Solar cells with improved lifetime, passivation and/or efficiency
A method of fabricating a solar cell can include forming a dielectric region on a silicon substrate. The method can also include forming an emitter region over the dielectric region and forming a dopant region on a surface of the silicon substrate. In an embodiment, the method can include heating the silicon substrate at a temperature above 900 degrees Celsius to getter impurities to the emitter region and drive dopants from the dopant region to a portion of the silicon substrate.
1. A solar cell, the solar cell having a front side which faces the sun during normal operation and a back side opposite the front side, the solar cell comprising:
a silicon substrate, wherein a portion of the silicon substrate has a dopant concentration of approximately less than or equal to 2×10 18 cm −3 and wherein the portion of the silicon substrate is formed at the back side of the solar cell;
a first dielectric region formed over the silicon substrate, wherein the first dielectric region is formed over the front side of solar;
a first emitter region having metal impurities formed over the first dielectric region; and
a first metal contact formed over the first emitter region.
2. The solar cell of claim 1 , wherein the portion of the silicon substrate comprises N-type dopants.
3. The solar cell of claim 1 , wherein the portion of the silicon substrate comprises phosphorus.
4. The solar cell of claim 1 , wherein the portion of the silicon substrate comprises P-type dopants.
5. The solar cell of claim 1 , wherein the portion of the silicon substrate comprises boron.
6. The solar cell of claim 1 , wherein the first emitter region comprises polysilicon.
7. The solar cell of claim 1 , further comprising:
a second emitter region having metal impurities formed over the silicon substrate, wherein the second emitter region is formed over the back side of solar; and
a second metal contact formed over the second emitter region.
8. The solar cell of claim 1 , further comprising:
a second dielectric region formed over the silicon substrate, wherein the second dielectric region is formed over the back side of solar;
a second emitter region having metal impurities formed over the second dielectric region; and
a second metal contact formed over the second emitter region.
9. The solar cell of claim 8 , wherein the second emitter region comprises polysilicon.
10. A solar cell, the solar cell having a front side which faces the sun during normal operation and a back side opposite the front side, the solar cell comprising:
a silicon substrate, wherein a portion of the silicon substrate has a dopant concentration of approximately less than or equal to 2×10 18 cm −3 and wherein the portion of the silicon substrate is formed at the front side of the solar cell;
a dielectric region formed over the silicon substrate, wherein the dielectric region is formed over the back side of solar;
a first emitter region having metal impurities formed over the dielectric region; and
a first metal contact formed over the first emitter region.
11. The solar cell of claim 10 , wherein the portion of the silicon substrate comprises N-type dopants.
12. The solar cell of claim 10 , wherein the portion of the silicon substrate comprises phosphorus.
13. The solar cell of claim 10 , wherein the portion of the silicon substrate comprises P-type dopants.
14. The solar cell of claim 10 , wherein the portion of the silicon substrate comprises boron.
15. The solar cell of claim 10 , wherein the first emitter region comprises polysilicon.
16. The solar cell of claim 10 , further comprising:
a second emitter region having metal impurities formed over the dielectric region; and
a second metal contact formed over the second emitter region.
17. The solar cell of claim 16 , wherein the second emitter region is separate from the first emitter region.
18. The solar cell of claim 16 , wherein a trench region separates the first emitter region from the second emitter region.
19. The solar cell of claim 16 , wherein the second emitter region comprises polysilicon.
20. The solar cell of claim 16 , wherein the first emitter region comprises a P-type doped polysilicon region and the second emitter region comprises a N-type doped polysilicon region.