Method of fabricating a solar cell with a tunnel dielectric layer
View Patent ↗Methods of fabricating solar cells with tunnel dielectric layers are described. Solar cells with tunnel dielectric layers are also described.
1. A method of fabricating a solar cell, the method comprising:
consuming a portion of a substrate of the solar cell to provide a surface oxide layer of the substrate by exposing the substrate to a wet chemical solution; and
heating the surface oxide layer in a dry atmosphere at a temperature near or above 900 degrees Celsius to convert the surface oxide layer to a tunnel dielectric layer of the solar cell.
2. The method of claim 1 , wherein the surface oxide layer is exposed to a temperature near or above 900 degrees Celsius only once during the fabricating.
3. The method of claim 1 , wherein the wet chemical solution comprises an oxidizer selected from the group consisting of ozone (O 3 ) and hydrogen peroxide (H 2 O 2 ).
4. The method of claim 3 , wherein the wet chemical solution and the substrate are exposed to visible light radiation during the exposing.
5. The method of claim 1 , further comprising:
subsequent to the exposing and prior to the heating, heating the surface oxide layer from a temperature below 500 degrees Celsius, to a temperature of approximately 565 degrees Celsius, and then cooling back to a temperature below 500 degrees Celsius.
6. The method of claim 1 , further comprising:
forming a material layer above the surface oxide layer prior to the heating.
7. The method of claim 6 , wherein the material layer is an amorphous silicon layer, and wherein the amorphous silicon layer is crystallized to a polysilicon layer during the heating.
8. The method of claim 7 , further comprising:
forming a metal contact above the polysilicon layer.
9. The method of claim 1 , wherein the substrate comprises silicon and the oxide layer comprises silicon oxide.
10. The method of claim 1 , wherein the substrate is a bulk silicon substrate.
11. A method of fabricating a solar cell, the method comprising:
consuming, at a temperature less than 600 degrees Celsius, a portion of a substrate of the solar cell to provide a surface oxide layer of the substrate by thermal oxidation; and
heating the surface oxide layer in a dry atmosphere at a temperature near or above 900 degrees Celsius to convert the surface oxide layer to a tunnel dielectric layer of the solar cell.
12. The method of claim 11 , wherein the surface oxide layer is exposed to a temperature near or above 900 degrees Celsius only once during the fabricating.
13. The method of claim 11 , wherein the surface oxide layer is formed by a low-pressure thermal oxidation process.
14. The method of claim 13 , wherein the low-pressure thermal oxidation process is performed at a temperature approximately in the range of 500-580 degrees Celsius in an atmosphere comprising oxygen (O 2 ).
15. The method of claim 11 , further comprising:
forming a material layer above the surface oxide layer prior to the heating.
16. The method of claim 15 , wherein the material layer is an amorphous silicon layer, and wherein the amorphous silicon layer is crystallized to a polysilicon layer during the heating.
17. The method of claim 16 , further comprising:
forming a metal contact above the polysilicon layer.
18. The method of claim 11 , wherein the substrate comprises silicon and the oxide layer comprises silicon oxide.
19. The method of claim 11 , wherein the substrate is a bulk silicon substrate.
20. The method of claim 11 , further comprising:
subsequent to the forming and prior to the heating, heating the surface oxide layer from a temperature below 500 degrees Celsius, to a temperature of approximately 565 degrees Celsius, and then cooling back to a temperature below 500 degrees Celsius.