What is the difference between monocrystalline silicon and polycrystalline silicon?

1: What is polysilicon?

Polysilicon is a form of elemental silicon. When molten elemental silicon solidifies under supercooling conditions, silicon atoms are arranged in the form of diamond lattices to form many crystal nuclei. If these crystal nuclei grow into grains with different crystal plane orientations, these grains combine to form polysilicon.

Polysilicon has a gray metallic luster and a hardness between germanium and quartz. It is brittle at room temperature and easy to break when cut. It becomes ductile when heated to above 800°C and shows obvious deformation at 1300°C.

Polysilicon has semiconductor properties and is an extremely important and excellent semiconductor material. It is widely used in the electronics industry as a basic material for manufacturing semiconductor radios, tape recorders, refrigerators, color TVs, video recorders, and electronic computers.

The two main methods for preparing polysilicon are: modified Siemens method and silane preparation method

In the solar industry, polysilicon can be used as a cell material after being made into silicon wafers, and is also the main material for preparing single crystal silicon.

2: What is granular silicon?

Granular silicon is called granular polycrystalline silicon, which is a form of polycrystalline silicon. It is produced by the silane method. Compared with block silicon, granular silicon reduces the crushing link and has low impact loss on the inner wall of the quartz feeding barrel. Granular silicon has good filling properties, and the feeding barrel can be filled with 15-20% more granular silicon. The main advantages of granular silicon are that carbon emissions are reduced by 74%, power consumption is reduced, and unit manufacturing costs can be reduced by 20-30%.

3: What is single crystal silicon?

Single crystal silicon is a form of elemental silicon, usually referring to a substance formed by silicon atoms in an arranged form.

When molten elemental silicon solidifies, silicon atoms are arranged into crystal nuclei in a diamond lattice, and the crystal nuclei grow into grains with the same crystal plane orientation to form single crystal silicon.

Single crystal silicon is a relatively active non-metallic element crystal with the physical properties of a metalloid. Its conductivity is weak, and its conductivity increases with increasing temperature, and it has significant semi-conductivity.

Ultrapure monocrystalline silicon is an intrinsic semiconductor. By adding certain specific elements, its conductivity can be improved to form P-type silicon semiconductor or N-type silicon semiconductor.

Monocrystalline silicon is a good semiconductor material that can be used to manufacture semiconductor devices such as high-power transistors, diodes, switching devices, etc.

Monocrystalline silicon is also commonly used to manufacture solar cells.

The manufacturing of monocrystalline silicon materials goes through the following processes: quartz sand-metallurgical grade silicon-purification and refining-deposition of polycrystalline silicon ingots-monocrystalline silicon-silicon wafer cutting.

Monocrystalline silicon solar cells are currently commonly used photovoltaic power generation materials with high photoelectric conversion efficiency. They are widely used in transportation, communications, aerospace and other fields.

4: What is the difference between monocrystalline silicon and polycrystalline silicon?

1. Difference in appearance

Monocrystalline silicon: The cell is square, rounded, and dark blue;

Polycrystalline silicon: The cell is square and sky blue.

2. Comparison of the monocrystalline silicon and polycrystalline silicon cell preparation industry chain

The difference between monocrystalline and polycrystalline lies mainly in the preparation of raw materials. Monocrystalline silicon is prepared by the direct pull method, while polycrystalline silicon is prepared by the ingot casting method. There are only some minor differences in the back-end manufacturing process.

3. Difference in crystal quality

Single crystal silicon wafer is a complete lattice arrangement;

Polycrystalline silicon wafer is a combination of multiple tiny single crystals.

4. Difference in conversion rate:

Single crystal silicon: Photoelectric conversion efficiency is 16-18%, and the highest conversion rate in the laboratory can reach 25%. It has high photoelectric conversion efficiency, high reliability, and slightly higher power generation;

Polycrystalline silicon: Photoelectric conversion efficiency is 14-16%, and the highest conversion rate in the laboratory can reach 20.4%. At present, the production technology of polycrystalline silicon is mature, and the production cost is lower than that of single crystal silicon.