Abstract: A solar cell includes a portion of a Germanium layer having a first side and a second side. The second side has properties consistent with a grinding and etching operation to thin a Germanium wafer to form the Germanium layer. Edges of the portion of the Germanium layer may have properties consistent with dicing using a diamond-coated saw. The portion of the Germanium layer may have a thickness of less than 150 micrometers. Compound semiconductor materials and circuitry are coupled to the first side of the portion of the Germanium layer to define a multijunction solar cell. A fused silica cover glass is coupled to the multijunction solar cell via a silicone-based adhesive.

Abstract: A solar cell includes a Germanium wafer having a first side and a second side. The first side has properties consistent with a grinding operation, and edges of the Germanium wafer have properties consistent with a diamond-coated saw blade cut. The Germanium wafer has a thickness of approximately two-hundred five micrometers. The solar cell also includes a Gallium Arsenide-based triple junction solar cell coupled to the second side of the Germanium wafer. The solar cell also includes a fused silica cover coupled to the Gallium Arsenide-based triple junction solar cell via a silicone-based adhesive.

Abstract: An IMM solar cell and an associated method of fabricating an IMM solar cell are provided. In the context of a method, a first subcell may be formed upon a temporary substrate and a second subcell may be formed upon the first subcell. The second subcell may have a smaller band gap than the first subcell. The method may also bond the first and second subcells to a silicon subcell and then remove the temporary substrate. In the context of an IMM solar cell, the IMM solar cell includes first and second subcells with the first subcell disposed upon the second subcell and the second subcell having a smaller band gap than the first subcell. The IMM solar cell may also include a silicon subcell supporting the first and second subcells thereupon with a metal-to-metal bond between the silicon subcell and the second subcell.

Abstract: A solar cell structure including a silicon carrier defining a front side and a back side, and including an N-type portion having an exposed portion on the front side of the carrier and a P-type portion having an exposed portion on the front side of the carrier, the N-type portion and the P-type portion defining a P-N junction, and a solar cell defining a front side and a back side, wherein the solar cell is connected to the front side of the carrier such that the back side of the solar cell is electrically coupled to the exposed portion of the N-type portion, and wherein the front side of the solar cell is electrically coupled to the exposed portion of the P-type portion.

Abstract: An IMM solar cell and an associated method of fabricating an IMM solar cell are provided. In the context of a method, a first subcell may be formed upon a temporary substrate and a second subcell may be formed upon the first subcell. The second subcell may have a smaller band gap than the first subcell. The method may also bond the first and second subcells to a silicon subcell and then remove the temporary substrate. In the context of an IMM solar cell, the IMM solar cell includes first and second subcells with the first subcell disposed upon the second subcell and the second subcell having a smaller band gap than the first subcell. The IMM solar cell may also include a silicon subcell supporting the first and second subcells thereupon with a metal-to-metal bond between the silicon subcell and the second subcell.

Abstract: A solar cell structure including a silicon carrier defining a front side and a back side, and including an N-type portion having an exposed portion on the front side of the carrier and a P-type portion having an exposed portion on the front side of the carrier, the N-type portion and the P-type portion defining a P-N junction, and a solar cell defining a front side and a back side, wherein the solar cell is connected to the front side of the carrier such that the back side of the solar cell is electrically coupled to the exposed portion of the N-type portion, and wherein the front side of the solar cell is electrically coupled to the exposed portion of the P-type portion.

Abstract: In one embodiment, a method of forming a multijunction solar cell having lattice mismatched layers and lattice-matched layers comprises growing a top subcell having a first band gap over a growth semiconductor substrate. A middle subcell having a second band gap is grown over the top subcell, and a lower subcell having a third band gap is grown over the middle subcell. The lower subcell is substantially lattice-mismatched with respect to the growth semiconductor substrate. The first band gap of the top subcell is larger than the second band gap of the middle subcell. The second band gap of the middle subcell is larger than the third band gap of the lower subcell. A support substrate is formed over the lower subcell, and the growth semiconductor substrate is removed. In various embodiments, the multijunction solar cell may further comprise additional lower subcells. A parting layer may also be provided between the growth substrate and the top subcell in certain embodiments.

Abstract: In one embodiment, a method of forming a multijunction solar cell having lattice mismatched layers and lattice-matched layers comprises growing a top subcell having a first band gap over a growth semiconductor substrate. A middle subcell having a second band gap is grown over the top subcell, and a lower subcell having a third band gap is grown over the middle subcell. The lower subcell is substantially lattice-mismatched with respect to the growth semiconductor substrate. The first band gap of the top subcell is larger than the second band gap of the middle subcell. The second band gap of the middle subcell is larger than the third band gap of the lower subcell. A support substrate is formed over the lower subcell, and the growth semiconductor substrate is removed. In various embodiments, the multijunction solar cell may further comprise additional lower subcells. A parting layer may also be provided between the growth substrate and the top subcell in certain embodiments.

Abstract: A high efficiency solar cell comprises: (a) a germanium substrate having a front surface and a back surface; (b) a back-metal contact on the back surface of the germanium substrate; (c) a first semiconductor cell comprising (1) a GaAs p-n junction formed from an n-GaAs and a p-GaAs layer, the n-GaAs layer formed on the front surface of the n-germanium substrate, and (2) a p-(Al,Ga)As window layer, the p-(Al,Ga)As window layer formed on the p-GaAs layer; (d) a tunnel diode comprising a GaAs p.sup.+ -n.sup.+ junction formed from a p.sup.+ -GaAs layer and an n.sup.+ -GaAs layer, the p.sup.+ -GaAs layer formed on the p-(Al,Ga)As window layer; and (e) a second semiconductor cell comprising (1) a (Ga,In)P p-n junction formed from an n-(Ga,In)P layer and a p-(Ga,In)P layer, the n(Ga,In)P layer formed on the n.sup.

Abstract: A gallium-arsenide solar cell has a germanium substrate cut at a special angle, with its surface generally perpendicular to the 001 axis, but tilted by about six to fifteen degrees toward the direction generally about half-way between the 011 and the 111 axial directions. To avoid the cascade effect the junction with the substrate may be passivated or photovoltaically inhibited by initiating vapor deposition of GaAs at a temperature below 700.degree. C. and rapidly ramping the temperature up to normal vapor deposition temperatures. Poisoning of the GaAs layer by germanium may be prevented inexpensively by using a silicon dioxide coating on one side of the germanium substrate.