I would like to ask the solar cell (silicon) production process is the principle of how
Solar cell production processThe production process of solar cell can be divided into three parts: silicon wafer testing, surface texturing, diffusion bonding, phosphorus removal, silica glass, plasma etching, antireflection coating, screen printing, rapid sintering and so on. Details are as follows:
Two, the surface of cashmereThe preparation of single crystal silicon wafer is the use of anisotropic etching of silicon on the surface of the silicon per square centimeter to form several million square pyramidal structure, namely, the Pyramid structure. Due to the multiple reflection and refraction of incident light on the surface, the absorption of light is increased, and the short circuit current and conversion efficiency are improved. Anisotropic etching of silicon in alkaline solution liquid is usually hot, available alkali sodium hydroxide, potassium hydroxide, lithium hydroxide and ethylenediamine etc.. Most of them were prepared by using dilute sodium hydroxide solution with a concentration of about 1%, and the corrosion temperature was 70-85. In order to obtain a uniform texture, but also in the solution add alcohols such as ethanol and isopropanol as complexing agent to accelerate the corrosion of silicon. In the preparation of velvet, the silicon chip must be first surface corrosion, alkaline or acidic etching solution to about 20 ~ 25 m, corrosion in the face, the general chemical cleaning. After surface preparation of silicon wafers are not suitable for long-term storage in the water, in order to prevent contamination, should be spread as soon as possible.
Silicon wafer detectionSilicon wafer is the carrier of solar cell, the quality of silicon wafer directly determines the conversion efficiency of solar cell. This procedure is mainly used to measure the technical parameters of silicon wafer on line. These parameters mainly include the surface roughness of the silicon wafer, the lifetime of the minority, the resistivity, the P/N type and the micro crack. The device is divided into four parts: automatic loading and unloading, silicon wafer transmission, system integration part and. The silicon photovoltaic detector on the silicon wafer surface roughness were detected, and the size and appearance of diagonal parameter detection chip; micro crack detection module is used to detect silicon micro cracks; another two detecting module, one online test module to test wafer resistivity and wafer type, another module for lifetime test wafer. The detection of the diagonal and micro cracks of the silicon wafer is needed before the sub lifetime and resistivity measurement. Wafer inspection equipment can automatic loading and unloading, and substandard products in a fixed position, so as to improve the detection accuracy and efficiency.
Three, diffusion systemSolar cells require a large area of PN junction to achieve the conversion of light energy to electrical energy, while the diffusion furnace is a special equipment for manufacturing solar cell PN junction. Tube type diffusion furnace is mainly composed of quartz boat download four parts part, gas chamber, a furnace body part and a holder part etc.. Generally, the liquid source of three phosphorus oxychloride is used as the diffusion source. The P type silicon wafer is placed in a quartz tube of a tube type diffusion furnace, and three nitrogen oxychloride is used in the quartz vessel at the temperature of 850---900 degrees Celsius, and the phosphorus atom is obtained through the reaction of the phosphorus oxychloride and the silicon wafer through the reaction of the phosphorus and the phosphorus. After a certain time, the phosphorus atom from the surrounding surface layer into a silicon wafer, and wafer to internal diffusion through the void between the silicon atoms, forming a N type semiconductor and P type semiconductor interface, namely PN junction. The PN junction made by this method has good uniformity, the uniformity of box resistance is less than ten percent, and the lifetime of less than 10ms. The manufacture of PN junction is the most basic and most important process in the production of solar cells. Because it is the formation of PN junction, so that the electrons and holes in the flow is no longer back to the original place, so that the formation of the current, using the wire will lead to the current, dc.
