polycrystalline silicon properties

Polycrystalline silicon is a kind of new form. Molten elemental silicon in cold conditions, the silicon atom to clot grid work arranged in a form of diamond nucleation, such as these forms many grow the grain and different faces orientation is the grain together, into polycrystalline silicon crystals. Polycrystalline silicon can be control of raw materials, polycrystalline silicon and monocrystalline silicon difference is mainly manifested in the physical properties. For example, in the mechanical properties, optical properties and thermal properties of the anisotropic aspects, rather than monocrystalline silicon is obvious; In the electrical properties, polycrystalline silicon crystals in the conductivity of the much less significant, and even almost no single crystal silicon electrical conductivity. In the chemical activity, two tiny differences. Polycrystalline and monocrystalline silicon can be distinguished from the outside, but the real identify must through the analysis of protein crystal orb direction, conductive type and resistivity, etc.
Polycrystalline silicon properties: grey metallic luster. Density 2.32 ~ 2.34. Melting point 1410 ℃. Boiling point 2355 ℃. Soluble in hydrofluoric acid and nitric acid in the mix, insoluble in water, nitric acid and hydrochloric acid. Hardness between ge and quartz, room temperature between very brittle, cutting apart easily. Heated to 800 ℃ above 1300 ℃ is ductility, show obvious when deformation. Under normal temperature, high temperature not lively with oxygen, nitrogen, and sulfur and reaction. High temperature melting state, has large chemical lively and sex, can and almost any material role. Has the properties of semiconductor, is a very important excellent semiconductor materials, but trace impurities can greatly affect its electrical conductivity. Electronic industry are widely used in the manufacturing of transistor radio, tape recorder, refrigerators, TVS, VCRS, electronic computers and other base materials. Silicon powder and dry by dry gas hydrogen in certain conditions, then through condensation, chlorinated distillation, reduction.
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