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US 11,380,813 B2Granted
Metamorphic solar cells
AssigneeSolAero Technologies Corp.
InventorsZachary Bittner, John Hart, Samantha Whipple, Nathaniel Miller, Daniel Derkacs
Life of this patent
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Abstract
A multijunction solar cell including a metamorphic layer, and particularly the design and specification of the composition, lattice constant, and band gaps of various layers above the metamorphic layer in order to achieve reduction in “bowing” of the semiconductor wafer caused by the lattice mismatch of layers associated with the metamorphic layer.
Claims22
A method of manufacturing a multijunction solar cell comprising:
- providing a substantially circular semiconductor wafer having a circumferential edge, the semiconductor wafer forming a growth substrate;
- forming a first solar subcell over or in the growth substrate;
- growing a grading interlayer over the growth substrate, followed by growing a sequence of layers of semiconductor material using a deposition process to form a solar cell comprising a plurality of subcells including a second subcell disposed over the growth substrate, and at least a third subcell disposed over the second subcell;
- wherein the grading interlayer has a band gap equal to or greater than that of the second subcell and is compositionally graded to lattice match the growth substrate on one side and the second subcell on the other side;
- the grading interlayer being composed of any of the As, P, N, Sb based III-V compound semiconductors subject to the constraints of having the in-plane lattice parameter of each of the sublayers of the grading interlayer throughout its thickness being greater than or equal to the lattice constant of the growth substrate, and includes N step-graded sublayers where N is an integer, and the value of N is 2<N<10, wherein each successive sublayer has an incrementally greater lattice constant than the sublayer below it and grown in such a manner that each sublayer is fully relaxed;
- growing a first wafer bowing inhibition layer directly over the uppermost sublayer of the grading interlayer, such bowing inhibition layer having an in-plane lattice constant greater than the in-plane lattice constant of the uppermost sublayer of the grading interlayer, the first wafer bowing inhibition layer having a thickness at least twice that of each and every sublayer of the grading interlayer;
- and
- growing a second wafer bowing inhibition layer directly over the first wafer bowing inhibition layer.
5 more elements
A method of manufacturing a multijunction solar cell comprising:
- providing a growth substrate;
- forming a first solar subcell over or in the growth substrate;
- growing a grading interlayer over the growth substrate, followed by growing a sequence of layers of semiconductor material using a deposition process to form a solar cell comprising a plurality of subcells including a second subcell disposed over the growth substrate, and at least a third subcell disposed over the second subcell;
- wherein the grading interlayer has a band gap equal to or greater than that of the second subcell and is compositionally graded to lattice match the growth substrate on one side and the second subcell on the other side;
- the grading interlayer having sublayers in which the in-plane lattice parameter of each of the sublayers throughout its thickness being greater than or equal to that of the lattice constant of the growth substrate, and including a plurality of N step-graded sublayers where N is an integer and the value of N is in the range of 2<N<10, wherein each successive sublayer has an incrementally greater lattice constant than the sublayer below it and grown in such a manner that each sublayer is fully relaxed;
- growing a first wafer bowing inhibition layer having a thickness at least twice that of the underlying step-graded sublayer and disposed directly over the uppermost sublayer of the grading interlayer, such bowing inhibition layer, the wafer bowing inhibition layer having a different set of constituent elements than the directly adjacent layers above such layer and below such layer and being partially relaxed, and
- growing a second wafer bowing inhibition layer directly over the first wafer bowing inhibition layer and having an aluminum content in excess of 50% by mole fraction of the constituent material of the second wafer bowing inhibition layer.
4 more elements
Dependencies are inferred from the claim text.