Silicon dioxide, or sand, makes up about 40 percent of the earth's crust, but the industrial method for converting sand into crystalline silicon is expensive and has a major environmental impact due to the extreme processing conditions.
"The crystalline silicon in modern electronics is currently made through a series of energy-intensive chemical reactions with temperatures in excess of 2,000 degrees Fahrenheit that produces a lot of carbon dioxide," said Stephen Maldonado, professor of chemistry and applied physics.
Recently, Maldonado and chemistry graduate students Junsi Gu and Eli Fahrenkrug discovered a way to make silicon crystals directly at just 180 F, the internal temperature of a cooked turkey. And they did it by taking advantage of a phenomenon you can see right in your kitchen.
When water is super-saturated with sugar, that sugar can spontaneously form crystals, popularly known as rock candy.
"Instead of water, we're using liquid metal, and instead of sugar, we're using silicon," Maldonado said.
Maldonado and colleagues made a solution containing silicon tetrachloride and layered it over a liquid gallium electrode. Electrons from the metal converted the silicon tetrachloride into raw silicon, which then dissolved into the liquid metal.
"The liquid metal is the key aspect of our process," Maldonado said. "Many solid metals can also deliver electrons that transform silicon tetrachloride into disordered silicon, but only metals like gallium can additionally serve as liquids for silicon crystallization without additional heat."
The researchers reported dark films of silicon crystals accumulating on the surfaces of their liquid gallium electrodes. So far, the crystals are very small, about 1/2000th of a millimeter in diameter, but Maldonado hopes to improve the technique and make larger silicon crystals, tailored for applications such as converting light energy to electricity or storing energy. The team is exploring several variations on the process, including the use of other low-melting-point metal alloys.
If the approach proves viable, the implications could be huge, especially for the solar energy industry. Crystalline silicon is presently the most-used solar energy material, but the cost of silicon has driven many researchers to actively seek alternative semiconductors.
"It's too premature to estimate precisely how much the process could lower the price of silicon, but the potential for a scalable, dramatically less expensive and more environmentally benign process is there," Maldonado said. "The dream ultimately is to go from sand to crystalline silicon in one step. There's no fundamental law that says this can't be done."
The study, which appears in the Journal of the American Chemical Society, was funded by the American Chemical Society Petroleum Research Fund.
The university is pursuing patent protection for the intellectual property and is seeking commercialization partners to help bring the technology to market.
The study is titled "Direct Electrodeposition of Crystalline Silicon at Low Temperatures" (DOI: 10.1021/ja310897r): http://dx.doi.org/10.1021/ja310897r
Stephen Maldonado's lab group: www.umich.edu/~mgroup
Kate McAlpine | EurekAlert!
Chains of nanogold – forged with atomic precision
23.09.2016 | Suomen Akatemia (Academy of Finland)
Self-assembled nanostructures hit their target
23.09.2016 | King Abdullah University of Science and Technology
The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.
“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...
With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.
Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...
For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.
Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...
At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.
In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...
Every three years, the plastics industry gathers at K, the international trade fair for plastics and rubber in Düsseldorf. The Fraunhofer Institute for Laser Technology ILT will also be attending again and presenting many innovative technologies, such as for joining plastics and metals using ultrashort pulse lasers. From October 19 to 26, you can find the Fraunhofer ILT at the joint Fraunhofer booth SC01 in Hall 7.
K is the world’s largest trade fair for the plastics and rubber industry. As in previous years, the organizers are expecting 3,000 exhibitors and more than...
23.09.2016 | Event News
20.09.2016 | Event News
16.09.2016 | Event News
23.09.2016 | Life Sciences
23.09.2016 | Health and Medicine
23.09.2016 | Life Sciences