University of Michigan makes crystalline silicon from liquid metal

Researchers at the University of Michigan have just invented a new way to make crystalline silicon in liquid metal. Thereby, important components in computers and solar cells promise to be cheaper and more environmentally friendly.

Silicon dioxide, or sand, accounts for 40% of the Earth's crust. However, the method of converting from sand to industrial crystalline silicon is costly and causes great impact on the environment due to harsh treatment conditions.

According to Stephen Maldonado, professor of chemistry and applied physics, "crystalline silicon in modern electronic devices today is being produced through a series of chemical reactions that carry large amounts of energy with normal temperatures." over 2000 degrees Fahrenheit (1093 degrees C) and emitting a large amount of Carbon dioxide ".

Recently, Maldonado and Junsi Gu chemistry graduates and Eli Fahrenkrug discovered a way to create silicon crystals directly at temperatures of only 180 degrees F (82 degrees C), equivalent to heat. interior degree of a chicken rotary oven.

As you can imagine, when the water reaches the state of super saturation with sugar, the sugar can automatically crystallize."But instead of using water, we use liquid metal and instead of sugar, we use Silicon," explained Professor Maldonado.

Maldonado and his colleagues created a solution containing Silicon tetrachloride and they were layered on a liquid Gallium electrode. The electrons from the metal convert Silicon tetrachloride into raw Silicon, which is then dissolved into liquid metal.

"Liquid metal is an important key to this process," Maldonado said. "Many types of solid metals can also provide electrons that convert silicon tetrachloride into dissolved silicon but only metals like Gallium can act as a liquid for crystallizing silicon without generating heat." .

The results of the research team are dark colored films of silicon crystallized on the surface of liquid metal electrodes. Until now, these crystals were very small with a diameter of only about 1 / 2000mm, but Maldonado hoped to improve the technique to create larger silicon crystals, which could be applied to applications such as transfer convert light energy to electricity or store energy. The team is currently continuing to implement the process according to various variations, including the use of low-melting metal alloys outside of Gallium.

If Maldonado's approach proves potential, there will be a lot of applications waiting ahead, especially for the solar industry. Crystal silicon is by far the most commonly used material for solar exploitation, but high production costs have forced researchers to look for alternative semiconductors.

"It is still too early to accurately predict how much this process will reduce the cost of Silicon, however, the potential for a large-scale production process, which is not too expensive and environmentally friendly. "Our final desire is to be able to convert from sand to crystalline silicon in a single step. And without any basic rules saying that this can't be done," Said Maldonado.

Research on how Maldonado's silicon-based liquid-crystal silicon has been published in the American Chemistry Society magazine is being raised by the American Petroleum Society's Petroleum Research Fund. In addition, the University of Michigan has filed intellectual property protection and sought commercial partners to bring technology into the market.