Silicon that has an ordered atomic structure. It is used in almost all integrated circuits in the electronics industry. Fabricated from quartzite, a pure form of sand, the quartzite is treated (see below) to create polycrystalline silicon (polysilicon), a very pure silicon with multiple single-crystal regions of different sizes and orientations. The polysilicon is used to "grow" a single-crystal (monocrystalline) ingot that is sliced into wafers.
From Quartzite to Polysilicon
A common method of creating polysilicon is to mix quartzite with carbon materials in order to produce a very pure silicon that is then exposed to hydrogen chloride. This yields trichlorosilane, which is decomposed by an electric current in a chamber. The result is rods of polycrystalline silicon, which become the raw material for the crystal pulling process that creates the ingots. Contrast with
amorphous silicon. See
polysilicon.