Selective doping method for N-type solar cell

Abstract

The invention discloses a selective doping method for an N-type solar cell. The method comprises the steps of employing boron slurry as a heavily doped region diffusion source, and employing a gas-phase boron source as a lightly doped region diffusion source, before boron slurry is printed, covering the surface of a silicon wafer with a first oxide layer firstly, then covering the printed boron slurry with a second oxide layer, and through blocking of the two oxide layers, achieving the purposes that boron slurry outward expansion is reduced and the doping amount of a lightly doped region canalso be reduced, and during high-temperature propulsion, adopting a differentiated propulsion mode, firstly propelling a heavily doped region taking boron slurry as a boron source, then introducing agas-phase boron source, and jointly propelling the heavily doped region and the lightly doped region, so that heavily and lightly doped differentiated obvious distribution is realized.

Description

technical field [0001] The invention relates to the field of photovoltaics, in particular to a selective doping method for N-type solar cells. Background technique [0002] The front surface of a traditional solar cell is divided into two areas, one is the area in contact with the electrode paste, and the other is the illuminated area, that is, the area without electrode paste coverage. In the preparation of the emitter of the existing solar cell, a uniformly doped emitter is generally used, that is, the metal paste contact area and the illumination area are uniformly doped. This doping method is simple and fast, but it has disadvantages. In the metal paste contact area, we need high doping concentration to reduce the metal-semiconductor contact resistance and contact recombination; in the illuminated area, we need low doping concentration to reduce the surface R Intermittent recombination, improve carrier collection rate, improve short-wave response, and improve passivatio...

AI Technical Summary

Problems solved by technology

However, the selective doping scheme of this patent has been found to have the following problems through experiments: 1) The doping concentration in the lightly doped area is high and uneven; The difference in the diffusion depth of the impurity region is not large, and the heavily doped region has no advantage in the doping depth; the battery series resistance of this scheme will be high, the fill factor is low, and the actual efficiency gain is limited