The present disclosure relates to a composition that includes a III-V planar substrate having a surface aligned with and parallel to a reference plane, where the surface includes a plurality of terraces, each terrace includes a first surface positioned between a first boundary and a second boundary, each boundary is substantially parallel to the other boundaries and positioned substantially parallel to the reference plane, and each terrace is separated from an adjacent terrace by a second surface positioned between the second boundary of the terrace and the first boundary of the adjacent terrace.

The present disclosure relates to a composition that includes a III-V planar substrate having a surface aligned with and parallel to a reference plane, where the surface includes a plurality of terraces, each terrace includes a first surface positioned between a first boundary and a second boundary, each boundary is substantially parallel to the other boundaries and positioned substantially parallel to the reference plane, and each terrace is separated from an adjacent terrace by a second surface positioned between the second boundary of the terrace and the first boundary of the adjacent terrace.

Tunnel junctions for multijunction solar cells are provided. According to an aspect of the invention, a tunnel junction includes a first layer including p-type AlGaAs, a second layer including n-type GaAs, wherein the second layer is a quantum well, and a third layer including n-type AlGaAs or n-type lattice matched AlGaInP. The quantum well can be GaAs or AlxGaAs with x being more than about 40%, and lattice matched GaInAsNSb in the Eg range of from about 0.8 to about 1.4 eV.

Tunnel junctions for multijunction solar cells are provided. According to an aspect of the invention, a tunnel junction includes a first layer including p-type AlGaAs, a second layer including n-type GaAs, wherein the second layer is a quantum well, and a third layer including n-type AlGaAs or n-type lattice matched AlGaInP. The quantum well can be GaAs or AlxGaAs with x being more than about 40%, and lattice matched GaInAsNSb in the Eg range of from about 0.8 to about 1.4 eV.

A multijunction solar cell including interconnected first and second discrete semiconductor regions disposed adjacent and parallel to each other including first top solar subcell, second (and possibly third) lattice matched middle solar subcells; a graded interlayer adjacent to the last middle solar subcell; and a bottom solar subcell adjacent to said graded interlayer being lattice mismatched with respect to the last middle solar subcell; wherein an opening is provided from the bottom side of the semiconductor body to one or more of the solar subcells so as to allow a discrete electrical connector to be made extending in free space and to electrically connect contact pads on one or more of the solar subcells.

A multijunction solar cell including interconnected first and second discrete semiconductor regions disposed adjacent and parallel to each other including first top solar subcell, second (and possibly third) lattice matched middle solar subcells; a graded interlayer adjacent to the last middle solar subcell; and a bottom solar subcell adjacent to said graded interlayer being lattice mismatched with respect to the last middle solar subcell; wherein an opening is provided from the bottom side of the semiconductor body to one or more of the solar subcells so as to allow a discrete electrical connector to be made extending in free space and to electrically connect contact pads on one or more of the solar subcells.

The present invention relates to the epitaxial lift-off of thin-films allowing the reuse of the expensive semiconductor substrates. In particular, it describes a structure and a method for epitaxial lift-off of several thin films from a single substrate (100) using a plurality of dissimilar sacrificial layers (101), strained layers (102, 104), and/or device or component layers (103). The properties of the sacrificial layers (101) and the strained layers (102,104) can be used (i) to facilitate the lift off process, (ii) to control the point of time of release of each released thin film individually and (iii) to aid in separation and sorting of the released thin films. The released device or component layers can comprise various useful structures, such as optoelectronic devices photonic components.

A multijunction solar cell including a substrate and a top (or light-facing) solar subcell having an emitter layer, a base layer, and a window layer adjacent to the emitter layer, the window layer composed of a material that is optically transparent, has a band gap of greater than 2.6 eV, and includes an appropriately arranged multilayer antireflection coating on the top surface thereof.

A multijunction solar cell including a substrate and a top (or light-facing) solar subcell having an emitter layer, a base layer, and a window layer adjacent to the emitter layer, the window layer composed of a material that is optically transparent, has a band gap of greater than 2.6 eV, and includes an appropriately arranged multilayer antireflection coating on the top surface thereof.

A multijunction solar cell including an upper first solar subcell having a first band gap and positioned for receiving an incoming light beam; and a second solar subcell disposed below and adjacent to and lattice matched with said upper first solar subcell, and having a second band gap smaller than said first band gap; wherein at least one of the solar subcells has a graded band gap throughout the thickness of at least a portion of its emitter layer and base layer.