Laser beam shaping for foil-based metallization of solar cells
Approaches for foil-based metallization of solar cells and the resulting solar cells are described. For example, a method of fabricating a solar cell involves locating a metal foil above a plurality of alternating N-type and P-type semiconductor regions disposed in or above a substrate. The method also involves laser welding the metal foil to the alternating N-type and P-type semiconductor regions. The method also involves patterning the metal foil by laser ablating through at least a portion of the metal foil at regions in alignment with locations between the alternating N-type and P-type semiconductor regions. The laser welding and the patterning are performed at the same time.
1. A solar cell, comprising:
a plurality of N-type and P-type semiconductor regions disposed above a substrate;
a metal layer disposed on the N-type and P-type semiconductor regions, the metal layer disposed on and in alignment with the N-type and P-type semiconductor regions; and
a metal foil disposed on and bonded to the metal layer, wherein the bond between the metal foil and the metal layer comprises weld regions, the plurality of weld regions approximately equally spaced from a border between the nearest N-type and P-type semiconductor regions.
2. The solar cell of claim 1 , wherein the metal layer comprises a metal seed layer.
3. The solar cell of claim 1 , wherein the metal layer comprises an aluminum layer.
4. The solar cell of claim 1 , wherein the metal foil comprises an aluminum foil.
5. The solar cell of claim 1 , wherein the N-type and P-type semiconductor regions are N-type and P-type regions in a polycrystalline silicon layer disposed above the substrate.
6. The solar cell of claim 1 , further comprising a thin dielectric layer disposed on the substrate, the thin dielectric layer disposed between the N-type and P-type semiconductor regions and the substrate.