzie, as quoted by New Atlas,You could say we’re using the hydrogen as a dart, and hoping to hit a boron, and if we hit one, we can start a fusion reaction.” While this may sound a little wishy-washy, McKenzie says that the approach is actually more precise than using extreme heat to facilitate fusion because the laser is directed, whereas heat-based reactors waste huge amounts of energy heating up the entire reactor and waiting for a collision to take place.

This means that this new technology–which is now four decades in the making–could make machines like the tokamak obsolete. UNSW emeritus professor Heinrich Hora’s design “seeks to not just compete with but replace entirely the extremely high-temperature current technologies to achieve fusion. These include fussy and volatile designs like the tokamak or stellarator, which can take months to get up to functionality and still spin out of working order in a matter of microseconds.”

Last but not least, two months ago, Newsweek reported that China is about to start operation on its “artificial sun“—a nuclear fusion device that produces energy by replicating the reactions that take place at the center of the sun. If successful, the device could edge scientists closer to achieving the ultimate goal of nuclear fusion: near limitless, cheap clean energy.

Source: https://www.newsweek.com/

Nano Flexible Touchscreens Printed Like Newspaper

Researchers have developed an ultra-thin and ultra-flexible electronic material that could be printed and rolled out like newspaper, for the touchscreens of the future. The touch-responsive technology is 100 times thinner than existing touchscreen materials and so pliable it can be rolled up like a tube.

To create the new conductive sheet, an RMIT University-led team used a thin film common in mobile phone touchscreens and shrunk it from 3D to 2D, using liquid metal chemistry. The nano-thin sheets are readily compatible with existing electronic technologies and because of their incredible flexibility, could potentially be manufactured through roll-to-roll (R2R) processing just like a newspaper. Lead researcher Dr Torben Daeneke said most mobile phone touchscreens were made of a transparent material, indium-tin oxide, that was very conductive but also very brittle.

We’ve taken an old material and transformed it from the inside to create a new version that’s supremely thin and flexible,” said Daeneke, an Australian Research Council DECRA Fellow at RMIT. “You can bend it, you can twist it, and you could make it far more cheaply and efficiently than the slow and expensive way that we currently manufacture touchscreens. “Turning it two-dimensional also makes it more transparent, so it lets through more light. “This means a mobile phone with a touchscreen made of our material would use less power, extending the battery life by roughly 10%.

The research, with collaborators from UNSW, Monash University and the ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), is published in the journal Nature Electronics.

Source: https://www.rmit.edu.au/

How To Make Toxic Water Safe And Drinkable

In Australia, UNSW and RMIT researchers have discovered a revolutionary and cheap way to make filters that can turn water contaminated with heavy metals into safe drinking water in a matter of minutes. Recent UNSW SHARP hire Professor Kourosh Kalantar-zadeh and his former colleagues at RMIT showed that nano-filters made of aluminium oxide could be cheaply produced using virtually no energy from a fixed amount of liquid metal gallium.

In a paper published in Advanced Functional Materials, lead author Dr Ali Zavabeti (RMIT) and Professor Kalantar-zadeh explained that when a chunk of aluminium is added to the core of liquid gallium at room temperature, layers of aluminium oxide are quickly produced at the surface of the gallium. The authors discovered that these aluminium oxide nano-sheets were highly porous and went on to prove they were suitable for filtering both heavy metal ions and oil contamination at unprecedented, ultra-fast rates. Professor Kalantar-zadeh, who was recently awarded an ARC Australian Laureate Fellowship soon after joining UNSW‘s School of Chemical Engineering, said that low cost and portable filters produced by this new liquid metal based manufacturing process could be used by people without access to clean drinking water to remove substances like lead and other toxic metals in a matter of minutes.

Because it’s super porous, water passes through very rapidly,” Professor Kalantar-zadeh said. “Lead and other heavy metals have a very high affinity to aluminium oxide. As the water passes through billions of layers, each one of these lead ions get attracted to one of these aluminium oxide sheets. “But at the same time, it’s very safe because with repeated use, the water flow cannot detach the heavy metal ions from the aluminium oxide.”

Professor Kalantar-zadeh believes the technology could be put to good use in Africa and Asia in places where heavy metal ions in the water are at levels well beyond safe human consumption. It is estimated that 790 million people, or one in 10 of the Earth’s population, do not have access to clean water. “If you’ve got bad quality water, you just take a gadget with one of these filters with you,” he said. “You pour the contaminated water in the top of a flask with the aluminium oxide filter. Wait two minutes and the water that passes through the filter is now very clean water, completely drinkable. “And the good thing is, this filter is cheap.”

There are portable filtration products available that do remove heavy metals from water, but they are comparatively expensive, often costing more than $100. By contrast, aluminium oxide filters produced from liquid gallium could be produced for as little as 10 cents, making them attractive to prospective manufacturers.

Source: http://newsroom.unsw.edu.au/