Manufacture of semiconductor ribbon and solar cells

• US 4,095,329 A
• Filed: 12/05/1975
• Issued: 06/20/1978
• Est. Priority Date: 12/05/1975
• Status: Expired due to Term

• Current Assignee: ASE Americas Incorporated
• Original Assignee: Mobil Tyco Solar Energy Corporation
• Inventors: Ravi, Kramadhati Venkata
• Primary Examiner(s): Tupman, W.
• Application Number:
  US05/638,186
• Time in Patent Office: 928 Days
• Field of Search: 29/572, 29/580, 29/578, 156/619, 23/273 SP
• US Class Current: 438/68
• CPC Class Codes: C30B 33/00 After-treatment of single crystals or homogeneous polycrystalline material with defined structure C30B31/00 takes precedence
• CPC Class Codes: H01L 31/035281 Shape of the body
• CPC Class Codes: H01L 31/068 the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
• CPC Class Codes: H01L 31/1804 comprising only elements of Group IV of the Periodic Table
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A method is provided for producing solar cells employing slightly curved or nearly flat monocrystalline silicon ribbons. The ribbons are formed by cutting or slicing monocrystalline hollow tubes along their lengths, the tubes having been formed according to crystal growing processes disclosed in U.S. Pat. No. 3,591,348.

Claims

1. A method of producing ribbon-like substantially monocrystalline bodies for use in fabricating solar cells comprising the steps of:

(a) providing a tubular substantially monocrystalline body of a semiconductor material;

(b) forming a photovoltaic junction in the tubular body; and

then

(c) dividing said tubular body lengthwise into a plurality of ribbon-like bodies.

2. Method according to claim 1 wherein said tubular body has a substantially circular cross-section.

3. Method according to claim 1 wherein said photovoltaic junction is formed by diffusing a dopant into the tubular body.

4. Method according to claim 1 wherein the photovoltaic junction is formed in the tubular body by ion-implantation.

5. Method according to claim 1 wherein said monocrystalline hollow body is divided by dissolving selected portions thereof with a liquid solvent.

6. Method according to claim 5 including the step of coating selected areas of the tubular body with a material that is resistant to said solvent, so that said predetermined areas are protected against dissolution by the solvent.

7. Method according to claim 1 including the steps of forming a protective film on the surfaces of the tubular hollow body, and removing selected portions of said protective film, and dividing said tubular body into a plurality of ribbon-like bodies by etching said tubular body where the selected portions of the protective film were removed.

8. Process according to claim 7 wherein said protective film comprises a wax, and said lined portions are removed by scribing.

9. Method of forming solar cells comprising the steps of:

(a) producing a tubular substantially monocrystalline body of a selected semiconductor material,

(b) forming a photovoltaic junction near the outer surface of said tubular body;

(c) dividing said tubular body longitudinally into a plurality of elongate bodies each having first and second surfaces which constitute parts of the outer and inner surfaces respectively of said tubular body, and a photovoltaic junction near said first surface; and

(d) forming electrodes on said first and second surfaces.

10. Method of claim 9 wherein said tubular body has an oxide layer at its outer and inner surfaces after said junction is formed, and further including the step of removing each oxide layer before formation of the electrodes.

11. Method of claim 10 wherein said tubular body is divided by etching away selected longitudinally extending areas thereof.

12. Method of claim 11 wherein the division of the tubular body comprises the steps of coating the tubular body with a photoresist, removing the photoresist from said selected areas, and contacting said tubular body with an etchant which is capable of dissolving said tubular body and is inert with respect to said photoresist.