Buried-contact solar cells with self-doping contacts
A buried-contact solar cell, in-process buried-contact solar cell components and methods for making buried contact solar cells wherein a self-doping contact material is placed in a plurality of buried-contact surface grooves. By combining groove doping and metallization steps, the resulting solar cell is simpler and more economical to manufacture.
1. A method for making a solar cell, the method comprising the steps of:
scribing at least one groove in a cell substrate;
disposing a self-doping contact material within the groove; and
heating the self-doping contact material, thereby simultaneously doping and metallizing the groove.
2. The method of claim 1 wherein the self-doping contact material comprises a silicon dopant.
3. The method of claim 2 wherein the silicon dopant comprises phosphorus.
4. The method of claim 1 wherein the self-doping contact material comprises silver.
5. The method of claim 1 wherein the self-doping contact material is a paste comprising silver particles and phosphorus.
6. The method of claim 1 wherein the cell substrate comprises a p-type silicon substrate and the self-doping contact material comprises silver and a n-type silicon dopant.
7. The method of claim 1 wherein the cell substrate comprises an n-type silicon substrate and the self-doping contact material comprises silver and a p-type silicon dopant.
8. The method of claim 1 wherein the heating step further comprises alloying rear contacts on a rear surface of the cell.
9. The method of claim 8 wherein the rear contacts comprise aluminum.
10. The method of claim 1 wherein scribing at least one groove comprises scribing a plurality of grooves wherein the depth of the grooves is a multiple of the width of the grooves.
11. A solar cell, made by the method of claim 1 .
12. A substrate for making a solar cell comprising:
a planar semiconductor substrate with a front surface and a back surface, said semiconductor substrate comprising crystalline silicon;
at least one groove scribed in a surface of the semiconductor substrate; and
a self-doping contact material comprising a silicon dopant disposed within said groove, said silicon dopant comprising phosphorus.
13. The substrate of claim 12 wherein the self-doping contact material comprises a paste.
14. The substrate of claim 12 wherein the self-doping contact material comprises silver.
15. The substrate of claim 1 wherein the semiconductor substrate comprises a p-type silicon substrate and the self-doping contact material comprises silver and an n-type silicon dopant.
16. The substrate of claim 12 wherein the semiconductor substrate further comprises a phosphorus diffusion layer on the grooved surface.
17. The substrate of claim 16 further comprising an aluminum layer on the surface opposing the grooved surface.