Method for manufacturing substrate for solar cell and substrate for solar cell

A solar cell comprising

• a CZ silicon single crystal substrate doped with a p type dopant or an n type dopant and containing 12 ppm or more oxygen atoms and provided with texture formed on a light-receiving surface of the silicon single crystal substrate to reduce reflectance of light of the light-receiving surface of the silicon single crystal substrate,
• a light-receiving surface electrode formed on the light-receiving surface of the silicon single crystal substrate, and
• a back surface electrode formed on a backside of the silicon single crystal substrate,
• wherein in the silicon single crystal substrate provided with the texture, oxide precipitate nuclei are previously dissolved completely and a solid solution containing oxygen atoms is formed uniformly throughout the substrate, wherein the silicon single crystal substrate is free from spiral oxygen-induced defects that are observed as a spiral pattern in an EL (electroluminescence) image in the solar cell after fabrication of the solar cell, and
• wherein a conversion efficiency of the solar cell is about 20% and variation thereof is about 0.1%.

A solar cell comprising

• a CZ silicon single crystal substrate doped with a p-type dopant or an n-type dopant and containing 12 ppm or more oxygen atoms and provided with texture formed on a light-receiving surface of the silicon single crystal substrate to reduce reflectance of light of the light-receiving surface of the silicon single crystal substrate,
• a light-receiving surface electrode formed on the light-receiving surface of the silicon single crystal substrate, and
• a backside surface electrode formed on a backside of the silicon single crystal substrate,
• the silicon single crystal substrate having an emitter layer in the light-receiving surface, and a BSF layer and an aluminum oxide passivation film in the backside of the silicon single crystal substrate,
• wherein in the silicon single crystal substrate provided with the texture, oxide precipitate nuclei are previously dissolved and a solid solution containing oxygen atoms is formed uniformly throughout the substrate, and wherein the silicon single crystal substrate is free from an oxygen-induced defect that is observed as a spiral pattern in an EL (electroluminescence) image in the solar cell after fabrication, and a conversion efficiency of the solar cell is about 20% and variation thereof is about 0.1%.

A solar cell comprising

• a CZ silicon single crystal substrate doped with phosphor, boron, or gallium and containing 12 ppm or more oxygen atoms and provided with texture formed on a light-receiving surface of the silicon single crystal substrate to reduce reflectance of light of the light-receiving surface of the silicon single crystal substrate,
• a light-receiving surface electrode formed on the light-receiving surface of the silicon single crystal substrate, and
• a backside surface electrode formed on a backside of the silicon single crystal substrate,
• the silicon single crystal substrate having an emitter layer in the light-receiving surface,
• wherein the silicon single crystal substrate is subjected to a high temperature heat treatment at 1200° C. or higher for 5 minutes to 30 minutes in a POCl3 or nitrogen atmosphere, prior to a low temperature heat treatment at a temperature between 800° C. and 1200° C., such that oxide precipitate nuclei are previously dissolved and a solid solution containing oxygen atoms is formed in the silicon single crystal substrate, wherein the silicon single crystal substrate is free from an oxygen-induced defect that is observed as a spiral pattern in an EL (electroluminescence) image in the solar cell after fabrication, and wherein a conversion efficiency of the solar cell is about 20% and variation thereof is about 0.1%.