Lightly-doped substrate, substrate with selective emitter, and solar cell and preparation method and application thereof

Abstract

The invention provides a lightly-doped substrate, a substrate with a selective emitter, and a solar cell and a preparation method and application thereof. The lightly-doped substrate comprises a P type silicon wafer layer, an N type silicon layer, a first phosphorosilicate glass layer, an oxide layer and a second phosphorosilicate glass layer which are connected in sequence. According to the invention, in the subsequent heavy doping process of the lightly-doped substrate, the doping uniformity of a doping source on the surface of a silicon wafer can be improved, and the square resistance valueof a heavy doped region can be reduced, so that the silver-silicon contact resistance is reduced; the preparation method of the lightly-doped substrate is simple, easy to implement and suitable for industrial large-scale production and application; and the phosphorus content of the heavily-doped region in the substrate with the selective emitter prepared by the lightly-doped substrate is relatively high, the sheet resistance of the heavily doped region is relatively low and uniform, and the prepared solar cell has relatively high light conversion efficiency.

Description

technical field [0001] The invention belongs to the field of solar cells, and relates to a lightly doped substrate, a substrate with a selective emitter, a solar cell and a preparation method and application thereof. Background technique [0002] Laser Doped Selective Emitter (LDSE) uses a laser beam to selectively irradiate the silicon surface to make the silicon substrate into a molten state, and the dopant atoms can quickly enter the molten silicon. When the laser beam disappears, the molten silicon After cooling and crystallization, the dopant atoms enter the silicon crystal to form a heavily doped region. [0003] Before LDSE doping, the first diffusion is carried out, and the diffused phosphosilicate glass layer is the source of LDSE doping source. At present, in order to ensure the efficiency of the battery, the square resistance of the first diffusion is relatively high, the thickness of the phosphosilicate glass layer is relatively low, and the phosphorus content i...

AI Technical Summary

Problems solved by technology

In the process of leading to LDSE, the doped area is prone to uneven square resistance, and the doped square resistance cannot be very low

[0004] CN107394012A discloses a silicon wafer laser-doped SE diffusion process, said process is to form a diffused first layer of phosphorus layer and a diffused second phosphorus layer on the surface of a silicon wafer, increase the deposition process of a phosphorus-attached layer and the silicon surface after diffusion Phosphorus-attached layer is formed, which not only solves the problem of insufficient PSG concentration after laser ablation, but also easily removes the phosphorous-attached layer in the subsequent phosphorus washing process, which can effectively solve the problem caused by low PSG concentration during laser doping. The problem of poor ohmic contact and low filling factor, but the energy during laser doping is high, and there is no oxide layer and buffer layer in the middle, which will lead to uneven doping resistance

And the diffusion of the second phosphorus layer may damage the doped phosphorus layer in subsequent processing, thereby affecting the uniformity of the square resistance of the doped region

[0005] CN106206847A discloses a kind of ultra-low concentration POCl based on low pressure diffusion furnace 3 The high-temperature diffusion method includes the following steps: (1) entering the boat; (2) phosphorus deposition; (3) heating up to push the junction; (4) cooling down and oxidizing; (5) leaving the boat; , High-temperature distributed anaerobic propulsion mode, realizing ultra-low POCl 3 Concentration of phosphorus diffusion, POCl 3 The concentration is only 10% of the conventional process. This diffusion method can significantly increase the open circuit voltage of the cell and reduce the amount of carrier gas, thereby ensuring the uniformity and stability of the square resistance. However, the uniformity and stability of the square resistance still need to be improved.

The low-temperature, low-surface-concentration, and high-resistance diffusion process described in this invention reduces the reaction temperature in the deposition and diffusion steps compared with the traditional process, thereby reducing the surface recombination rate, and at the same time, the lower diffusion temperature in the polysilicon diffusion process makes impurities more It is beneficial to migrate towards the gettering point, thereby improving the battery efficiency, but its battery efficiency still needs to be improved

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