Abstract: A method of forming a semiconductor structure including a multijunction solar cell with an upper subcell, a middle subcell, and a lower subcell, by providing 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. A bypass diode is further provided in the semiconductor structure with a region of first polarity of the solar cell connected with a region of second polarity of the bypass diode.

Abstract: A solar cell includes a semiconductor substrate and a sequence of semiconductor layers disposed over the substrate. The sequence of semiconductor layers includes a semiconductor window layer. The solar cell also includes a semiconductor silicon-containing cap layer over the window layer. The cap layer is spatially separated from the window layer by a semiconductor barrier layer that either includes no silicon or has a silicon concentration that is significantly lower than the silicon concentration of the cap layer.

Abstract: Apparatus and Method for Optimizing the Efficiency of Germanium Junctions in Multi-Junction Solar Cells. In a preferred embodiment, an indium gallium phosphide (InGaP) nucleation layer is disposed between the germanium (Ge) substrate and the overlying dual-junction epilayers for controlling the diffusion depth of the n-doping in the germanium junction. Specifically, by acting as a diffusion barrier to arsenic (As) contained in the overlying epilayers and as a source of n-type dopant for forming the germanium junction, the nucleation layer enables the growth time and temperature in the epilayer device process to be minimized without compromising the integrity of the dual-junction epilayer structure. This in turn allows the arsenic diffusion into the germanium substrate to be optimally controlled by varying the thickness of the nucleation layer.

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, including a concave trough-shaped reflector; and a heat spreader connected to the solar cell for cooling the cell.

Abstract: A solar cell having a multijunction solar cell structure with a bypass diode is disclosed. The bypass diode provides a reverse bias protection for the multijunction solar cell structure. In one embodiment, the multifunction solar cell structure includes a substrate, a bottom cell, a middle cell, a top cell, a bypass diode, a lateral conduction layer, and a shunt. The lateral conduction layer is deposited over the top cell. The bypass diode is deposited over the lateral conduction layer. One side of the shunt is connected to the substrate and another side of the shunt is connected to the lateral conduction layer. In another embodiment, the bypass diode contains an i-layer to enhance the diode performance.

Abstract: A solar cell having a multifunction solar cell structure with a bypass diode is disclosed. The bypass diode provides a reverse bias protection for the multijunction solar cell structure. In one embodiment, the multifunction solar cell structure includes a substrate, a bottom cell, a middle cell, a top cell, a bypass diode, a lateral conduction layer, and a shunt. The lateral conduction layer is deposited over the top cell. The bypass diode is deposited over the lateral conduction layer. One side of the shunt is connected to the substrate and another side of the shunt is connected to the lateral conduction layer. In another embodiment, the bypass diode contains an i-layer to enhance the diode performance.

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: 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 solar cell having a multijunction solar cell structure with a bypass diode is disclosed. The bypass diode provides a reverse bias protection for the multijunction solar cell structure. In one embodiment, the multifunction solar cell structure includes a substrate, a bottom cell, a middle cell, a top cell, a bypass diode, a lateral conduction layer, and a shunt. The lateral conduction layer is deposited over the top cell. The bypass diode is deposited over the lateral conduction layer. One side of the shunt is connected to the substrate and another side of the shunt is connected to the lateral conduction layer. In another embodiment, the bypass diode contains an i-layer to enhance the diode performance.

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: TBHy is demonstrated as an efficient and a less carbon-containing N precursor for the growth of high-quality InGaAsN by MOCVD at lower growth temperatures. The photovoltaic characteristics of 1.20 eV InGaAsN solar cells, such as open-circuit voltage, short-circuit current, fill factor and efficiency are improved significantly by using TBHy compared to using DMHy. This demonstration can also be applied to other InGaAsN-based optoelectronic and electronic devices. Therefore, this invention is extremely important to expedite the demonstration of next-generation prototype products such as 1.3 &mgr;m-InGaAsN-epitaxial VCSELs for high-speed optical communications, low-power Npn InGaP/InGaAsN/GaAs HBTs and InGaP/AlGaAs/InGaAsN HEMTs for wireless applications, and high-efficiency multiple-junction InGaP/GaAs/InGaAsN/Ge solar cells for space power systems.

Abstract: Apparatus and Method for Optimizing the Efficiency of Germanium Junctions in Multi-Junction Solar Cells. In a preferred embodiment, an indium gallium phosphide (InGaP) nucleation layer is disposed between the germanium (Ge) substrate and the overlying dual-junction epilayers for controlling the diffusion depth of the n-doping in the germanium junction. Specifically, by acting as a diffusion barrier to arsenic (As) contained in the overlying epilayers and as a source of n-type dopant for forming the germanium junction, the nucleation layer enables the growth time and temperature in the epilayer device process to be minimized without compromising the integrity of the dual-junction epilayer structure. This in turn allows the arsenic diffusion into the germanium substrate to be optimally controlled by varying the thickness of the nucleation layer.