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Silicon now Crystalized: Pathway to Electronic Advancements

June 8th, 2021
Digital Strategy

Silicon now Crystalized: Pathway to Electronic Advancements

June 8th, 2021
Digital Strategy

A team led by Thomas Schill Carnegie and Timothy Strobel developed a new method for synthesizing a new silicon crystal form with a hexagonal structure that could potentially be used to build next-generation electronic and electrical devices with improved features. The shape of the cube is “normal”. Silicone used today.

The new form of silicon can activate next-generation electronic devices and energy

A new, crystallized form of silicon could potentially be used to produce next-generation electronics and energy.

His work will be published in Physical Review Letters.

Silicon plays a big role in human life. This is the second most abundant element in the Earth’s crust. In combination with other elements, it is essential for many construction and infrastructure projects. And in its purest form, it’s so important to computer science that it was nicknamed after the United States Center for Long-Term Technology – Silicon Valley, California.

Chemical properties of crystalized silicon

Like all elements, silicon can have different crystal shapes called allotropes, just as soft graphite and ultra-hard diamond are both forms of carbon. The silicone form, commonly used in electronic devices such as computers and solar panels, has a diamond-like structure. This form of silicon, despite being ubiquitous, is not fully optimized for next-generation applications, including high-power transistors and some photovoltaic devices.

While many different silicon allotropes with improved physical properties are theoretically possible, there are only a few in practice because no known synthetic pathway is currently available.

Strobe Labs had previously created a revolutionary new form of silicon called Si24, which has an open framework consisting of a set of one-dimensional channels. In this new work, Shiell and Strobel led a team that used Si24 as the starting point for a multi-stage artificial pathway that led to the production of highly directional crystals called silicon 4H, which were replicated in four layers. A hexagonal structure is named.

Tomorrow’s advanced technology requires electronics that can withstand extreme conditions. Because of this, today a team of researchers led by Jason Nicholas of Michigan State University is building stronger circuits.

Nicholas and his team used nickel to make heat-resistant silver circuits. The team described the US Department of Solid Energy Fuel Fuel Program as sponsored by Scripta Materialia since April 15.

The types of devices that the MSU team is working on – next-generation fuel cells, high-temperature semiconductors, and solid oxide electrolyte cells – can be used in the automotive, energy, and aerospace industries.

While these devices can no longer be purchased off the shelf, researchers are currently building them in laboratories to test them in the real world and even on other planets.

How this type of silicone can be used 

For example, NASA created a solid oxide electrolyte cell that enabled the Mars 2020 Perseverance Rover to produce oxygen from gas in the Martian atmosphere on April 22.

NASA hopes the prototype will one day lead to devices that astronauts can use to generate rocket fuel and breathable air while on Mars.

“For these prototypes to become commercial goods, they have to maintain their performance at high temperatures for a long time,” said Nicholas, an associate professor at the College of Engineering.

He was drawn to the area after years of using solid oxide fuel cells, which act like reverse solid oxide electrolyte cells. Instead of using energy to produce gases or fuels, they produce energy from these chemicals.

“Solid oxide fuel cells work with gases at high temperatures. We can electrochemically react these gases to generate electricity, and this process is much more efficient than blasting a fuel like an internal combustion engine.”

But even without an explosion, the fuel cell must withstand intensive working conditions.

“These devices generally operate at temperatures of 700 to 800 degrees Celsius, and they have to do this for a long time – 40,000 hours in their lifetime,” Nicholas said. By comparison, this is about 1,300 to 1,400 degrees Fahrenheit, or about twice the temperature of a commercial pizza oven.

“And during that lifetime you rolled it hot,” Nicholas said. “You cool it and reheat it. It’s a very intense environment.

So one of the drawbacks of this advanced technology is quite basic: the conductive circuit, which is often made of silver, must adhere better to the ceramic components beneath it.

The researchers found that the secret to improving adhesion was the addition of a porous middle layer of porous nickel between silver and ceramics.

Through computer experiments and simulations, the interaction between materials optimized the nickel deposition team on the ceramic. Researchers turned to screen printing to create thin, porous layers of nickel in a pattern or design of their choice on ceramics.

Innovative properties of crystalized silicon

“This is the same screen printing used to make T-shirts,” Nicholas said. “We only print electronics instead of shirts. This is a complete manufacturing technology.”

Once the nickel is in place, the team contacts it with silver that has melted at about 1,000 degrees Celsius. Not only does nickel withstand this heat – its melting point is 1455 degrees Celsius – but it also distributes liquid silver evenly over its delicate structures thanks to its so-called capillary effect.

“It’s almost like a tree,” Nicholas said. “A tree uses capillary action to get water into its branches. Nickel uses the same mechanism to wet molten silver.”

As silver cools and solidifies, it retains nickel on the ceramic, even at 700 to 800 ° C, where it is placed in a solid oxide fuel cell or solid oxide electrolysis cell. And this approach can also help other technologies in which electronics are hot.

“There are a variety of electronic applications that require a printed circuit board that can withstand high temperatures or high power,” said Jon Debling, director of technology at MSU Technologies, Michigan’s Office of Technology Transfer and Commercialization. “This includes programs in the automotive, aerospace, industrial and military sectors, but also newer applications such as solar cells and solid oxide fuel cells.”

As a technology director, Debling is working to commercialize Sparta’s innovations and is patenting the process to make more robust electronics.

“This technology – in terms of cost and temperature stability – is significantly more advanced than existing paste and vapor deposition technologies,” he said.

For his part, Nicholas remains most interested in these innovative programs, such as solid oxide fuel cells and solid oxide electrolyte cells.

“We’re trying to increase their reliability on Earth – and on Mars,” Nicholas said.

“The interest in hexagonal silicon dates back to the 1960s because of the possibility of having adjustable electronic properties that could improve performance beyond the cube shape,” Stroebel explained.

Silicon hexagonal shapes were synthesized earlier, but only through the deposition of thin films or as nanocrystals that coexist with irregular materials. The newly demonstrated Si24 pathway produces the first high-quality bulk crystals that serve as a basis for future research activities.

Above and beyond conventional use

Using PALLAS advanced computer tools, previously frozen by team members to predict structural transmission paths – such as how water freezes when steam evaporates or freezes – the group can understand the transfer mechanism from Si24 to 4H Was. Understand the Si and the structural relationship that allows the preservation of highly oriented product crystals.

“In addition to expanding our fundamental control over the synthesis of new structures, the discovery of 4H silicon bulk crystals opens the door to an exciting future research perspective for adjusting optical and electronic properties through strain engineering and elemental replacement,” Schill said. “We could potentially use this method to create seed crystals to grow large amounts of 4H structure with properties that may be greater than the properties of silicon diamonds.”

Article by:

Armin Vali

Adapted from:

Science daily.

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