Method for manufacturing a FZ silicon single crystal subject to additional gallium doping for solar cells

Patent metadata

Field	Value
Publication number	US-10487417-B2
Application number	US-201515538103-A
Country	US
Kind code	B2
Filing date	Nov 26, 2015
Priority date	Jan 6, 2015
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

The present invention is a method for manufacturing an FZ silicon single crystal for a solar cell, including the steps of: pulling a CZ silicon single crystal doped with gallium by a Czochralski method; and float-zone processing a raw material rod, with the raw material rod being the CZ silicon single crystal, at 1.6 atmospheric pressure or more to manufacture the FZ silicon single crystal. As a result, it is possible to provide a method for manufacturing an FZ silicon single crystal for a solar cell that can decrease the amount of gallium dopant evaporated during the float-zone processing, thereby preventing the silicon single crystal from increasing the resistance while decreasing oxygen, which is inevitably introduced into a CZ crystal, and preventing formation of a B-O pair, which causes a problem to the characteristics of a solar cell.

First claim

The invention claimed is:

1. A method for manufacturing an FZ silicon single crystal for a solar cell, comprising the steps of:
pulling a CZ silicon single crystal doped with gallium by a Czochralski method; and
float-zone processing a raw material rod, with the raw material rod being the CZ silicon single crystal, at 1.6 atmospheric pressure or more to manufacture the FZ silicon single crystal; wherein
the FZ silicon single crystal is subjected to additional gallium-doping by using dopant gas in the float-zone processing, and
as the dopant gas, any of an organic gallium compound and a halogenated gallium compound is used.

2. The method for manufacturing an FZ silicon single crystal for a solar cell according to claim 1 , wherein the additional gallium-doping is performed with a flow rate and/or a concentration of the dopant gas being changed in an axial direction in accordance with an axial distribution of a gallium concentration of the CZ silicon single crystal to equalize an axial distribution of a gallium concentration of the FZ silicon single crystal.

3. The method for manufacturing an FZ silicon single crystal for a solar cell according to claim 1 , wherein the float-zone processing is performed in an atmosphere containing argon or helium.

4. The method for manufacturing an FZ silicon single crystal for a solar cell according to claim 2 , wherein the float-zone processing is performed in an atmosphere containing argon or helium.

5. The method for manufacturing an FZ silicon single crystal for a solar cell according to claim 1 , wherein the FZ silicon single crystal is manufactured to have a diameter of 150 mm or more.

6. The method for manufacturing an FZ silicon single crystal for a solar cell according to claim 2 , wherein the FZ silicon single crystal is manufactured to have a diameter of 150 mm or more.

7. The method for manufacturing an FZ silicon single crystal for a solar cell according to claim 3 , wherein the FZ silicon single crystal is manufactured to have a diameter of 150 mm or more.

8. The method for manufacturing an FZ silicon single crystal for a solar cell according to claim 4 , wherein the FZ silicon single crystal is manufactured to have a diameter of 150 mm or more.

9. A solar cell, wherein the solar cell is fabricated by using the FZ silicon single crystal manufactured by the method for manufacturing an FZ silicon single crystal for a solar cell according to claim 1 .

Assignees

• Shinetsu Chemical Co

Inventors

• Otsuka Hiroyuki

Classifications

• C30B29/06 Primary

  Silicon · CPC title

• C30B13/12 Primary

  in the gaseous or vapour state · CPC title

• C30B15/04

  adding doping materials, e.g. for n-p-junction · CPC title

• Y02E10/50

  Photovoltaic [PV] energy · CPC title

• H01L31/068

  Electricity · mapped topic