Properties: gray metallic luster. The density is 2.32~2.34. The melting point is 14 10℃. The boiling point is 2355℃. Soluble in mixed acid of hydrofluoric acid and nitric acid, insoluble in water, nitric acid and hydrochloric acid. The hardness is between germanium and aging, which is brittle at room temperature and easy to break when cutting. It is tough when heated above 800℃, and obviously deformed at 1300℃. Inactive at room temperature, it reacts with oxygen, nitrogen and sulfur at high temperature. In the high-temperature melting state, it has great chemical activity and can interact with almost any substance. With semiconductor properties, it is an extremely important and excellent semiconductor material, but a small amount of impurities can greatly affect its conductivity. In the electronic industry, it is widely used as the basic material for making transistor radios, tape recorders, refrigerators, color TVs, video recorders and electronic computers. It is obtained by chlorination of dry silicon powder and dry hydrogen chloride gas under certain conditions, followed by condensation, rectification and reduction.
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Question 2: What is polysilicon used for? Mainly used in solar panels, but also artificial intelligence, automatic control, information processing, photoelectric conversion and other semiconductor devices of electronic information basic materials. Polysilicon is a good semiconductor.
Question 3: What is polysilicon? Name: monocrystalline silicon
English name: monocrystalline silicon
Molecular formula: Si
Silicon single crystal. A crystal with a basically complete lattice structure. Different directions have different properties, so they are good semiconductor materials. The purity requirement is 99.9999%, even above 99.9999%. Used for manufacturing semiconductor devices, solar cells, etc. It is extracted from high-purity polysilicon in a single crystal furnace.
When molten elemental silicon solidifies, silicon atoms are arranged into many crystal nuclei in the diamond lattice. If these crystal nuclei grow into grains with the same crystal plane orientation, these grains combine in parallel and crystallize into monocrystalline silicon. Monocrystalline silicon has the physical properties of metalloid and weak conductivity, and the conductivity increases with the increase of temperature, so it has obvious semiconductivity. Ultrapure monocrystalline silicon is an intrinsic semiconductor. Doping trace amounts of group Ⅲ A elements, such as boron, into ultra-pure single crystal silicon can improve its conductivity and form a P-type silicon semiconductor. If a small amount of ⅴ A group elements, such as phosphorus or arsenic, are added, the conductivity can also be improved and N-type silicon semiconductors can be formed. The preparation method of monocrystalline silicon is usually to prepare polycrystalline silicon or amorphous silicon first, and then grow rod-shaped monocrystalline silicon from the melt by Czochralski method or suspension zone melting method. Monocrystalline silicon is mainly used to manufacture semiconductor components.
Uses: It is the raw material for manufacturing semiconductor silicon devices, used for manufacturing high-power rectifiers, high-power transistors, diodes, switching devices, etc.
Monocrystalline silicon is a relatively active nonmetallic element, which is an important part of crystal materials and is at the forefront of the development of new materials. Its main uses are as semiconductor materials and solar photovoltaic power generation, heating and so on. Because solar energy has many advantages such as cleanliness, environmental protection and convenience, in the past 30 years, solar energy utilization technology has made great progress in research and development, commercial production and market development, and has become one of the fast and stable emerging industries in the world.
Monocrystalline silicon construction projects have a huge market and broad development space. The content of silicon in the crust reaches 25.8%, which provides an inexhaustible source for the production of monocrystalline silicon.
In recent years, the development of various crystal materials, especially high-tech value-added materials represented by monocrystalline silicon and related high-tech industries, has become the pillar of the contemporary information technology industry, and has made the information industry the fastest-growing leading industry in the global economy. As a potential high-tech resource, monocrystalline silicon is attracting more and more attention.
Question 4: What is the purpose of polysilicon? Polysilicon is divided into electronic grade and solar grade.
Let's talk about the solar energy level first. As the raw material of the solar energy industry chain, we cast ingots or pull monocrystalline silicon rods, and then cut them into silicon wafers to produce solar panels, that is, solar panels on satellites and space stations. Most of them are still used in solar power plants under construction. There are few solar power stations in China, which are very environmentally friendly, but the cost is high and the electricity bill is expensive, so subsidies from * * are often needed. Europe is the largest solar energy user in the world, and it is also the solar energy attack board of China.
Electronic-grade polysilicon is used to produce semiconductor materials, mainly used in electronic equipment and widely used in chips.
Question 5: What is the use of polysilicon? The demand for polysilicon mainly comes from semiconductors and solar cells. The final use of polysilicon is mainly to produce integrated circuits, discrete devices and solar cells.
Question 6: What is the difference between monocrystalline silicon and polycrystalline silicon? Polycrystalline silicon is the direct raw material for producing monocrystalline silicon, and it is the basic electronic information material for contemporary semiconductor devices such as artificial intelligence, automatic control, information processing and photoelectric conversion. Known as "the cornerstone of microelectronic architecture".
Monocrystalline silicon and polycrystalline silicon also play a great role in the utilization of solar energy. Although at present, in order to make solar power generation have a bigger market and be accepted by consumers, it is necessary to improve the photoelectric conversion efficiency of solar cells and reduce the production cost. From the current development history of international solar cells, it can be seen that their development trends are monocrystalline silicon, polycrystalline silicon, ribbon silicon and thin film materials (including microcrystalline silicon-based films, compound-based films and dye films).
From the perspective of industrial development, the center of gravity has developed from single crystal to polycrystalline, the main reasons are as follows; [1] There are fewer and fewer head and tail materials available for solar cells; [2] For solar cells, the square substrate is more cost-effective, and the square material can be directly obtained by casting polysilicon which is directly solidified; [3] Polycrystalline silicon production technology has been continuously improved. The fully automatic casting furnace can produce more than 200 kilograms of silicon ingots per production cycle (50 hours), and the grain size reaches centimeter level; [4] Due to the rapid development of monocrystalline silicon technology in recent ten years, this technology has also been applied to the production of polycrystalline silicon batteries, such as selective etching of emitter junction, back field, textured etching, surface and bulk passivation, fine metal gate electrode and so on. Using screen printing technology can reduce the width of gate electrode to 50 microns, and the height can reach more than 65438 05 microns. Using rapid thermal annealing technology to produce polysilicon can greatly shorten the process time. The thermal process time of a single chip can be completed in one minute, and the battery conversion efficiency made by this process on a piece of polysilicon chip with 100 square centimeter exceeds 14%. It is reported that the efficiency of the battery fabricated on the 50 ~ 60 micron polysilicon substrate currently exceeds 16%. Using mechanical slotting and brushing technology, the efficiency of 65,438+000 square centimeters polycrystalline body exceeds 65,438+07%, and the efficiency without mechanical slotting is 65,438+06% in the same area. By adopting the buried gate structure, the battery efficiency of mechanically slotting on a polycrystalline body of 65,438+030 cm 2 is 65,438+05.8%.
The difference between monocrystalline silicon and polycrystalline silicon is that when molten elemental silicon solidifies, silicon atoms are arranged into many crystal nuclei in a diamond lattice. If these crystal nuclei grow into grains with the same crystal plane orientation, monocrystalline silicon is formed. If these nuclei grow into grains with different crystal orientations, polysilicon is formed. The difference between polysilicon and monocrystalline silicon is mainly manifested in physical properties. For example, polysilicon is inferior to monocrystalline silicon in mechanical and electrical properties. Polycrystalline silicon can be used as raw material for drawing monocrystalline silicon. Monocrystalline silicon can be regarded as the purest substance in the world, and the general semiconductor devices require the purity of silicon to be above six nines. The requirements of large-scale integrated circuits are higher, and the purity of silicon must reach nine nines. At present, people have been able to produce monocrystalline silicon with a purity of 129. Monocrystalline silicon is an indispensable basic material in modern science and technology such as electronic computers and automatic control systems.
Question 7: What are the specifications of polysilicon? 30-point polysilicon has specifications such as electronic grade and solar grade. The following are solar-grade specifications.
Polycrystalline silicon has a gray metallic luster with a density of 2.32~2.34g/cm3. The melting point is 14 10℃. The boiling point is 2355℃. Soluble in mixed acid of hydrofluoric acid and nitric acid, insoluble in water, nitric acid and hydrochloric acid. The hardness is between germanium and aging, which is brittle at room temperature and easy to break when cutting. It is tough when heated above 800℃, and obviously deformed at 1300℃. Inactive at room temperature, it reacts with oxygen, nitrogen and sulfur at high temperature. In the high-temperature melting state, it has great chemical activity and can interact with almost any substance. With semiconductor properties, it is an extremely important and excellent semiconductor material, but a small amount of impurities can greatly affect its conductivity. In the electronic industry, it is widely used as the basic material for making transistor radios, tape recorders, refrigerators, color TVs, video recorders and electronic computers. It is obtained by chlorination of dry silicon powder and dry hydrogen chloride gas under certain conditions, followed by condensation, rectification and reduction.
Question 8: What are the raw materials for polysilicon production? The raw materials for polysilicon production are trichlorosilane and hydrogen, which are put into a reduction furnace according to a certain proportion, and undergo thermal decomposition and reduction reactions to produce polysilicon rods.
Trichlorosilane is produced by the reaction of hydrogen chloride and industrial silicon powder in a synthesis furnace,
Hydrogen chloride is produced by the combustion of hydrogen and chlorine in chlorination storage and synthesis furnace.
Chlorine gas is produced by electrifying the industrial brine of sodium chloride.
Reacting with sodium chloride industrial brine by electricity can produce hydrogen.
It can also be produced by electrolysis with water.
Industrial silicon powder is made by the reduction reaction of timely minerals and carbon under the action of electricity, and then crushed into industrial silicon powder.