Multijunction solar cells
AssigneeSolAero Technologies Corp.
InventorDaniel Derkacs
Life of this patent
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Abstract
A method of fabricating multijunction solar cell including an upper solar subcell and having an emitter of p conductivity type with a first band gap, and a base of n conductivity type with a second band gap greater than the first band gap; a lower solar subcell disposed below the upper solar subcell having an emitter of p conductivity type with a third band gap, and a base of n conductivity type with a fourth band gap greater than the third band gap; and an intermediate grading interlayer disposed between the upper and lower solar subcells and having a graded lattice constant that matches the upper first subcell on a first side and the second solar subcell on the second side opposite the first side, and having a fifth band gap that is greater than the second band gap of the upper solar subcell.
Claims17
A method of fabricating multijunction solar cell comprising:
- providing a semiconductor growth substrate:
- forming an upper first solar subcell on the semiconductor growth substrate;
- forming a second solar subcell over the upper first solar subcell;
- providing a first electrically conductive contact layer having a first polarity and a second electrically conductive contact layer having a second opposite polarity, wherein the first electrically conductive contact layer is closer to a front-side of the solar cell operable to receive incident light, and the second conductive contact layer is closer to a back-side of the solar cell;
- wherein the upper first solar subcell has an emitter of p conductivity type with a first band gap, and a base of n+ conductivity type with a second band gap greater than the first band gap, the emitter and base of the upper first solar subcell forming a p-n junction;
- wherein the second solar subcell is epitaxially grown over the upper first solar subcell and having an emitter of p conductivity type with a third band gap, and a base of n+ conductivity type, the emitter and base of the second solar subcell forming a p-n junction;
- forming a tunnel diode over the upper first solar subcell and below the second solar subcell, the tunnel diode being directly adjacent to the base of the upper first solar subcell,
- wherein the emitter of the upper first solar subcell is doped in the range of 1×1017 free carriers per cubic centimeter to 5×1017 free carries per cubic centimeter,
- the upper first solar subcell and the second solar subcell being disposed between the first and second electrically conductive contact layers such that the p conductivity type emitter of the upper first solar subcell is closer to the first electrically conductive contact layer than are the n+ conductivity type base of the upper first solar subcell and the emitter and base of the second solar subcell, and such that the n+ conductivity type base of the second solar subcell is closer to the second electrically conductive contact layer than are the p conductivity type emitter of the second solar subcell and the base and emitter of the upper first solar subcell;
- and
- removing the semiconductor growth substrate.
Dependencies are inferred from the claim text.