(Press-News.org) ANN ARBOR—A new way of making crystalline silicon, developed by U-M researchers, could make this crucial ingredient of computers and solar cells much cheaper and greener.
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.
INFORMATION:
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
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PHILADELPHIA—Infectious diseases in Ghana tend to capture the most attention, but a quiet crisis may soon take over as the country's most threatening epidemic: cancer.
A new study published in January in the journal BMC Cancer, led by Kosj Yamoah, M.D., Ph.D., a resident in the Department of Radiation Oncology at Thomas Jefferson University and Hospital, takes aim at the issue by investigating prostate cancer diagnoses and treatment delivery in black men living in the West African region, in order to devise research strategies to help improve health outcomes.
Overall, ...
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According to Yunchuan "Frank" Liu, a retailer's strategic manipulation of store layout is driven by an incentive to balance the shopping process of "fit-uncertain consumers" and the pricing behavior of upstream suppliers.
"Retailers face two different kinds of markets – the consumers who buy goods, and the manufacturers that supply goods," ...
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When NASA's Aqua satellite passed over the eastern side of the remnants of Tropical Cyclone Oswald the Atmospheric Infrared Sounder (AIRS) instrument captured an infrared image of a powerful band of thunderstorms over the Coral Sea. The band of thunderstorms east of Oswald's center showed some strong convection and ...
Flying high over Antarctica, a NASA long duration balloon has broken the record for longest flight by a balloon of its size.
The record-breaking balloon, carrying the Super Trans-Iron Galactic Element Recorder (Super-TIGER) experiment, has been afloat for 46 days and is on its third orbit around the South Pole.
"This is an outstanding achievement for NASA's Astrophysics balloon team," said John Grunsfeld, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. "Keeping these huge balloons aloft for such long periods lets us do ...
Irvine, Calif. (Corrected version) — Exposing pregnant mice to low doses of the chemical tributyltin (TBT) – which was used in marine antifouling paints and is used as an antifungal agent in some paints, certain plastics and a variety of consumer products – can lead to obesity for multiple generations without subsequent exposure, a UC Irvine study has found.
After exposing pregnant mice to TBT at low concentrations, similar to those found in the environment and in humans, researchers observed increased body fat, liver fat and fat-specific gene expression in liver and ...
In a development that could lead to faster and more effective toxicity tests for airborne chemicals, scientists from Rice University and the Rice spinoff company Nano3D Biosciences have used magnetic levitation to grow some of the most realistic lung tissue ever produced in a laboratory.
The research is part of an international trend in biomedical engineering to create laboratory techniques for growing tissues that are virtually identical to those found in people's bodies. In the new study, researchers combined four types of cells to replicate tissue from the wall of ...
Pulsars—tiny spinning stars, heavier than the sun and smaller than a city—have puzzled scientists since they were discovered in 1967.
Now, new observations by an international team, including University of Vermont astrophysicist Joanna Rankin, make these bizarre stars even more puzzling.
The scientists identified a pulsar that is able to dramatically change the way in which it shines. In just a few seconds, the star can quiet its radio waves while at the same time it makes its X-ray emissions much brighter.
The research "challenges all proposed pulsar emission theories," ...
A prospective study led by researchers from the University of California, San Diego School of Medicine has found that low serum vitamin D levels in the months preceding diagnosis may predict a high risk of premenopausal breast cancer.
The study of blood levels of 1,200 healthy women found that women whose serum vitamin D level was low during the three-month period just before diagnosis had approximately three times the risk of breast cancer as women in the highest vitamin D group. The study is currently published online in advance of the print edition of the journal ...
Cincinnati, OH, January 25, 2013 -- Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen, are commonly used to treat pain and reduce fever in children. However, the use of NSAIDs has been shown to cause acute kidney injury (AKI) in some children. A new study scheduled for publication in The Journal of Pediatrics reports the findings on the number of children diagnosed with AKI caused by NSAIDs in one hospital over an 11 ½ year span.
Dr. Jason Misurac and colleagues from the Indiana University School of Medicine and Butler University retrospectively ...
