Solar cell emitter region fabrication with differentiated p-type and n-type architectures and incorporating a multi-purpose passivation and contact layer

A method of fabricating a solar cell, the method comprising:

• providing a semiconductor substrate having a light-receiving surface and a back surface, the back surface below the light-receiving surface;
• forming an N-type emitter region on the back surface of the semiconductor substrate, wherein the N-type emitter region is a planar layer;
• forming a P-type emitter region on the back surface of the semiconductor substrate, the P-type emitter region comprising polycrystalline silicon having hydrogen therein, and the P-type emitter region electrically insulated and physically isolated from the N-type emitter region by a single dielectric material, the single dielectric material in direct physical contact with the P-type emitter region and with the N-type emitter region, and the single dielectric material confined to sidewalls of the N-type emitter region, wherein the P-type emitter region is a non-planar layer, and wherein the P-type emitter region has an uppermost surface above an uppermost surface of the N-type emitter region, and the P-type emitter region has a bottommost surface below a bottommost surface of the N-type emitter region;
• forming a passivation layer on the P-type emitter region but not on the N-type emitter region, the passivation layer comprising amorphous silicon having hydrogen therein, the passivation layer covering an entirety of a side of the P-type emitter region opposite the semiconductor substrate;
• forming a first conductive contact structure electrically connected to and in direct contact with the N-type emitter region;
• and
• forming a second conductive contact structure electrically connected to the P-type emitter region and in direct contact with the passivation layer, wherein the second conductive contact structure has an uppermost surface below the uppermost surface of the N-type emitter region, wherein the second conductive contact is physically separated from an entirety of the P-type emitter region by the passivation layer.

A method of fabricating a back contact solar cell, the method comprising:

• providing a semiconductor substrate having a light-receiving surface and a back surface, the back surface below the light-receiving surface;
• forming an N-type polycrystalline silicon emitter region on a first thin dielectric layer on the back surface of the semiconductor substrate, wherein the N-type polycrystalline silicon emitter region is a planar layer;
• forming a P-type polycrystalline silicon emitter region on a second thin dielectric layer in a trench formed in the back surface of the semiconductor substrate, the P-type polycrystalline silicon emitter region having hydrogen therein, and the P-type polycrystalline silicon emitter region electrically insulated and physically isolated from the N-type polycrystalline silicon emitter region by a single third thin dielectric layer laterally directly between and in physical contact with both the N-type and the P-type polycrystalline silicon emitter regions, and the single third thin dielectric layer confined to sidewalls of the N-type polycrystalline silicon emitter region, wherein the P-type polycrystalline silicon emitter region is a non-planar layer, and wherein the P-type polycrystalline silicon emitter region has an uppermost surface above an uppermost surface of the N-type polycrystalline silicon emitter region, and the P-type emitter polycrystalline silicon region has a bottommost surface below a bottommost surface of the N-type polycrystalline silicon emitter region;
• forming a P-type silicon layer on the P-type polycrystalline silicon emitter region but not on the N-type polycrystalline silicon emitter region, the P-type silicon layer comprising amorphous silicon having hydrogen therein, the P-type silicon layer covering an entirety of a side of the P-type polycrystalline silicon emitter region opposite the semiconductor substrate;
• forming a first conductive contact structure electrically connected to and in direct contact with the N-type polycrystalline silicon emitter region;
• and
• forming a second conductive contact structure electrically connected to the P-type polycrystalline silicon emitter region and in direct contact with the P-type silicon layer, wherein the second conductive contact structure has an uppermost surface below the uppermost surface of the N-type polycrystalline silicon emitter region, wherein the second conductive contact is physically separated from an entirety of the P-type polycrystalline silicon emitter region by the P-type silicon layer.