Solexel, Inc.

Pranav Anbalagan

Mehrdad M Moslehi

Virendra V Rana

Vivek Saraswat

Heather Deshazer

Jianjun Liang

Solene Coutant

Benjamin Rattle

JianJun Liang

Methods for improving the light trapping characteristics of crystalline silicon solar cells are provided. In one embodiment, the backside surface of a crystalline silicon solar cell substrate is textured with a pulsed laser beam. The textured backside surface of the crystalline silicon solar cell substrate is then annealed to remove damage from the laser texturization process.

Systems and methods for enhanced light trapping in solar cells

A method for making a crystalline silicon solar cell substrate is provided. A doped dielectric layer is deposited over the backside surface of a crystalline silicon substrate, the doped dielectric layer having a polarity opposite the polarity of the crystalline silicon substrate. Portions of the backside surface of the crystalline substrate are exposed through the doped dielectric layer. An overlayer is deposited over the doped dielectric layer and the exposed portions of the backside surface of the crystalline silicon substrate. Pulsed laser ablation of the overlayer is performed with a flat top laser beam on the silicon substrate to form continuous base openings nested within the exposed portions of the backside surface of the crystalline silicon substrate, the flat top laser beam having a beam intensity profile flatter as compared to a Gaussian beam intensity profile and having a rectangular beam cross section. Doped base regions are formed in the crystalline silicon substrate through the continuous base openings.

Method for making a crystalline silicon solar cell substrate utilizing flat top laser beam

Methods for laser irradiation aluminum doping for monocrystalline silicon substrates are provided. According to one aspect of the disclosed subject matter, aluminum metal contacts are formed directly on a surface of a monocrystalline silicon substrate. The aluminum metal contact is selectively heated via laser irradiation, thereby causing the aluminum and a portion of the monocrystalline silicon substrate in proximity to the aluminum to reach a temperature sufficient to allow at least a portion of the silicon to dissolve in the aluminum. The aluminum and the portion of the monocrystalline silicon substrate in proximity to the aluminum is allowed to cool, thereby forming an aluminum-rich doped silicon layer on the monocrystalline silicon substrate.

Laser irradiation aluminum doping for monocrystalline silicon substrates

A method for making a back contact solar cell. Base isolation regions are formed in a crystalline silicon back contact solar cell substrate having a substrate thickness in the range of approximately 1 micron to 100 microns. Pulsed laser ablation of a substance on the crystalline silicon back contact solar cell substrate is performed to form base openings, wherein the substance is at least one of silicon oxide, silicon nitride, aluminum oxide, silicon oxynitride, or silicon carbide. Emitter regions are selectively doped and base regions are selectively doped. Contact openings are formed for the selectively doped base regions and the selectively doped emitter regions. Metallization is formed on the selectively doped base regions and the selectively doped emitter regions.

Laser processing for high-efficiency thin crystalline silicon solar cell fabrication

A method for making an ablated electrically insulating layer on a semiconductor substrate. A first relatively thin layer of at least an undoped glass or undoped oxide is deposited on a surface of a semiconductor substrate having n-type doping. A first relatively thin semiconductor layer having at least one substance chosen from amorphous semiconductor, nanocrystalline semiconductor, microcrystalline semiconductor, or polycrystalline semiconductor is deposited on the relatively thin layer of at least an undoped glass or undoped oxide. At least a layer of borosilicate glass or borosilicate/undoped glass stack is deposited on the relatively thin semiconductor layer. The at least borosilicate glass or borosilicate/undoped glass stack is selectively ablated with a pulsed laser, and the relatively thin semiconductor layer substantially protects the semiconductor substrate from the pulsed laser.

Patterning of silicon oxide layers using pulsed laser ablation

Various laser processing schemes are disclosed for producing various types of hetero-junction and homo-junction solar cells. The methods include base and emitter contact opening, selective doping, metal ablation, annealing to improve passivation, and selective emitter doping via laser heating of aluminum. Also, laser processing schemes are disclosed that are suitable for selective amorphous silicon ablation and selective doping for hetero-junction solar cells. Laser ablation techniques are disclosed that leave the underlying silicon substantially undamaged. These laser processing techniques may be applied to semiconductor substrates, including crystalline silicon substrates, and further including crystalline silicon substrates which are manufactured either through wire saw wafering methods or via epitaxial deposition processes, or other cleavage techniques such as ion implantation and heating, that are either planar or textured/three-dimensional. These techniques are highly suited to thin crystalline semiconductor, including thin crystalline silicon films.

Laser processing schemes are disclosed for producing various types of hetero-junction and homo-junction solar cells. The methods include base and emitter contact opening, selective doping, and metal ablation. Also, laser processing schemes are disclosed that are suitable for selective amorphous silicon ablation and selective doping for hetero-junction solar cells. These laser processing techniques may be applied to semiconductor substrates, including crystalline silicon substrates, and further including crystalline silicon substrates which are manufactured either through wire saw wafering methods or via epitaxial deposition processes, that are either planar or textured/three-dimensional. These techniques are highly suited to thin crystalline semiconductor, including thin crystalline silicon films.

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San Jose, CA, United States of America

Pranav Anbalagan