Silicon

About Silicon

Silicon makes up about 28% of the Earth's crust by mass — second only to oxygen — and almost all of it is locked into silicates — SiO₄ tetrahedra sharing corners in feldspars, micas, quartz, clays, and the rest of the rock cycle. As a metalloid with a bandgap of 1.12 eV at room temperature, it is the workhorse of solid-state electronics: everything from CPUs to MOSFET power switches to CMOS image sensors is fabricated on monocrystalline silicon wafers. The route from sand to chip is brutal: quartz is reduced to metallurgical silicon in a submerged-arc furnace, purified through the Siemens process to polycrystalline silicon at 99.9999999% (nine-nines), then pulled into a Czochralski boule and sliced into 300 mm wafers. Beyond electronics, silicon chemistry runs in two big directions. Silicones — polysiloxanes built on Si-O-Si backbones — give you sealants, lubricants, breast implants, and high-temperature gaskets. Aluminosilicate frameworks build zeolites that crack petroleum, soften water, and shape-select catalysis. In biology, diatoms pull dissolved silicic acid from seawater to grow porous opaline shells, and they account for roughly 20% of global photosynthesis.