Abstract: A solar cell is fabricated by etching one or more of its layers without substantially etching another layer of the solar cell. In one embodiment, a copper layer in the solar cell is etched without substantially etching a topmost metallic layer comprising tin. For example, an etchant comprising sulfuric acid and hydrogen peroxide may be employed to etch the copper layer selective to the tin layer. A particular example of the aforementioned etchant is a Co-Bra Etch® etchant modified to comprise about 1% by volume of sulfuric acid, about 4% by volume of phosphoric acid, and about 2% by volume of stabilized hydrogen peroxide. In one embodiment, an aluminum layer in the solar cell is etched without substantially etching the tin layer. For example, an etchant comprising potassium hydroxide may be employed to etch the aluminum layer without substantially etching the tin layer.

Abstract: A method of fabricating a solar cell can include forming a dielectric region on a silicon substrate. The method can also include forming an emitter region over the dielectric region and forming a dopant region on a surface of the silicon substrate. In an embodiment, the method can include heating the silicon substrate at a temperature above 900 degrees Celsius to getter impurities to the emitter region and drive dopants from the dopant region to a portion of the silicon substrate.

Abstract: The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

Abstract: Methods of fabricating solar cell emitter regions using substrate-level ion implantation, and resulting solar cells, are described. In an example, a method of fabricating a solar cell involves forming a lightly doped region in a semiconductor substrate by ion implantation, the lightly doped region of a first conductivity type of a first concentration. The method also involves forming a first plurality of dopant regions of the first conductivity type of a second, higher, concentration by ion implantation, the first plurality of dopant regions overlapping with a first portion of the lightly doped region. The method also involves forming a second plurality of dopant regions by ion implantation, the second plurality of dopant regions having a second conductivity type of a concentration higher than the first concentration, and the second plurality of dopant regions overlapping with a second portion of the lightly doped region and alternating with but not overlapping the first plurality of dopant regions.

Abstract: A solar cell and a solar laminate are described. The solar cell can have a front side which faces the sun during normal operation and a back side opposite front side. The solar cell can include conductive contacts having substantially reflective outer regions disposed on the back side of the solar cell. The solar laminate can include a first encapsulant, the first encapsulant disposed on the back side of the solar cell and a second encapsulant. The solar laminate can include the solar cell laminated between the first and second encapsulant. The substantially reflective outer regions of the conductive contacts and the first encapsulant can be configured to scatter and/or diffuse light at the back side of the solar laminate for substantial light collection at the back side of the solar cell. Methods of fabricating the solar cell are also described herein.

Abstract: A solar cell includes polysilicon P-type and N-type doped regions on a backside of a substrate, such as a silicon wafer. A trench structure separates the P-type doped region from the N-type doped region. Each of the P-type and N-type doped regions may be formed over a thin dielectric layer. The trench structure may include a textured surface for increased solar radiation collection. Among other advantages, the resulting structure increases efficiency by providing isolation between adjacent P-type and N-type doped regions, thereby preventing recombination in a space charge region where the doped regions would have touched.

Abstract: The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

Abstract: A method of high reverse current burn-in of solar cells and a solar cell with a burned-in bypass diode are described herein. In one embodiment, high reverse current burn-in of a solar cell with a tunnel oxide layer induces low breakdown voltage in the solar cell. Soaking a solar cell at high current can also reduce the difference in voltage of defective and non-defective areas of the cell.

Abstract: A solar cell is disclosed. The solar cell has a front side facing the sun during normal operation, and a back side facing away from the sun. The solar cell comprises a silicon substrate, a first polysilicon layer with a region of doped polysilicon on the back side of the substrate. The solar cell also comprises a second polysilicon layer with a second region of doped polysilicon on the back side of the silicon substrate. The second polysilicon layer at least partially covers the region of doped polysilicon. The solar cell also comprises a resistive region disposed in the first polysilicon layer. The resistive region extends from an edge of the second region of doped polysilicon. The resistive region can be formed by ion implantation of oxygen into the first polysilicon layer.

Abstract: Solar cells having emitter regions composed of wide bandgap semiconductor material are described. In an example, a method includes forming, in a process tool having a controlled atmosphere, a thin dielectric layer on a surface of a semiconductor substrate of the solar cell. The semiconductor substrate has a bandgap. Without removing the semiconductor substrate from the controlled atmosphere of the process tool, a semiconductor layer is formed on the thin dielectric layer. The semiconductor layer has a bandgap at least approximately 0.2 electron Volts (eV) above the bandgap of the semiconductor substrate.

Abstract: A solar cell is disclosed. The solar cell has a front side facing the sun during normal operation, and a back side facing away from the sun. The solar cell comprises a silicon substrate, a first polysilicon layer with a region of doped polysilicon on the back side of the substrate. The solar cell also comprises a second polysilicon layer with a second region of doped polysilicon on the back side of the silicon substrate. The second polysilicon layer at least partially covers the region of doped polysilicon. The solar cell also comprises a resistive region disposed in the first polysilicon layer. The resistive region extends from an edge of the second region of doped polysilicon. The resistive region can be formed by ion implantation of oxygen into the first polysilicon layer.

Abstract: A method of fabricating a solar cell is disclosed. The method can include forming a dielectric region on a surface of a solar cell structure and forming a metal layer on the dielectric layer. The method can also include configuring a laser beam with a particular shape and directing the laser beam with the particular shape on the metal layer, where the particular shape allows a contact to be formed between the metal layer and the solar cell structure.

Abstract: A solar cell includes polysilicon P-type and N-type doped regions on a backside of a substrate, such as a silicon wafer. A trench structure separates the P-type doped region from the N-type doped region. Each of the P-type and N-type doped regions may be formed over a thin dielectric layer. The trench structure may include a textured surface for increased solar radiation collection. Among other advantages, the resulting structure increases efficiency by providing isolation between adjacent P-type and N-type doped regions, thereby preventing recombination in a space charge region where the doped regions would have touched.

Abstract: Solar cells having emitter regions composed of wide bandgap semiconductor material are described. In an example, a method includes forming, in a process tool having a controlled atmosphere, a thin dielectric layer on a surface of a semiconductor substrate of the solar cell. The semiconductor substrate has a bandgap. Without removing the semiconductor substrate from the controlled atmosphere of the process tool, a semiconductor layer is formed on the thin dielectric layer. The semiconductor layer has a bandgap at least approximately 0.2 electron Volts (eV) above the bandgap of the semiconductor substrate.

Abstract: 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.

Abstract: A method of fabricating a solar cell can include forming a dielectric region on a silicon substrate. The method can also include forming an emitter region over the dielectric region and forming a dopant region on a surface of the silicon substrate. In an embodiment, the method can include heating the silicon substrate at a temperature above 900 degrees Celsius to getter impurities to the emitter region and drive dopants from the dopant region to a portion of the silicon substrate.

Abstract: In one embodiment, harmful solar cell polarization is prevented or minimized by providing a conductive path that bleeds charge from a front side of a solar cell to the bulk of a wafer. The conductive path may include patterned holes in a dielectric passivation layer, a conductive anti-reflective coating, or layers of conductive material formed on the top or bottom surface of an anti-reflective coating, for example. Harmful solar cell polarization may also be prevented by biasing a region of a solar cell module on the front side of the solar cell.

Abstract: Approaches for the foil-based metallization of solar cells and the resulting solar cells are described. In an example, a solar cell includes a substrate. A plurality of alternating N-type and P-type semiconductor regions is disposed in or above the substrate. A conductive contact structure is disposed above the plurality of alternating N-type and P-type semiconductor regions. The conductive contact structure includes a plurality of metal seed material regions providing a metal seed material region disposed on each of the alternating N-type and P-type semiconductor regions. A metal foil is disposed on the plurality of metal seed material regions, the metal foil having anodized portions isolating metal regions of the metal foil corresponding to the alternating N-type and P-type semiconductor regions.

Abstract: Methods of fabricating solar cell emitter regions using substrate-level ion implantation, and resulting solar cells, are described. In an example, a method of fabricating a solar cell involves forming a lightly doped region in a semiconductor substrate by ion implantation, the lightly doped region of a first conductivity type of a first concentration. The method also involves forming a first plurality of dopant regions of the first conductivity type of a second, higher, concentration by ion implantation, the first plurality of dopant regions overlapping with a first portion of the lightly doped region. The method also involves forming a second plurality of dopant regions by ion implantation, the second plurality of dopant regions having a second conductivity type of a concentration higher than the first concentration, and the second plurality of dopant regions overlapping with a second portion of the lightly doped region and alternating with but not overlapping the first plurality of dopant regions.

Abstract: A method of fabricating a solar cell is disclosed. The method can include forming a dielectric region on a surface of a solar cell structure and forming a metal layer on the dielectric layer. The method can also include configuring a laser beam with a particular shape and directing the laser beam with the particular shape on the metal layer, where the particular shape allows a contact to be formed between the metal layer and the solar cell structure.