Intevac, Inc.

Edward S Murrer

Babak Adibi

Solar cells and other semiconductor devices are fabricated more efficiently and for less cost using an implanted doping fabrication system. A system for implanting a semiconductor substrate includes an ion source (such as a single-species delivery module), an accelerator to generate from the ion source an ion beam having an energy of no more than 150 kV, and a beam director to expose the substrate to the beam. In one embodiment, the ion source is single-species delivery module that includes a single-gas delivery element and a single-ion source. Alternatively, the ion source is a plasma source used to generate a plasma beam. The system is used to fabricate solar cells having lightly doped photo-receptive regions and more highly doped grid lines. This structure reduces the formation of 'dead layers' and improves the contact resistance, thereby increasing the efficiency of a solar cell.

Application specific implant system and method for use in solar cell fabrications

Solar cells in accordance with the present invention have reduced ohmic losses. These cells include photo-receptive regions that are doped less densely than adjacent selective emitter regions. The photo-receptive regions contain multiple four-sided pyramids that decrease the amount of light lost to the solar cell by reflection. The smaller doping density in the photo-receptive regions results in less blue light that is lost by electron-hole recombination. The higher doping density in the selective emitter region allows for better contacts with the metallic grid coupled to the multiple emitter regions. Preferably, the selective emitter and photo-receptive regions are both implanted using a narrow ion beam containing the dopants.

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Aptos, CA, United States of America

Edward S Murrer