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Gallium-doped crystalline silicon with uniformly distributed resistivity and preparation method thereof

A technology of resistivity distribution and crystalline silicon, applied in the field of preparation of gallium-doped crystalline silicon, can solve the problems of inability to carry out production and promotion, complex impurity composition, serious silicon wafer compensation, etc.

Active Publication Date: 2015-08-19
JIANGSU XIEXIN SILICON MATERIAL TECH DEV
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Problems solved by technology

[0003] For P-type silicon wafers, gallium-doped silicon wafers have been proven to have no light attenuation, but because the segregation coefficient of gallium in silicon is extremely low, only 0.008, the resistivity distribution of normal gallium-doped silicon ingots in actual production is between 0.1- Between 5Ω.cm, the distribution range is too large, and the qualified part that meets the resistivity between 0.8-3Ω.cm is usually less than 50%, which cannot be promoted for production
However, this method will lead to serious compensation of silicon wafers, and the impurity components in the recycled material are very complex. In addition, the co-doping of boron and gallium cannot completely solve the problem of light attenuation due to the existence of boron, which is the main reason for the inconvenient promotion in actual production.

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  • Gallium-doped crystalline silicon with uniformly distributed resistivity and preparation method thereof

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preparation example Construction

[0020] Please refer to figure 1 , The invention provides a method for preparing gallium-doped crystalline silicon with uniform resistivity distribution, comprising the following steps.

[0021] Step S110, evenly laying a layer of gallium-doped silicon material on the bottom of the crucible. The gallium-doped silicon material can be gallium-doped polycrystalline silicon or gallium-doped monocrystalline silicon, which can be prepared by itself or purchased from the market. This layer of gallium-doped silicon material is also used as a seed crystal for subsequent crystal growth after the silicon material is melted.

[0022] Step S120 , disposing a polysilicon material containing gallium dopant above the gallium-doped silicon material. Continue to put polysilicon material and gallium dopant into the crucible. The gallium dopant can be pure gallium or a silicon-gallium alloy. The mixing degree of the polysilicon material and the gallium dopant is not required, they can be mixed...

Embodiment 1

[0033] Lay 20 kg of granular polysilicon material with a gallium concentration of 200,000 ppbw on the bottom of the crucible. Then put 800kg of primary polysilicon material into the crucible and directly dope 11g of pure gallium at the same time. When melting, a top-down method is adopted, and the measurement is assisted by a quartz rod. When the gallium-doped polysilicon material at the bottom is nearly half melted, crystal growth begins and a crystalline silicon ingot is formed. The electrical resistivity of the crystalline silicon ingot was tested after it came out of the furnace. It was 0.72Ω.cm at a distance of 30mm from the head of the silicon ingot, and 2.21Ω.cm at a distance of 40mm from the tail. The qualified ratio between 0.8 and 3Ω.cm was 68.5%.

Embodiment 2

[0035] Lay 30 kg of granular polysilicon material with a gallium concentration of 12000 ppbw on the bottom of the crucible. Then put 800kg of primary polysilicon material into the crucible, and at the same time directly dope about 10g of pure gallium. When melting, a top-down method is adopted, and the measurement is assisted by a quartz rod. When the gallium-doped polysilicon material at the bottom is nearly half melted, crystal growth begins and a crystalline silicon ingot is formed. The resistivity of the crystalline silicon ingot was tested after it was released from the furnace. It was 0.71Ω.cm at a distance of 30mm from the head of the silicon ingot, and 2.65Ω.cm at a distance of 40mm from the tail. The qualified ratio between 0.8 and 3 was 67.2%.

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Abstract

The invention relates to a preparation method of gallium-doped crystalline silicon with uniformly distributed resistivity. The preparation method comprises the following steps: uniformly laying a layer of gallium-doped silicon material at the bottom of a crucible; arranging a polycrystalline silicon material containing a gallium doping agent above the gallium-doped silicon material; controlling the temperature in the crucible to gradually melt the polycrystalline silicon material and the gallium-doped silicon material from top to bottom, and upwards crystallizing silicon liquid produced during the melting of the partial gallium-doped silicon material, so as to finally generate crystalline silicon ingots. According to the preparation method, the gallium-doped silicon materials are laid at the bottom of the crucible, so that gallium can be continuously dispersed into crystals at the bottom of the crucible in a bottom crystallization process, the bottom doping concentration of the silicon ingots is improved, the bottom resistance of the silicon ingots can be effectively controlled, the distribution range of the resistivity of the silicon ingots in the vertical direction is reduced, and the proportion of the qualified silicon ingots with the resistivity of 0.8-3 omega.cm is increased. Besides, the invention further discloses the gallium-doped crystalline silicon prepared by virtue of the preparation method.

Description

technical field [0001] The invention relates to the field of preparation of solar photovoltaic materials, in particular to a preparation method of gallium-doped crystalline silicon with uniform resistivity distribution. Background technique [0002] At present, cast polycrystalline silicon wafers are mainly P-type polycrystalline, and the dopant is mainly boron. Because the segregation coefficient of boron is close to 1, the resistivity distribution is relatively uniform, and the recycled material is easy to handle and use. However, due to the presence of boron-oxygen complexes in boron-doped silicon wafers, light-induced attenuation will occur in the subsequent use of the solar cells. [0003] For P-type silicon wafers, gallium-doped silicon wafers have been proven to have no light attenuation, but because the segregation coefficient of gallium in silicon is extremely low, only 0.008, the resistivity distribution of normal gallium-doped silicon ingots in actual production i...

Claims

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Application Information

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IPC IPC(8): C30B29/06C30B28/06C30B11/00
Inventor 张帅朱常任郭晓琛王双丽
Owner JIANGSU XIEXIN SILICON MATERIAL TECH DEV
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