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Vapor deposition method of forming low cost semiconductor solar cells including reconstitution of the reacted gases

  • US 3,969,163 A
  • Filed: 09/19/1974
  • Issued: 07/13/1976
  • Est. Priority Date: 09/19/1974
  • Status: Expired due to Term
First Claim
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1. A method of forming semiconductor grade silicon from lower grade silicon, which comprises the steps of:

  • a. providing a first chamber having at least a zone thereof maintained at a temperature below about 700°

    C,b. passing a graphite fiber substrate through said zone,c. passing a gaseous mixture of silicon difluoride and a suitable dopant into said first chamber including said zone whereby said silicon difluoride decomposes to pure silicon which deposits on said substrate and gaseous silicon tetrafluoride,d. removing said silicon tetrafluoride from said first chamber,e. providing a second chamber containing impure silicon,f. heating said chamber to a temperature in the range of 750°

    to about 1200°

    C, andg. passing silicon tetrafluoride, including at least a portion of the silicon tetrafluoride removed from said first chamber, into said second chamber to form additional silicon difluoride which is then introduced into said first chamber.

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