Claims
- 1. A method of forming a silicon solar energy cell having junctions of opposite polarities, comprising heating a crystalline silicon wafer with a diffusant to form a front junction in a zone extending inwardly from the front surface of the wafer, a back junction extending inwardly from the back surface of the wafer and films of diffusant glass on said front and back surfaces, applying a coating of aluminum to the diffusant glass on the back surface of the wafer, and heating the wafer at a sufficient temperature until the aluminum has negated the polarity of the back junction and formed an aluminum-silicon junction in its place, said aluminum-silicon junction having a polarity of opposite sign to the polarity of the front junction, and until the glass film on the back surface of the wafer has become electrically conductive.
- 2. A method as claimed in claim 1, in which said diffusant is phosphorus and the heating with the phosphorus is carried out at a range of about 750.degree. and 900.degree. C.
- 3. A method as claimed in claim 2, in which said heating is carried out at a range of about 820.degree. to 860.degree. C.
- 4. A method as claimed in claim 1, in which said heating after application of a coating of aluminum has been applied is carried out at about 800.degree. C.
- 5. A method as claimed in claim 1, in which a coating of electrically conductive metal is thereafter applied to the film on the back surface of the wafer to form an additional back contact for said wafer.
- 6. A method as claimed in claim 1, in which the aluminum coating is applied by evaporation.
- 7. A method as claimed in claim 6, in which the aluminum coating is applied to a thickness of about 5000A.
- 8. A method as claimed in claim 5, in which said electrically conductive metal is titanium-gold, titanium-silver or chromium.
- 9. A method as claimed in claim 1, in which said wafer is heated with said diffusant in an atmosphere that contains argon.
Parent Case Info
This is a division of application Ser. No. 614,619, filed Sept. 18, 1975, now U.S. Pat. No. 3,990,097.
US Referenced Citations (5)
Divisions (1)
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Number |
Date |
Country |
Parent |
614619 |
Sep 1975 |
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