Single crystal silicon vs Polycrystalline silicon?

Silicon material is the most basic and core material in the semiconductor industry. The complex production process of the semiconductor industry chain should also start from the production of basic silicon material.

In the production of silicon materials, there are two basic concepts: polysilicon and monocrystalline silicon. What exactly do these two mean? What's the difference?

Single crystal silicon

Theoretically, monocrystalline silicon is a form of elemental silicon. When molten elemental silicon is solidified, silicon atoms are arranged in diamond lattice into many crystal nuclei. If these crystal nuclei grow into grains with the same orientation of crystal plane, these grains will be combined in parallel to crystallize into monocrystalline silicon.

Monocrystalline silicon has the physical properties of a quasi-metal and has weak electrical conductivity, which increases with the increase of temperature. At the same time, monocrystalline silicon also has significant semi-electrical conductivity. Ultra-pure monocrystalline silicon is an intrinsic semiconductor. The conductivity of ultra-pure monocrystal silicon can be improved by adding trace ⅢA elements (such as boron), and P-type silicon semiconductor can be formed. Such as adding trace ⅤA elements (such as phosphorus or arsenic) can also improve the degree of conductivity, the formation of N-type silicon semiconductor.

Polycrystalline silicon

As for polysilicon, according to Wikipedia, polysilicon is a material made of tiny, monocrystalline silicon. It differs from monocrystalline silicon, which is used in electronics and solar cells, and from amorphous silicon, which is used in thin-film devices and solar cells.

The difference between the Single crystal silicon vs Polycrystalline silicon

The difference in appearance

The four corners of the monocrystalline silicon cell are arc shaped, and there is no pattern on the surface. Monocrystalline silicon dark blue, almost black; The four corners of the polycrystalline silicon cell show square corners, and the surface has a pattern similar to the ice flower. The polycrystalline silicon sky blue, bright color.

Use the distinction above

For the user, there is no big difference between monocrystalline silicon cells and polycrystalline silicon cells, which have good life and stability. The average conversion efficiency of monocrystalline silicon cell is higher than that of polycrystalline silicon, but the current price is also higher than that of polycrystalline silicon.

The difference in manufacturing process

Polycrystalline cells have fewer production processes than single-crystal cells, so the energy consumed in the manufacturing process of polycrystalline silicon solar cells is slightly less than that of monocrystalline silicon solar cells. However, single-crystal battery modules generate more electricity, so there is little difference in energy consumption ratio after comprehensive calculation.

Comparison of single crystal and polycrystal

The application of monocrystalline photovoltaic panel is earlier than that of polycrystalline photovoltaic panel. The current situation is that the application of polycrystalline silicon in power station is much higher than that of monocrystalline silicon, which accounts for 30% and polycrystalline silicon accounts for 70%. Conversion rate, single crystal efficiency is higher than polycrystal, about 10%-20%. The cost of single crystal is slightly more expensive than that of polycrystal, and the cost of different manufacturers is different. The market price of a watt is five cents to ten cents. The measured data of the attenuation degree show that single crystal and polycrystal have their own advantages, and it is impossible to distinguish the attenuation speed from the Angle of single crystal and polycrystal. Relatively speaking, product quality (sealing degree, whether there is a magazine, whether there is a hidden crack) has a greater impact on the attenuation degree. At present, the performance ratio of polycrystal is slightly higher than that of single crystal, but only at present. With the reduction of the cost of single crystal components, it is possible to reverse in a few years.