Method of forming emitters for a back-contact solar cell
Methods of forming emitters for back-contact solar cells are described. In one embodiment, a method includes forming a first solid-state dopant source above a substrate. The first solid-state dopant source includes a plurality of regions separated by gaps. Regions of a second solid-state dopant source are formed above the substrate by printing.
1. A method of forming emitters for a back-contact solar cell, the method comprising:
forming, by chemical vapor deposition, a first solid-state dopant source of a first conductivity type above a substrate, the first solid-state dopant source comprising a plurality of regions separated by gaps; and
forming, by printing, regions of a second solid-state dopant source of a second conductivity type above the substrate, in the gaps of the plurality of regions of the first solid-state dopant source but not in contact with the plurality of regions of the first solid-state dopant source, wherein the first conductivity type is opposite the second conductivity type.
2. The method of claim 1 , wherein the regions of the second solid-state dopant source are spaced apart from the plurality of regions of the first solid-state dopant source, the method further comprising:
forming trenches partially into the substrate, between the regions of the second solid-state dopant source and the plurality of regions of the first solid-state dopant source; and
heating the substrate to drive dopants from the first and second solid-state dopant sources, wherein the heating hardens the second solid-state dopant source.
3. The method of claim 2 , further comprising:
subsequent to the forming the trenches and to the heating, texturizing portions of the substrate exposed by the trenches, wherein the hardened second solid-state dopant source acts as a mask during the texturizing.
4. The method of claim 1 , further comprising:
prior to forming the first solid-state dopant source, forming a thin dielectric layer on the substrate; and
forming a polysilicon layer on the thin dielectric layer, wherein the first solid-state dopant source and the second solid-state dopant source are formed on the polysilicon layer.
5. The method of claim 4 , further comprising:
heating the substrate to drive dopants from the first and second solid-state dopant sources into the polysilicon layer.
6. The method of claim 1 , wherein the substrate is a bulk crystalline silicon substrate, the first solid-state dopant source and the second solid-state dopant source are formed on the bulk crystalline silicon substrate; and
the bulk crystalline silicon substrate is heated to drive dopants from the first and second solid state dopant sources into the bulk crystalline silicon substrate.
7. The method of claim 1 , wherein the second solid-state dopant source comprises a spin-on-glass precursor material or a nanoparticle material.
8. The method of claim 1 , wherein the first conductivity type is p-type, the second conductivity type is n-type, and the first solid-state dopant source comprises boron silicate glass (BSG).
9. The method of claim 1 , wherein the first conductivity type is n-type, the second conductivity type is p-type, and the first solid-state dopant source comprises phosphorus silicate glass (PSG).