Preparation method of gallium-doped silicon ingot, gallium-doped silicon ingot and silicon piece

Abstract

The invention discloses a preparation method of a gallium-doped silicon ingot, the gallium-doped silicon ingot and a silicon piece. The preparation method comprises the following steps: injecting a molten metal gallium into pores of a silicon material, curing the molten metal gallium and/or sealing the pores, putting the obtained silicon material with the metal gallium and the rest silicon material into a quartz crucible, and performing melting, recrystallization and annealing cooling so as to obtain gallium-doped silicon ingot. The gallium-doped silicon ingot is prepared by using the preparation method. The silicon piece is prepared from the gallium-doped silicon ingot. By adopting the preparation method, a gallium doping process and effective and precise control on gallium doping amountscan be achieved, the preparation method has the advantages of being convenient in operation, easy in control, high in gallium doping amount precision, and the like, the prepared gallium-doped siliconingot has the advantages of being good in resistance distribution uniformity, long in minority carrier lifetime, and the like, a solar battery prepared from the gallium-doped silicon ingot has high photoelectric efficiency and low light degradation, and great significances can be achieved for wide application of solar batteries.

Description

technical field [0001] The invention belongs to the field of preparation of crystalline silicon materials and semiconductor silicon materials for solar cells, and relates to a preparation method of gallium-doped silicon ingots, gallium-doped silicon ingots and silicon wafers. Background technique [0002] In the field of crystalline silicon material manufacturing, whether it is a single crystalline silicon material or a polycrystalline silicon material, a boron-doped P-type crystalline silicon solar cell will have a light-induced degradation (LID) problem when it is used. With the continuous development of crystalline silicon cell technology, the requirements for its substrate materials are getting higher and higher, and the pursuit of solar cells with higher efficiency and lower light attenuation is the eternal pursuit of the industry. Gallium-doped technology has been proven to significantly reduce the light-induced attenuation of crystalline silicon cells, and has been in...

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Problems solved by technology

However, since the melting point of gallium is about 29.8°C, and its melting point is relatively low, the following problems may occur in the preparation process of gallium-doped crystalline silicon: (1) metal gallium presents a large solid shape during batching, and its weight is difficult to measure, and The measurement accuracy is not high, which affects the resistivity value of crystalline silicon

(2) In the melting process of crystalline silicon preparation, which includes low-temperature vacuum process and high-temperature low-pressure air circulation process, liquid gallium is relatively easy to volatilize, resulting in less gallium actually entering the growth stage, and the resistivity of the prepared crystalline silicon material There are large fluctuations

Although this method discloses the use of gallium-silicon dopant blocks to prepare gallium-doped polycrystalline silicon ingots, it uses gallium oxide and silicon to react to form silicon-gallium alloys, which does not have the theoretical feasibility of chemical reactions, and also introduces high-soluble oxygen, which cannot It is used to prepare doped alloys of crystalline silicon; in this patented technology, during the preparation of crystalline silicon, the gallium-silicon dopant block needs to be partially melted, and its melting amount is not easy to control, resulting in extremely high gallium content in the silicon solution. Large uncertainties, affecting the quality of the prepared crystalline silicon material

[0004] The Chinese patent document with the publication number CN 108315819 A discloses a polycrystalline gallium-doped silicon wafer and its preparation method and a solar cell. The polycrystalline gallium-doped silicon wafer prepared by doping gallium has a relatively low light attenuation ratio, However, the light attenuation rate of polycrystalline gallium-doped silicon wafers fluctuates greatly in this patent, for example, the lowest value of light attenuation ratio is 0.5%, and the highest value is 1.7%. In addition, the process of doping gallium is not carried out in this patent technology optimization, which leads to an uncertainty in the solubility of gallium

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