Polysilicon is a form of elemental silicon. When molten elemental silicon solidifies under supercooled conditions, the silicon atoms are arranged in a diamond lattice form into a plurality of crystal nuclei. If the crystal nuclei grow into crystal grains with different crystal orientations, the crystal grains are combined and crystallized into polycrystalline silicon.
Polycrystalline silicon can be used as a raw material for drawing single crystal silicon, and the difference between polycrystalline silicon and single crystal silicon is mainly manifested in physical properties. For example, in terms of anisotropy of mechanical properties, optical properties, and thermal properties, it is much less pronounced than monocrystalline silicon; in terms of electrical properties, polycrystalline silicon crystals are much less conductive than monocrystalline silicon, and even have little conductivity. In terms of chemical activity, the difference between the two is extremely small. Polycrystalline silicon and single crystal silicon can be distinguished from each other in appearance, but the true identification must be determined by analysis of the crystal plane direction, conductivity type, and electrical resistivity.
Utilization value: From the current development process of international solar cells, it can be seen that the development trend is monocrystalline silicon, polycrystalline silicon, ribbon silicon, thin film materials (including microcrystalline silicon-based films, compound-based films and dye films). Polycrystalline silicon is a direct raw material for the production of single crystal silicon, and is an electronic information basic material for semiconductor devices such as artificial intelligence, automatic control, information processing, and photoelectric conversion.