Solar cells having differentiated P-type and N-type architectures
Methods of fabricating solar cell emitter regions with differentiated P-type and N-type region architectures, and the resulting solar cells, are described herein. In an example, a solar cell includes an N-type semiconductor substrate having a light-receiving surface and a back surface. A plurality of N-type polycrystalline silicon regions is disposed on a first thin dielectric layer disposed on the back surface of the N-type semiconductor substrate. A plurality of P-type polycrystalline silicon regions is disposed on a second thin dielectric layer disposed in a corresponding one of a plurality of trenches interleaving the plurality of N-type polycrystalline silicon regions in the back surface of the N-type semiconductor substrate.
1. A solar cell, comprising:
an N-type semiconductor substrate having a light-receiving surface and a back surface;
a plurality of N-type polycrystalline silicon regions disposed on a first thin dielectric layer disposed on the back surface of the N-type semiconductor substrate; and
a plurality of P-type polycrystalline silicon regions disposed on a second thin dielectric layer disposed in a corresponding one of a plurality of trenches interleaving the plurality of N-type polycrystalline silicon regions in the back surface of the N-type semiconductor substrate, wherein a total area of the plurality of N-type polycrystalline silicon regions is greater than a total area of the plurality of P-type polycrystalline silicon regions in the plurality of corresponding trenches.
2. The solar cell of claim 1 , wherein the total area of the plurality of N-type polycrystalline silicon regions is greater than the total area of the plurality of P-type polycrystalline silicon regions in the plurality of corresponding trenches by a ratio of 15:1 or more.
3. The solar cell of claim 1 , wherein the plurality of P-type polycrystalline silicon regions overlap a portion of the plurality of N-type polycrystalline silicon regions.
4. The solar cell of claim 1 , wherein each of the plurality of N-type polycrystalline silicon regions has a width greater than a width of each of the plurality of P-type polycrystalline silicon regions by a ratio of 5:1 or more.
5. The solar cell of claim 1 , wherein each of the plurality of N-type polycrystalline silicon regions has a thickness relative to a thickness of each of the plurality of P-type polycrystalline silicon regions by a ratio of 3:1 or less.
6. The solar cell of claim 1 , wherein each of the plurality of trenches has a depth approximately in the range of 0.1-3 microns from the back surface and into the N-type semiconductor substrate.
7. The solar cell of claim 1 , wherein each of the plurality of trenches has a texturized surface.
8. The solar cell of claim 1 , further comprising:
a third thin dielectric layer disposed laterally directly between adjacent ones of the N-type polycrystalline silicon regions and the P-type polycrystalline silicon regions.
9. The solar cell of claim 1 , further comprising:
a plurality of conductive contact structures electrically connected to the N-type polycrystalline silicon regions and the P-type polycrystalline silicon regions.