DOPING PATTERN FOR POINT CONTACT SOLAR CELLS

• US 20130291932A1
• Filed: 05/04/2012
• Published: 11/07/2013
• Est. Priority Date: 05/04/2012
• Status: Active Grant

• Current Assignee: Varian Semiconductor Equipment Associates Incorporated (Applied Materials Incorporated)
• Original Assignee: Varian Semiconductor Equipment Associates Incorporated (Applied Materials Incorporated)
• Inventors: Bateman, Nicholas, Graff, John
• Granted Patent: US 8,993,373 B2
• Time in Patent Office: Days
• US Class Current: 136/255
• CPC Class Codes: H01L 31/0682 back-junction, i.e. rearside emitter, solar cells, e.g. interdigitated base-emitter regions back-junction 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

Methods of doping a solar cell, particularly a point contact solar cell, are disclosed. One surface of a solar cell may require portions to be n-doped, while other portions are p-doped. At least one lithography step can be eliminated by the use of a blanket doping of species having one conductivity and a patterned counterdoping process of species having the opposite conductivity. The areas doped during the patterned implant receive a sufficient dose so as to completely reverse the effect of the blanket doping and achieve a conductivity that is opposite the blanket doping. In some embodiments, counterdoped lines are also used to reduce lateral series resistance of the majority carriers.

Claims

1. A method of creating a point contact solar cell, comprising:

providing a substrate having a first conductivity;

performing a blanket implant on a surface of said substrate with a species of a second conductivity, said second conductivity being opposite said first conductivity, so as to create a base of said first conductivity and an emitter of said second conductivity;

performing a patterned implant of said surface of said substrate using a species of said first conductivity to create discrete counterdoped regions of said first conductivity on said surface, wherein said counterdoped regions are electrically connected to said base; and

performing a second patterned implant of said surface of said substrate using a species of said second conductivity to create highly doped emitter regions.

2. The method of claim 1, wherein said counterdoped regions are circular or rectangular.

3. The method of claim 1, further comprising affixing metal contacts to said counterdoped regions and said highly doped emitter regions.

4. The method of claim 1, further comprising performing a patterned implant on said surface of said substrate with a species of said first conductivity so as to create lines connecting said discrete counterdoped regions.

5. The method of claim 4, wherein said lines are in one direction.

6. The method of claim 4, wherein said lines are in two perpendicular directions, thereby creating a grid pattern.

7. The method of claim 4, further comprising affixing metal contacts to said counterdoped regions and said highly doped emitter regions.

8. A point contact solar cell, comprising:

an illuminated surface;

a non-illuminated surface;

a n-type base located between said illuminated surface and said non-illuminated surface;

wherein said non-illuminated surface is p-doped to form an emitter and comprises;

a plurality of discrete counterdoped n-type regions in electrical contact with said base; and

a plurality of counterdoped n-type lines connecting said discrete counterdoped n-type regions.

9. The point contact solar cell of claim 8, wherein said discrete counterdoped n-type regions are circular or rectangular.

10. The point contact solar cell of claim 8, wherein said non-illuminated surface further comprises a plurality of discrete heavily doped emitter regions.

11. The point contact solar cell of claim 8, wherein said lines are in one direction.

12. The point contact solar cell of claim 8, wherein said lines are in two perpendicular directions, thereby creating a grid pattern.

13. A method of creating a point contact solar cell, comprising:

providing a substrate having a first conductivity;

performing a blanket implant on a surface of said substrate with a species of a second conductivity, said second conductivity being opposite said first conductivity, so as to create a base of said first conductivity and an emitter of said second conductivity;

performing a patterned implant of said surface of said substrate using a species of said first conductivity so as to counterdope regions on said surface so as to create discrete counterdoped dots of said first conductivity on said surface, wherein said counterdoped dots are electrically connected to said base.

14. The method of claim 13, further comprising performing a patterned implant on said surface of said substrate with a species of said first conductivity so as to create lines connecting said discrete counterdoped dots.

15. The method of claim 14, wherein said lines are in one direction.

16. The method of claim 14, wherein said lines are in two perpendicular directions, thereby creating a grid pattern.

17. The method of claim 13, wherein said dots are circular or rectangular.

18. The method of claim 13, further comprising affixing metal contacts to said counterdoped dots.