Aluminum metal and silica glass react chemically as they are heated and drawn, producing a fiber with a core of pure, crystalline silicon — the raw material of computer chips and solar cells — and a coating of silica.
It turned out that the chemical reaction in the fiber was a well-known one: At the high temperatures used for drawing the fiber, about 2,200 degrees Celsius, the pure aluminum core reacted with the silica, a form of silicon oxide. The reaction left behind pure silicon, concentrated in the core of the fiber, and aluminum oxide, which deposited a very thin layer of aluminum between the core and the silica cladding.
Now, Hou says, “We can use this to get electrical devices, like solar cells or transistors, or any silicon-based semiconductor devices, that could be built inside the fiber.” Many teams have tried to create such devices within fibers, he says, but so far all of the methods tried have required starting with expensive, high-purity silicon.
“Now we can use an inexpensive metal,” Hou says. “It gives us a new approach to generating a silicon-core fiber.”
“We want to use this technique to generate not only silicon inside, but also other materials,” Hou says. In addition, the team is working to produce specific structures, such as an electrical junction inside the material as it is drawn. “We could put other metals in there, like gold or copper, and make a real electrical circuit,” he says.
Nature Communications - Crystalline silicon core fibres from aluminium core preforms