COUNTERDOPING FOR SOLAR CELLS
Methods of counterdoping a solar cell, particularly an IBC solar cell are disclosed. One surface of a solar cell may require portions to be n-doped, while other portions are p-doped. Traditionally, a plurality of lithography and doping steps are required to achieve this desired configuration. In contrast, one lithography step can be eliminated by the use of a blanket doping of one conductivity and a mask patterned counterdoping process of the opposite conductivity. The areas dosed during the masked patterned doping 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 another embodiment, the counterdoping is performed by means of a direct patterning technique, thereby eliminating the remaining lithography step. Various methods of direct counterdoping processes are disclosed.
1 . A solar cell comprising:
a substrate having an illuminated surface and a non-illuminated surface, wherein light impinges said illuminated surface;
an anti-reflective coating on said illuminated surface of said substrate;
a front surface field under said anti-reflective coating;
a plurality of n-type doped regions on said non-illuminated surface having an n-type dopant concentration;
a plurality of p-type doped regions on said non-illuminated surface having a p-type dopant concentration and said n-type dopant concentration, wherein said p-type dopant concentration is larger than said n-type dopant concentration; and
a plurality of contacts disposed on said plurality of p-type doped regions and said plurality of n-type doped regions.
2 . The solar cell of claim 1 , wherein one of said plurality of p-type doped regions is disposed between two of said plurality of n-type doped regions.
3 . The solar cell of claim 1 , wherein said plurality of p-type doped regions and said plurality of n-type doped regions alternate across said non-illuminated surface.
4 . The solar cell of claim 1 , further comprising a passivation layer on said non-illuminated surface.
5 . The solar cell of claim 1 , wherein said plurality of p-type regions extends deeper into said substrate than said plurality of n-type doped regions.
6 . A solar cell comprising:
a substrate having an illuminated surface and a non-illuminated surface, wherein light impinges said illuminated surface;
an anti-reflective coating on said illuminated surface of said substrate;
a front surface field under said anti-reflective coating;
a plurality of p-type doped regions on said non-illuminated surface having a p-type dopant concentration;
a plurality of n-type doped regions on said non-illuminated surface having an n-type dopant concentration and said p-type dopant concentration, wherein said n-type dopant concentration is larger than said p-type dopant concentration; and
a plurality of contacts disposed on said plurality of p-type doped regions and said plurality of n-type doped regions.
7 . The solar cell of claim 6 , wherein one of said plurality of p-type doped regions is disposed between two of said plurality of n-type doped regions.
8 . The solar cell of claim 6 , wherein said plurality of p-type doped regions and said plurality of n-type doped regions alternate across said non-illuminated surface.
9 . The solar cell of claim 6 , further comprising a passivation layer on said non-illuminated surface.
10 . The solar cell of claim 6 , wherein said plurality of n-type regions extends deeper into said substrate than said plurality of p-type doped regions.
11 . A solar cell comprising:
a substrate having an illuminated surface and a non-illuminated surface, wherein light impinges said illuminated surface;
a plurality of first doped regions on said non-illuminated surface having a first dopant concentration of a first dopant type;
a plurality of second doped regions on said non-illuminated surface having said first dopant concentration and a second dopant concentration of a second dopant type, said second dopant concentration being larger than said first dopant concentration; and
a plurality of contacts disposed on said plurality of first doped regions and said plurality of second doped regions.
12 . The solar cell of claim 11 , wherein one of said plurality of second doped regions is disposed between two of said plurality of first doped regions.
13 . The solar cell of claim 11 , wherein said plurality of first doped regions and said plurality of second doped regions alternate across said non-illuminated surface.
14 . The solar cell of claim 11 , further comprising an anti-reflective coating on said illuminated surface.
15 . The solar cell of claim 14 , further comprising a front surface field under said anti-reflective coating.
16 . The solar cell of claim 11 , wherein said first dopant type is p-type and said second dopant type is n-type.
17 . The solar cell of claim 11 , wherein said first dopant type is n-type and said second dopant type is p-type.
18 . The solar cell of claim 11 , further comprising a passivation layer on said non-illuminated surface.
19 . The solar cell of claim 11 , wherein said plurality of second doped regions extends deeper into said substrate than said plurality of first doped regions.