Patent US5544773A successfully refreshed from Google Patents.
US4056879A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of forming silicon solar energy cell having improved back contact
Assignee: BP Solar International LLC
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Filing: 1976-07-14
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Granted: 1977-11-08
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Expires: 1996-07-14
Abstract
Abstract A silicon solar energy cell having a diffusant junction extending inwardly from one surface, an aluminum-silicon junction of the opposite polarity extending inwardly from the other surface, and a film of aluminum-oxygen-diffusant formed over the aluminum-silicon junction. The structure is formed by diffusing an unprotected wafer, coating the diffusant glass so formed on one side of the wafer with aluminum, and heating the wafer.
Inventors
- 👤 Joseph Lindmayer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:20
CPC Classifications
H; H10; H10F; H10F10/00; H10F10/10; H10F10/14; H10F71/00; H10F71/121; Y; Y02; Y02E; Y02E10/00; Y02E10/50; Y02E10/547; Y02P; Y02P70/00; Y02P70/50; Y10; Y10S; Y10S148/00; Y10S148/015; Y10S148/018; Y10S148/02; Y10S148/033; Y10S148/12; Y10S148/151; Y10S148/153; Y10S438/00; Y10S438/914; Y10S438/923
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
138 words
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.
Claim 2
Independent Claim
138 words
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.
Claim 3
Dependent Claim
31 words
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° and 900° C.
Claim 4
Dependent Claim
23 words
A method as claimed in claim 2, in which said heating is carried out at a range of about 820° to 860° C.
Claim 5
Dependent Claim
28 words
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° C.
Claim 6
Dependent Claim
37 words
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.
Claim 7
Dependent Claim
16 words
A method as claimed in claim 1, in which the aluminum coating is applied by evaporation.
Claim 8
Dependent Claim
20 words
A method as claimed in claim 6, in which the aluminum coating is applied to a thickness of about 5000A.
Claim 9
Dependent Claim
18 words
A method as claimed in claim 5, in which said electrically conductive metal is titanium-gold, titanium-silver or chromium.
Claim 10
Dependent Claim
22 words
A method as claimed in claim 1, in which said wafer is heated with said diffusant in an atmosphere that contains argon.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-11-07 | 1981-05-09 | 1981-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-11-07 | 1985-05-09 | 1985-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-11-07 | 1989-05-09 | 1989-11-08 | $7700.00 | Window Closed / Lapsed |