Monocrystalline silicon, as a relatively reactive non-metallic element crystal, is an important component of crystalline materials and is at the forefront of new material development. The manufacturing process of monocrystalline silicon involves the following steps: quartz sand – metallurgical-grade silicon – purification and refining – deposition of polycrystalline silicon ingots – monocrystalline silicon – silicon wafer cutting. Its main applications are as a semiconductor material and in solar photovoltaic power generation and heating.
Single-crystal silicon possesses quasi-metallic physical properties, exhibiting weak electrical conductivity that increases with temperature, and significant semiconductivity. Ultrapure single-crystal silicon is an intrinsic semiconductor. Doping ultrapure single-crystal silicon with trace amounts of Group IIIA elements, such as boron, can improve its conductivity, forming a p-type silicon semiconductor; similarly, doping with trace amounts of Group VA elements, such as phosphorus or arsenic, can improve conductivity, forming an n-type silicon semiconductor.
Main uses of monocrystalline silicon
Monocrystalline silicon is mainly used to make semiconductor components. It is the raw material for manufacturing semiconductor silicon devices and is used to make high-power rectifiers, high-power transistors, diodes, switching devices, etc. Now, we can see the presence and role of "silicon" everywhere in our lives. Crystalline silicon solar cells have been the fastest industrialized in the past 15 years.
The earliest application of monocrystalline silicon was in silicon solar cells, which have high conversion efficiency and the most mature technology. They are mostly used in areas with short sunshine hours, low light intensity, and high labor costs, such as the aerospace field. By adopting different silicon wafer processing and cell manufacturing technologies, research institutions and cell manufacturers at home and abroad have produced high-efficiency monocrystalline silicon cells.
Preparation method of single crystal silicon
Currently, the two most widely used methods are the Czochralski method and the crucibleless floating zone melting method. The single-crystal silicon obtained by these two methods is called CZ silicon and FZ silicon, respectively. The production method of single-crystal silicon usually involves first producing polycrystalline silicon or amorphous silicon, and then growing rod-shaped single-crystal silicon from the melt using the Czochralski method or the floating zone melting method.
The preparation of monocrystalline silicon requires a transformation from polycrystalline to monocrystalline, that is, the atoms change directly from a random arrangement in the liquid phase to an ordered array, and from an asymmetric structure to a symmetric structure. This transformation is not a global effect, but is gradually accomplished through the movement of the solid-liquid interface. To achieve the above transformation process, polycrystalline silicon must go through a transformation from solid silicon to molten silicon, and then to solid crystalline silicon. This is the path that must be followed to grow monocrystalline silicon from molten silicon.
