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US 2010/0139764 A1Published application
Backside Contact Solar Cell With Formed Polysilicon Doped Regions
AssigneeSunPower Corporation
InventorDavid D. SMITH
Life of this patent
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Abstract
A solar cell includes abutting P-type and N-type doped regions in a contiguous portion of a polysilicon layer. The polysilicon layer may be formed on a thin dielectric layer, which is formed on a backside of a solar cell substrate (e.g., silicon wafer). The polysilicon layer has a relatively large average grain size to reduce or eliminate recombination in a space charge region between the P-type and N-type doped regions, thereby increasing efficiency.
Claims20
A method of fabricating a solar cell, the method comprising:
- forming a polysilicon layer over a back surface of a silicon substrate;
- forming a first dopant source and a second dopant source over the polysilicon layer;
- and
- locally heating the polysilicon layer to drive dopants from the first dopant source and the second dopant source to the polysilicon layer to form a P-type doped region and an N-type doped region in a contiguous portion of the polysilicon layer and to recrystallize the polysilicon layer to increase its average grain size.
1 more element
A solar cell comprising:
- a silicon substrate;
- a dielectric formed over a backside of the silicon substrate, the backside being opposite a front side that faces the sun during normal operation;
- and
- a polysilicon layer formed over the dielectric, the polysilicon layer having a P-type doped region and an N-type doped region formed in a contiguous portion of the polysilicon layer, the polysilicon layer having an average grain size of at least 1 micron at an interface between the P-type doped region and the N-type doped region.
1 more element
A method of fabricating a solar cell, the method comprising:
- forming a dielectric over a silicon substrate;
- forming a polysilicon layer over the dielectric;
- performing a laser annealing process to diffuse dopants into the polysilicon layer and form abutting P-type doped and N-type doped regions in the polysilicon layer.
Dependencies are inferred from the claim text.