Abstract: A photovoltaic solar cell for producing energy from the sun including a germanium substrate including a first photoactive junction and forming a bottom solar subcell; a gallium arsenide middle cell disposed on said substrate; an indium gallium phosphide top cell disposed over the middle cell; and a surface grid including a plurality of spaced apart grid lines, wherein the grid lines have a thickness greater than 7 microns, and each grid line has a cross-section in the shape of a trapezoid with a cross-sectional area between 45 and 55 square microns.

Abstract: A photovoltaic solar cell for producing energy from the sun including a germanium substrate including a first photoactive junction and forming a bottom solar subcell; a gallium arsenide middle cell disposed on said substrate; an indium gallium phosphide top cell disposed over the middle cell; and a surface grid including a plurality of spaced apart grid lines, wherein the grid lines have a thickness greater than 7 microns, and each grid line has a cross-section in the shape of a trapezoid with a cross-sectional area between 45 and 55 square microns.

Abstract: A III-V compound semiconductor structure comprises epitaxial structures that include an integrated pair of different types of active devices. The semiconductor structure includes a semi-insulating substrate of a compound semiconductor III-V material and a first compound semiconductor III-V epitaxial structure disposed on the substrate. A concentration profile of dopant material in the semiconductor structure decreases substantially smoothly across an interface between the substrate and the first epitaxial structure in a direction from the first epitaxial structure toward the substrate, and continues to decrease substantially smoothly from the interface with increasing depth into the substrate despite the presence of silicon or oxygen contaminant at the interface. The interface is substantially free of a second contaminant that was present, during formation of the first epitaxial structure, in a chamber in which the first epitaxial structure was formed.

Abstract: A method of fabricating an integrated circuit on a compound semiconductor III-V wafer including at least two different types of active devices by providing a substrate; growing a first epitaxial structure on the substrate; growing a second epitaxial structure on the first epitaxial structure; and processing the epitaxial structures to form different types of active devices, such as HBTs and FETs.

Abstract: An integrated pair of HBT and FET transistors shares a common compound semiconductor III-V epitaxial layer. The integrated pair of transistors includes a semi-insulating substrate of a compound semiconductor III-V material, a first epitaxial structure disposed on top of the substrate, a second epitaxial structure on top of the first epitaxial structure, and a third epitaxial structure disposed on top of the second epitaxial structure. The first epitaxial structure forms a portion of the HBT transistor. A concentration profile of a first contaminant, which contributes electrical charge, decreases substantially smoothly across an interface between the semi-insulating substrate and the first epitaxial structure. In some cases, the interface is free of a second contaminant that was present, during formation of the epitaxial structures, in a chamber in which the epitaxial structures were formed.

Abstract: According to an embodiment, a solar cell receiver for converting solar energy to electricity includes a ceramic substrate, a solar cell and a heat sink. The ceramic substrate has a first metallized surface and an opposing second metallized surface. The first metallized surface of the ceramic substrate has separated conductive regions. The solar cell has a conductive first surface connected to a first one of the conductive regions of the ceramic substrate and an opposing second surface having a conductive contact area connected to a second one of the conductive regions. The heat sink is bonded to the second metallized surface of the ceramic substrate with a thermally conductive attach media, such as a metal-filled epoxy adhesive or solder.

Abstract: A method of fabricating an integrated circuit on a compound semiconductor III-V wafer including at least two different types of active devices by providing a substrate; growing a first epitaxial structure on the substrate; growing a second epitaxial structure on the first epitaxial structure; and processing the epitaxial structures to form different types of active devices, such as HBTs and FETs.

Abstract: A method of fabricating an epitaxial compound semiconductor III-V wafer suitable for the subsequent fabrication of at least two different types of integrated active devices (such as an HBT and a FET) on such wafer by providing a substrate; growing a first epitaxial structure on the substrate; and growing a second epitaxial structure on the first epitaxial structure.

Abstract: A hydrogen passivated photovoltaic device such as a solar cell comprises a lattice mismatched substrate such as Ge or Si, and a hydrogen passivated heteroepitaxial layer such as InP grown on the substrate. The hydrogen passivated heteroepitaxial III-V photovoltaic device is produced by exposing a sample of a heteroepitaxial III-V material grown on a lattice-mismatched substrate to reactive hydrogen species at elevated temperatures. Reactive hydrogen forms bonds with dangling bonds along dislocations defined in the sample. The electrical activity in the dislocations is passivated as a result of the hydrogenation process.