Bifacial tandem solar cells
First Claim
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1. A semiconductor device comprising:
- a substrate having a first side and a second side opposite from the first side;
a lower bandgap subcell on the first side of the substrate, the lower bandgap subcell comprising a bottom subcell and grading layers, the bottom subcell and the grading layers comprising non-phosphorous materials and a first periodic table group V material;
a plurality of higher bandgap subcells on the second side of the substrate, the plurality of higher bandgap subcells comprising a second periodic table group V material; and
a protective layer on the lower bandgap subcell, the protective layer serving as a diffusion barrier to phosphorous and dopant atoms and being thermally expansion matched to the lower bandgap subcell,wherein the lower bandgap subcell has a lower bandgap than a bandgap of the substrate, and the plurality of higher bandgap subcells have higher bandgaps than the bandgap of the substrate.
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Abstract
A method of fabricating on a semiconductor substrate bifacial tandem solar cells with semiconductor subcells having a lower bandgap than the substrate bandgap on one side of the substrate and with subcells having a higher bandgap than the substrate on the other including, first, growing a lower bandgap subcell on one substrate side that uses only the same periodic table group V material in the dislocation-reducing grading layers and bottom subcells as is present in the substrate and after the initial growth is complete and then flipping the substrate and growing the higher bandgap subcells on the opposite substrate side which can be of different group V material.
456 Citations
16 Claims
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1. A semiconductor device comprising:
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a substrate having a first side and a second side opposite from the first side; a lower bandgap subcell on the first side of the substrate, the lower bandgap subcell comprising a bottom subcell and grading layers, the bottom subcell and the grading layers comprising non-phosphorous materials and a first periodic table group V material; a plurality of higher bandgap subcells on the second side of the substrate, the plurality of higher bandgap subcells comprising a second periodic table group V material; and a protective layer on the lower bandgap subcell, the protective layer serving as a diffusion barrier to phosphorous and dopant atoms and being thermally expansion matched to the lower bandgap subcell, wherein the lower bandgap subcell has a lower bandgap than a bandgap of the substrate, and the plurality of higher bandgap subcells have higher bandgaps than the bandgap of the substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification