High-Efficiency Thin-Film Solar Cells

• US 20100175752A1
• Filed: 11/13/2009
• Published: 07/15/2010
• Est. Priority Date: 11/13/2008
• Status: Active Grant

• Current Assignee: Ob Realty, LLC
• Original Assignee: Solexel, Inc.
• Inventors: Moslehi, Mehrdad M., Wang, David Xuan-Qi
• Granted Patent: US 8,294,026 B2
• Time in Patent Office: Days
• US Class Current: 136/256
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 29/045 by their particular orientation of crystalline planes
• CPC Class Codes: H01L 29/0657 characterised by the shape of the body
• CPC Class Codes: H01L 31/022425 for solar cells
• CPC Class Codes: H01L 31/0236 Special surface textures
• CPC Class Codes: H01L 31/02363 of the semiconductor body itself, e.g. textured active layers
• CPC Class Codes: H01L 31/035281 Shape of the body
• CPC Class Codes: H01L 31/056 the light-reflecting means being of the back surface reflector [BSR] type
• 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: H01L 31/182 Special manufacturing methods for polycrystalline Si, e.g. Si ribbon, poly Si ingots, thin films of polycrystalline Si
• CPC Class Codes: H01L 31/1892 methods involving the use of temporary, removable substrates
• CPC Class Codes: Y02E 10/52 PV systems with concentrators
• CPC Class Codes: Y02E 10/546 Polycrystalline silicon PV cells
• 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
• CPC Class Codes: Y10T 117/1092 Shape defined by a solid member other than seed or product [e.g., Bridgman-Stockbarger]

Abstract

A three-dimensional solar cell comprising a semiconductor substrate with an inverted pyramidal cavity, emitter metallization regions on ridges on the surface of the semiconductor substrate which define an opening of the inverted pyramidal cavity, and base metallization regions on a region which form the apex of the inverted pyramidal cavity. A method for fabricating a three-dimensional thin-film solar cell from an inverted pyramidal three-dimensional thin-film silicon substrate by doping ridges on the surface of the semiconductor substrate which define an opening of an inverted pyramidal cavity on the substrate to form an emitter region, and doping a region which forms the apex of the inverted pyramidal cavity to form a base region. Adding a surface passivation layer to the surface of the substrate. Selectively etching the passivation layer from the emitter region and base region. Then concurrently metallizing the emitter region and base region.

Claims

1. A three-dimensional solar cell, comprising:

a plurality of ridges on the surface of a semiconductor substrate defining an opening of an inverted pyramidal cavity;

a plurality of walls defining said inverted pyramidal cavity;

emitter metallization regions on said ridges forming the opening of said inverted pyramidal cavity; and

base metallization regions on a region forming an apex of said inverted pyramidal cavity.

2. The solar cell of claim 1, wherein said semiconductor substrate is a mono-crystalline silicon substrate.

3. The solar cell of claim 1, wherein said base metallization regions are mounted on a metal surface of a carrier plate to form base interconnects.

4. The solar cell of claim 1, wherein a diagonal dimension defining said base opening of said inverted pyramidal cavity is in the range of 1 um to 1 mm.

5. The solar cell of claim 1, wherein said semiconductor substrate comprises a plurality of said inverted pyramidal cavities.

6. The solar cell of claim 5, wherein said plurality of said inverted pyramidal cavities have a plurality of pyramidal shapes.

7. The solar cell of claim 5, wherein said plurality of said inverted pyramidal cavities have a plurality of pyramidal sizes.

8. The solar cell of claim 5, wherein said ridges forming the opening of each of said inverted pyramidal cavities have a width ranging from 10 um to 100 um.

9. The solar cell of claim 5, wherein said apex of said inverted pyramidal cavities further is substantially planar.

10. The solar cell of claim 5, wherein said plurality of said inverted pyramidal cavities are arranged in arrays on the silicon substrate.

11. The solar cell of claim 5, wherein said plurality of said inverted pyramidal cavities are arranged in a staggered pattern on the silicon substrate.

12. The solar cell of claim 5, wherein said plurality of said inverted pyramidal cavities comprise:

a first plurality of inverted pyramidal cavities; and

a second plurality of inverted pyramidal cavities,

wherein a diagonal dimension defining said base opening of said second plurality of inverted pyramidal cavities is smaller than a diagonal dimension defining said base opening of said first plurality of inverted pyramidal cavities.

13. The solar cell of claim 12, wherein said plurality of said inverted pyramidal cavities are arranged in a staggered pattern on the silicon substrate.

14. The solar cell of claim 12, wherein said apex of said inverted pyramidal cavities of said first plurality of inverted pyramidal cavities is substantially planar.

15. A method for fabrication of a three-dimensional thin-film solar cell from an inverted pyramidal three-dimensional thin-film silicon substrate, the method comprising:

doping ridges forming an opening of an inverted pyramidal cavity on a first side of said silicon substrate with a n-type dopant to form an emitter region;

doping a region forming an apex of said inverted pyramidal cavity on a second side of said silicon substrate with a p-type dopant to form a base region;

adding a surface passivation layer to said first side and said second side of said silicon substrate;

selectively etching said passivation layer on said emitter region and said base region to form contact openings; and

concurrently metallizing said emitter region and said base region.

16. The method of claim 15, wherein said step of doping ridges forming an opening of an inverted pyramidal cavity further comprises:

selectively coating ridges forming an opening of an inverted pyramidal cavity on a first side of said silicon substrate with a n-type dopant; and

forming an emitter region on said ridges forming an opening according to a thermal annealing process.

17. The method of claim 15, wherein said step of doping a region forming an apex of said inverted pyramidal cavity further comprises:

selectively coating a region forming an apex of said inverted pyramidal cavity on a second side of said silicon substrate with a p-type dopant; and

forming a base region on said region forming an apex according to a thermal annealing process.

18. The method of claim 15, wherein said step of adding a surface passivation layer to said first side and said second side of said silicon substrate comprises adding a thermally grown silicon dioxide.

19. The method of claim 15, further comprising the step of mounting said base region onto a metal surface of a carrier plate to form metal base interconnects.

20. A method for fabrication of a three-dimensional thin-film solar cell from an inverted pyramidal three-dimensional thin-film silicon substrate, the method comprising:

doping ridges forming an opening of an inverted pyramidal cavity on a first side of said silicon substrate with a p-type dopant to form a base region;

doping a region forming an apex of said inverted pyramidal cavity on a second side of said silicon substrate with a n-type dopant to form an emitter region;

adding a surface passivation layer to said first side and said second side of said silicon substrate;

selectively etching said passivation layer on said emitter region and said base region to form contact openings; and

concurrently metallizing said emitter region and said base region.