Abstract: Apparatus and Method for Optimizing the Efficiency of a Bypass Diode in Solar Cells. In a preferred embodiment, a layer of TiAu is placed in an etch in a solar cell with a contact at a doped layer of GaAs. Electric current is conducted through a diode and away from the main cell by passing through the contact point at the GaAs and traversing a lateral conduction layer. These means of activating, or “turning on” the diode, and passing the current through the circuit results in greater efficiencies than in prior art devices. The diode is created during the manufacture of the other layers of the cell and does not require additional manufacturing.

Abstract: A multijunction solar cell including an upper first solar subcell, and the base-emitter junction of the upper first solar subcell being a homojunction; a second solar subcell adjacent to said first solar subcell; a third solar subcell adjacent to said second solar subcell. A first graded interlayer is provided adjacent to said third solar subcell. A fourth solar subcell is provided adjacent to said first graded interlayer, said fourth subcell is lattice mismatched with respect to said third subcell. A second graded interlayer is provided adjacent to said fourth solar subcell; and a lower fifth solar subcell is provided adjacent to said second graded interlayer, said lower fifth subcell is lattice mismatched with respect to said fourth subcell.

Abstract: A multijunction solar cell including an upper first solar subcell having a first band gap; a second solar subcell adjacent to the first solar subcell and having a second band gap smaller than the first band gap; a graded interlayer adjacent to the second solar subcell, the first graded interlayer having a third band gap greater than the second band gap; and a third solar subcell adjacent to the graded interlayer, the third subcell having a fourth band gap smaller than the second band gap such that the third subcell is lattice mismatched with respect to the second subcell. A lower fourth solar subcell is provided adjacent to the third subcell and lattice matched thereto, the lower fourth subcell having a fifth band gap smaller than the fourth band gap.

Abstract: A multijunction solar cell is fabricated according to an embodiment by providing a substrate, depositing a nucleation first layer over and directly in contact with the substrate, depositing a second layer containing an arsenic dopant over the nucleation layer and depositing a sequence of layers over the second layer forming at least one solar subcell. The nucleation layer serves as a diffusion barrier to the arsenic dopant such that diffusion of the arsenic dopant into the substrate is limited in depth by the nucleation layer.

Abstract: A method of forming a multijunction solar cell comprising an upper subcell, a middle subcell, and a lower subcell comprising providing a first substrate for the epitaxial growth of semiconductor material; forming a first solar subcell on said substrate having a first band gap; forming a second solar subcell over said first subcell having a second band gap smaller than said first band gap; and forming a grading interlayer over said second subcell having a third band gap larger than said second band gap forming a third solar subcell having a fourth band gap smaller than said second band gap such that said third subcell is lattice mismatched with respect to said second subcell.

Abstract: A multijunction solar cell including an upper first solar subcell having a first band gap; a second solar subcell adjacent to the first solar subcell and having a second band gap smaller than the first band gap; a graded interlayer adjacent to the second solar subcell; the first graded interlayer having a third band gap greater than the second band gap; and a third solar subcell adjacent to the graded interlayer, the third subcell having a fourth band gap smaller than the second band gap such that the third subcell is lattice mismatched with respect to the second subcell. A lower fourth solar subcell is provided adjacent to the third subcell and lattice matched thereto, the lower fourth subcell having a fifth band gap smaller than the fourth band gap.

Abstract: In a preferred embodiment, a layer of TiAu is placed in an etch in a solar cell with a contact at a doped layer of GaAs. Electric current is conducted through a diode and away from the main cell by passing through the contact point at the GaAs and traversing a lateral conduction layer. These means of activating, or “turning on” the diode, and passing the current through the circuit results in greater efficiencies than in prior art devices. The diode is created during the manufacture of the other layers of the cell and does not require additional manufacturing.

Abstract: A multijunction solar cell including first and second solar cells on a substrate with an integral bypass diode having an intrinsic layer and operative for passing current when the multijunction solar cell is shaded. In one embodiment, a vertical sequence of solar cells are epitaxially grown on a first portion of the substrate, and the layers of the diode are epitaxially grown on a second portion of the substrate with the layers of the bypass diode being deposited subsequent to the layers of the top solar cell.

Abstract: A system for the generation of electrical power from sunlight includes a solar cell assembly with at least two sets of solar cells, each of these sets being adapted to a set-specific light frequency spectrum so as to convert light having said set-specific frequency spectrum into electrical energy with an optimized energy conversion efficiency. The system is arranged to respond to changes in the frequency spectrum of the sunlight, for example, in accordance with the time of the day, by causing the sunlight to selectively impinge on one or another of the different sets of solar cells. Thus, an enhanced energy conversion efficiency of the system is obtained.

Abstract: A multijunction solar cell including an upper first solar subcell having a first band gap; a middle second solar subcell adjacent to the first solar subcell and having a second band gap smaller than the first band gap, and having a base layer and an emitter layer, a graded interlayer adjacent to the second solar subcell; the graded interlayer having a third band gap greater than said second band gap; a third solar subcell adjacent to the interlayer, the third subcell having a fourth band gap smaller than the second band gap such that the third subcell is lattice mismatched with respect to the second subcell; and a distributed Bragg reflector (DBR) adjacent the second or third subcell.

Abstract: A solar cell array including a first solar cell with an integral bypass diode and an adjacent second solar cell and two discrete metal interconnection members coupling the anode of the bypass diode of the first cell with the anode of the second solar cell.

Abstract: A method of forming a multijunction solar cell including an upper subcell, a middle subcell, and a lower subcell, including providing first substrate for the epitaxial growth of semiconductor material; forming a first solar subcell on the substrate having a first band gap; forming a second solar subcell over the first solar subcell having a second band gap smaller than the first band gap; forming a grading interlayer over the second subcell, the grading interlayer having a third band gap greater than the second band gap; and forming a third solar subcell over the grading interlayer having a fourth band gap smaller than the second band gap such that the third subcell is lattice mis-matched with respect to the second subcell, wherein at least one of the bases of a solar subcell has an exponentially doped profile.

Abstract: A method of forming a multijunction solar cell includes providing a substrate, forming a first subcell by depositing a nucleation layer over the substrate and a buffer layer including gallium arsenide (GaAs) over the nucleation layer, forming a middle second subcell having a heterojunction base and emitter disposed over the first subcell and forming first and second tunnel junction layers between the first and second subcells. The first tunnel junction layer includes GaAs over the first subcell and the second tunnel junction layer includes aluminum gallium arsenide (AlGaAs) over the first tunnel junction layer. The method further includes forming a third subcell having a homojunction base and emitter disposed over the middle subcell.

Abstract: The present application is directed to a multi-terminal semiconductor solar cell. The solar cell may be dual junction solar cells comprising single junctions independently interconnected by a middle lateral conduction layer (MLCL). The solar cells may include a GaAs subcell, a GaInP subcell, and a MLCL disposed therebetween. In addition, the solar cells may include a plurality of terminals. One terminal may be operatively connected to the GaAs subcell, a second terminal may be operatively connected to the GaInP subcell and a third terminal may be operatively connected to the MLCL.

Abstract: A method of forming a multijunction solar cell including an upper subcell, a middle subcell, and a lower subcell by providing a substrate for the epitaxial growth of semiconductor material; forming a first solar subcell on the substrate having a first band gap; forming a second solar subcell over the first solar subcell having a second band gap smaller than the first band gap; forming a graded interlayer over the second subcell, the graded interlayer having a third band gap greater than the second band gap; forming a third solar subcell over the graded interlayer having a fourth band gap smaller than the second band gap such that the third subcell is lattice mismatched with respect to the second subcell; and forming a contact layer over the third subcell having a fifth band gap greater than at least the magnitude of the second band gap.

Abstract: A system for generating electrical power from solar radiation utilizing a III-V compound multijunction semiconductor solar cell; a concentrator for focusing sunlight on the solar cell; and a heat spreader connected to the solar cell for cooling the cell. The solar cell is preferably an inverted metamorphic multijunction solar cell.

Abstract: Dopant diffusion into semiconductor material is controlled during fabrication of a semiconductor structure by depositing a nucleation layer over a first layer of the semiconductor structure and depositing a device layer containing the dopant over the nucleation layer. The nucleation layer serves as a diffusion barrier by limiting in depth the diffusion of the dopant into the first layer. The dopant can include arsenic (As).

Abstract: A method of forming a multijunction solar cell including an upper subcell, a middle subcell, and a lower subcell, the method including: providing a substrate for the epitaxial growth of semiconductor material; forming a first solar subcell on the substrate having a first band gap and including a pseudomorphic window layer; forming a second solar subcell over the first solar subcell having a second band gap smaller than the first band gap; forming a graded interlayer over the second subcell, the graded interlayer having a third band gap greater than the second band gap; and forming a third solar subcell over the graded interlayer having a fourth band gap smaller than the second band gap such that the third subcell is lattice mismatched with respect to the second solar subcell.

Abstract: A multijunction solar cell including an upper first solar subcell having a first band gap; a middle second solar subcell adjacent to the first solar subcell and having a second band gap smaller than the first band gap and having a base layer and an adjacent emitter layer, wherein the other layer adjacent to the emitter layer has an index of refraction substantially equal to that of the emitter layer; a graded interlayer adjacent to the second solar having a third band gap greater than said second band gap; and a lower solar subcell adjacent to the interlayer, and having a fourth band gap smaller than the second band gap, the third subcell being lattice mismatched with respect to the second subcell.

Abstract: A method of making a multijunction solar cell, including first and second solar cells on a substrate with a bypass diode having an intrinsic layer and operative for passing current when the multijunction solar cell is shaded. In one embodiment, a vertical sequence of solar cells are epitaxially grown on a first portion of the substrate, and the layers of the diode are epitaxially grown on a second portion of the substrate with the layers of the bypass diode being deposited subsequent to the layers of the top solar cell.