Multijunction Solar Cells with Group IV/III-V Hybrid Alloys
A method of manufacturing a solar cell by providing a germanium semiconductor growth substrate; and depositing on the semiconductor growth substrate a sequence of layers of semiconductor material forming a solar cell, including a subcell composed of a group IV/III-V hybrid alloy.
1 . A method of manufacturing a solar cell comprising:
providing a germanium semiconductor growth substrate;
depositing on said semiconductor growth substrate a sequence of layers of semiconductor material forming a solar cell, including a subcell composed of a group IV/III-V hybrid alloy.
2 . A method as defined in claim 1 , wherein the group IV/III-V hybrid alloy is GeSiSn.
3 . A method as defined in claim 2 , wherein the GeSiSn subcell has a band gap in the range of 0.8 eV to 1.2 eV.
4 . A method as defined in claim 3 , further comprising a subcell composed of germanium deposited between said GeSiSn subcell and the germanium substrate.
5 . A method as defined in claim 1 , wherein the sequence of layers includes a first GeSiSn subcell having a band gap in the range of 0.91 eV to 0.95 eV, and a second GeSiSn subcell having a band gap in the range of 1.13 eV to 1.24 eV.
6 . A method as defined in claim 1 , wherein said step of depositing a sequence of layers of semiconductor material includes forming a first solar subcell on said substrate composed of GeSiSn and having a first band gap; forming a second solar subcell over said first subcell composed of InGaAs having a second band gap greater than said first band gap; and forming a third solar subcell composed of GaInP over said second solar subcell having a third band gap greater than said second band gap.
7 . A method as defined in claim 1 , wherein said step of depositing a sequence of layers of semiconductor material includes forming a first solar subcell on said substrate composed of Ge and having a first band gap; forming a second solar subcell over said first subcell composed of GeSiSn having a second band gap greater than said first band gap; and forming a third solar subcell composed of InGaAs over said second solar subcell having a third band gap greater than said second band gap; and forming a fourth solar subcell composed of GaInP having a fourth band gap greater than said third band gap and lattice matched to said third solar subcell.
8 . A method as defined in claim 1 , wherein said step of depositing a sequence of layers of semiconductor material includes forming a first solar subcell on said substrate composed of Ge and having a first band gap; forming a second solar subcell over said first subcell composed of GeSiSn having a second band gap greater than said first band gap; and forming a third solar subcell composed of GeSiSn over said second solar subcell having a third band gap greater than said second band gap; and forming a fourth solar subcell composed of InGaAs having a fourth band gap greater than said third band gap and lattice matched to said third solar subcell; forming a fifth solar subcell composed of GaInP having a fifth band gap greater than said fourth band gap and lattice matched to said fourth solar subcell.
9 . A method as defined in claim 1 , wherein some of said layers are deposited with metal organic chemical vapor deposition processes at a temperature around 700° C.
10 . A method as defined in claim 1 , wherein the coefficient of thermal expansion between the growth substrate and the layers of semiconductor material are suitably matched to avoid cracking.
11 . A method as defined in claim 7 , further comprising forming a tunnel diode composed of GeSiSn between the first subcell composed of Ge and the second subcell composed of GeSiSn.
12 . A method as defined in claim 1 , further comprising depositing a BSF layer composed of GeSiSn over said growth substrate.
13 . A method as defined in claim 1 , wherein the group IV/III-V hybrid alloy is deposited by chemical vapor deposition at a temperature around 300° C.
14 . A method as defined in claim 1 , further comprising depositing a Ge buffer layer over said germanium growth substrate.
15 . A method as defined in claim 4 , further comprising forming a GeSiSin BSF layer and a GeSiSn window layer adjacent to said germanium subcell.
16 . A method as defined in claim 4 , wherein the germanium subcell has a band gap of approximately 0.73 eV.
17 . A method as defined in claim 1 , wherein a junction is formed in the group IV/III-V hybrid alloy to form a photovoltaic subcell by the diffusion of As and/or P into the hybrid alloy layer.
18 . A method as defined in claim 1 , further comprising forming window and BSF layers composed of the group IV/III-V hybrid alloy adjacent to the subcell composed of the group IV/III-V hybrid alloy.
19 . A method of manufacturing a solar cell comprising:
providing a semiconductor growth substrate; and
depositing on said semiconductor growth substrate a sequence of layers of semiconductor material forming a solar cell, including at least one layer composed of GeSiSn and one layer grown over the GeSiSn layer composed of Ge.
20 . A multijunction solar cell comprising:
a first solar subcell composed of GeSiSn and having a first band gap;
a second solar subcell composed of GaAs, InGaAsP, or InGaP and disposed over the first solar subcell having a second band gap greater than the first band gap and lattice matched to said first solar subcell; and
a third solar subcell composed of GaInP and disposed over the second solar subcell having a third band gap greater than the second band gap and lattice matched with respect to the second subcell.