Pre-diffusion film for passivating contact structure and its preparation method and application

Abstract

The invention provides a pre-diffusion sheet for a passivation contact structure. The pre-diffusion sheet comprises a passivation contact matrix and a doping pre-diffusion layer, wherein the doping pre-diffusion layer is combined with a surface of the passivation contact matrix, a part of doing substance of the doping pre-diffusion layer is diffused and enters different depths in the surface of the passivation contact matrix, and the square resistance of the passivation contact structure with the doping pre-diffusion layer is larger than 90 ohms per square. By pre-diffusion, certain surface doping is formed on the surface of the passivation contact matrix, an energy band is bent on the surface to a certain extent, the carrier selectivity and the transmission capability are improved, the contact resistance is reduced, the thickness requirement of tunneling amorphous silicon, tunneling silicon oxide or other passivation tunneling layers is also reduced, meanwhile, the doping concentration dependence on doping amorphous silicon is also reduced, the excessive dependence on a work function of a new material is reduced, and the battery yield is improved.

Description

technical field [0001] The invention relates to a passivation contact interface structure, in particular to a pre-diffusion sheet that can be used in the passivation contact structure of solar cells, and to a preparation method thereof. Background technique [0002] Passivation contact is also called carrier selective collection, which is a hot research direction of silicon solar cells in recent years. The passivation contact structure can form a significant energy band bending on the silicon surface, allowing one kind of carrier to pass through while the other kind of carrier cannot pass through, forming a good carrier collection, and at the same time inhibiting the carrier from being released at the interface. compound. Therefore, the passivation contact structure can realize high-efficiency passivation and carrier collection, and eliminate the direct contact between silicon and metal, thereby improving the passivation effect and enabling the solar cell to obtain a high o...

AI Technical Summary

Problems solved by technology

[0008] The disadvantages of the tunneling oxygen passivation contact structure (TOPCon) are: during the high-temperature annealing process, if the process is not properly controlled, impurities 10 doped with polysilicon will enter the silicon oxide layer in large quantities, thereby destroying the silicon oxide layer and reducing the interface passivation effect; metal sintering When the slurry burns through the polysilicon layer, it directly contacts the silicon surface, which significantly increases the surface recombination rate

[0009] The disadvantage of silicon heterojunction (SHJ) is that it requires extremely high quality and thickness of intrinsic amorphous silicon

[0010] The disadvantage of the non-doped heterojunction (DASH) structure is: similar to the silicon heterojunction, the structure requires extremely high quality and thickness of intrinsic amorphous silicon

The thickness of intrinsic amorphous silicon needs to be strictly controlled at about 5-6nm. A lower thickness will affect the passivation effect, and a higher thickness will affect the carrier transport capacity.

Strict requirements for intrinsic silicon thin films have become the main reason for limiting the improvement of battery yield

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