New Means to Harvest Silicon Crystals

Guest_Jim_* - January 28, 2013 07:04AM in Science & Technology

Silicon is a very common material, but not just in our electronics; it represents 28.2% of the Earth's crust by weight, with only oxygen representing a greater portion. Combined these two elements form silicon dioxide or sand, and that makes up 40% of the crust. With this great abundance it makes sense that we would use silicon as much as we do, but harvesting the silicon is very difficult. Researchers at the University of Michigan however have devised a new, clever way to collect silicon crystals that is much simpler and less expensive.

This new method is almost a combination of two classic experiments (though only one is potentially safe to do at home): supersaturating water with sugar and electrolysis. When you pour sugar into water, it dissolves into the water, to a point. Eventually there will be so much sugar that the water cannot absorb anymore unless you heat it. Then the extra sugar dissolves, supersaturating the water, and when you let it cool, the excess sugar will leave the water as a single, large crystal, commonly called rock candy. The researchers are doing something similar by supersaturating liquid gallium with silicon tetrachloride, but instead of just heating the mixture, they are passing a current through it to free the silicon atoms, similar to how electrolysis separates hydrogen and oxygen in water.

The result of this setup is pure silicon crystals floating on top of the liquid metal. For now those crystals are too small for much use, but the researchers are looking at ways to improve this method, to create larger crystals.

Source: University of Michigan