Nitrided barrier layers for solar cells

Abstract

The present invention relates to polysilicon emitter solar cells, and more particularly to polysilicon emitter solar cells with hyperabrupt junctions, and methods for making such solar cells. According to one aspect, a polysilicon emitter solar cell according to the invention includes a nitrided tunnel insulator. The nitridation prevents boron diffusion, enabling a hyperabrupt junction for a p-poly on n-Si device. According to another aspect, a nitrided oxide (DPN) is used in a tunnel oxide layer of a MIS solar cell structure. The DPN layer minimizes plasma damage, resulting in improved interface properties. An overlying polysilicon emitter can then provide a low sheet resistance emitter without heavy doping effects in the substrate, excess recombination, or absorption, and is a significant improvement over a conventional diffused emitter or TCO. According to another aspect, the invention includes a method for making a solar cell structure that is functionally equivalent to a selective emitter, but without the requirement for multiple diffusions, long diffusions, aligned lithography, or fine contact holes.

Dependencies are inferred from the claim text.