Solar cell emitter region fabrication with differentiated p-type and n-type region architectures
View Patent ↗Methods of fabricating solar cell emitter regions with differentiated P-type and N-type regions architectures, and resulting solar cells, are described. In an example, a back contact solar cell includes a substrate having a light-receiving surface and a back surface. A first polycrystalline silicon emitter region of a first conductivity type is disposed on a first thin dielectric layer disposed on the back surface of the substrate. A second polycrystalline silicon emitter region of a second, different, conductivity type is disposed on a second thin dielectric layer disposed on the back surface of the substrate. A third thin dielectric layer is disposed laterally directly between the first and second polycrystalline silicon emitter regions. A first conductive contact structure is disposed on the first polycrystalline silicon emitter region. A second conductive contact structure is disposed on the second polycrystalline silicon emitter region.
1. A back contact solar cell, comprising:
a substrate having a light-receiving surface and a back surface;
a first polycrystalline silicon emitter region of a first conductivity type disposed on a first thin dielectric layer disposed on the back surface of the substrate;
a second polycrystalline silicon emitter region of a second, different, conductivity type disposed on a second thin dielectric layer disposed on the back surface of the substrate;
a third thin dielectric layer disposed laterally directly between the first and second polycrystalline silicon emitter regions;
a first conductive contact structure disposed on the first polycrystalline silicon emitter region; and
a second conductive contact structure disposed on the second polycrystalline silicon emitter region, wherein the second polycrystalline silicon emitter region and the second thin dielectric layer are disposed in a recess disposed in the substrate and the first polycrystalline silicon emitter region overlaps the second polycrystalline silicon emitter region.
2. The back contact solar cell of claim 1 , further comprising:
an insulator layer disposed on the first polycrystalline silicon emitter region, wherein the first conductive contact structure is disposed through the insulator layer, and wherein a portion of the second polycrystalline silicon emitter region overlaps the insulator layer but is separate from the first conductive contact structure.
3. The back contact solar cell of claim 1 , further comprising:
an insulator layer disposed on the first polycrystalline silicon emitter region; and
a polycrystalline silicon layer of the second conductivity type disposed on the insulator layer, wherein the first conductive contact structure is disposed through the polycrystalline silicon layer of the second conductivity type and through the insulator layer.
4. The back contact solar cell of claim 1 , wherein the recess has a texturized surface.
5. The back contact solar cell of claim 1 , wherein the first polycrystalline silicon emitter region and the first thin dielectric layer are disposed on a flat portion of the back surface of the substrate, and wherein the second polycrystalline silicon emitter region and the second thin dielectric layer are disposed on a texturized portion of the back surface of the substrate.
6. The back contact solar cell of claim 1 , wherein the first and second conductive contact structures each comprises an aluminum-based metal seed layer disposed on the first and second polycrystalline silicon emitter regions, respectively, and each further comprises a metal layer disposed on the aluminum-based metal seed layer.
7. The back contact solar cell of claim 1 , wherein the first and second conductive contact structures each comprises a metal silicide layer disposed on the first and second polycrystalline silicon emitter regions, respectively, and each further comprises a metal layer disposed on the metal silicide layer.
8. The back contact solar cell of claim 7 , wherein the metal silicide layer comprises a material selected from the group consisting of titanium silicide (TiSi 2 ), cobalt silicide (CoSi 2 ), tungsten silicide (WSi 2 ), and nickel silicide (NiSi or NiSi 2 ).
9. The back contact solar cell of claim 1 , further comprising:
a fourth thin dielectric layer disposed on the light-receiving surface of the substrate;
a polycrystalline silicon layer of the second conductivity type disposed on the fourth thin dielectric layer; and
an anti-reflective coating (ARC) layer disposed on the polycrystalline silicon layer of the second conductivity type.
10. The back contact solar cell of claim 1 , wherein the substrate is an N-type monocrystalline silicon substrate, the first conductivity type is P-type, and the second conductivity type is N-type.
11. The back contact solar cell of claim 1 , wherein all of the first, second and third thin dielectric layers comprise silicon dioxide.