Preparation method of gallium-doped polycrystalline silicon film, and application of gallium-doped polycrystalline silicon film in solar cells

Abstract

The invention discloses a preparation method of a gallium-doped polycrystalline silicon film. The preparation method comprises the following steps: preparing a dielectric layer material on the surfaceof a cleaned silicon wafer; further depositing an intrinsic silicon film layer; then depositing a layer of a gallium-containing compound on the surface of the intrinsic silicon film by using a physical deposition method, wherein the intrinsic silicon layer and the gallium-containing compound can be repeatedly and alternately deposited; and carrying out high-temperature annealing at a temperatureof 800 DEG C or above in a protective atmosphere. According to the invention, the passivation quality of a p type silicon oxide / polycrystalline silicon passivation contact technology is effectively improved, and J0 and s can be reduced to below 10 fA / cm<2>; gallium source materials are rich and wide in source; the required equipment is simple, the treatment method is diversified, the repeatabilityis strong, and the process window is large; the p type silicon oxide / polycrystalline silicon passivation contact is simple in structure, reliable in performance and completely suitable for back passivation of a silicon oxide / polycrystalline silicon passivation contact battery; and the technical cost is relatively low, and the practicability is relatively high.

Description

technical field [0001] The invention relates to the field of solar cell components, in particular to the preparation of polysilicon thin films. Background technique [0002] The tunneling oxygen passivated emitter solar cell (TOPCon) is a new type of silicon solar cell proposed by the Fraunhofer Institute in Germany in 2013 (see the attached figure 1 ), is a battery device that achieves full-area high-efficiency passivation and carrier collection by silicon oxide and doped polysilicon. At present, it can be divided into two categories: p-type TOPCon (boron-doped polysilicon and silicon oxide layer) that collects holes and n-type TOPCon (phosphorus-doped polysilicon and silicon oxide layer) that collects electrons. On n-type silicon wafers, n-type TOPCon has an excellent passivation level, and the key indicator of passivation quality - single-sided saturated dark field current (J 0,s ) can easily achieve 10fA / cm 2 Below; while the passivation quality of p-type TOPCon is us...

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Problems solved by technology

[0005] (2) Boron in SiO 2 layer has low diffusivity, and in SiO 2 It is easy to accumulate in the layer, making the overall passivation effect poor;

[0006] (3) The diffusion rate of boron in silicon is high, and it will quickly diffuse into the silicon wafer in large quantities under high-temperature annealing, thereby forming a higher Auger recombination and reducing the carrier lifetime;

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