P type gallium-doped crystalline silicon and preparation method thereof

Abstract

The invention relates to a preparation method of P type gallium-doped crystalline silicon. The preparation method comprises the following steps: feeding a silicon material containing a gallium dopant into a crucible, wherein the inner side of the sidewall of the crucible is coated with a circle of N type compensation agent doped coating and the position of the N type compensation agent doped coating is located within the range of the height difference between the silicon liquid surface after the fed silicon material containing the gallium dopant is melted and the crystal silicon formed from the silicon liquid; and melting the silicon material, and performing directional solidification so that the silicon liquid containing the gallium dopant can be formed into the P type gallium-doped crystalline silicon. According to the preparation method of the P type gallium-doped crystalline silicon, doping compensation can be realized in the crystal growth direction, and therefore, the problem of overlarge electrical resistivity distribution range of the P type gallium-doped crystalline silicon in the crystal growth direction can be solved and the electrical resistivity of the whole P type gallium-doped crystalline silicon can be accurately controlled. In addition, the invention also provides P type gallium-doped crystalline silicon produced by use of the method.

Description

technical field [0001] The invention relates to the field of preparation of solar photovoltaic materials, in particular to a P-type gallium-doped crystalline silicon and a preparation method thereof. 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 decay, but because the segregation coefficient of gallium in silicon is extremely low, only 0.008, in actual production, the resistivity distribution of silicon ingots doped with gallium in normal methods is 0.1 Be...

AI Technical Summary

Problems solved by technology

[0003] For P-type silicon wafers, gallium-doped silicon wafers have been proven to have no light decay, but because the segregation coefficient of gallium in silicon is extremely low, only 0.008, in actual production, the resistivity distribution of silicon ingots doped with gallium in normal methods is 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.

Images