Abstract: A method of processing a silicon substrate can include etching the silicon substrate with a first etchant having a first concentration and etching with a second etchant having a second concentration. In an embodiment, the second concentration of the second etchant can be greater than the first concentration of the first etchant. In one embodiment, the first etchant can be a different type of etchant than the second etchant. In an embodiment, the first and second etchant can be the same type of etchant. In some embodiments the silicon substrate can be cleaned with a first cleaning solution to remove contaminants from the silicon substrate prior to etching with the first etchant. In an embodiment, the silicon substrate can be cleaned with a second cleaning solution after etching the silicon substrate with a second etchant.

Abstract: 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.