A layered OP material is provided that comprises an OPGaAs template, and a layer of GaP on the OPGaAs template. The OPGaAs template comprises a patterned layer of GaAs having alternating features of inverted crystallographic polarity of GaAs. The patterned layer of GaAs comprises a first feature comprising a first crystallographic polarity form of GaAs having a first dimension, and a second feature comprising a second crystallographic polarity form of GaAs having a second dimension. The layer of GaP on the patterned layer of GaAs comprises alternating regions of inverted crystallographic polarity that generally correspond to their underlying first and second features of the patterned layer of GaAs. Additionally, each of the alternating regions of inverted crystallographic polarity of GaP are present at about 100 micron thickness or more. A method of forming the OPGaP is also provided.

The disclosure provides a photo-detection device for use in long-wave infrared detection and a method of fabrication. The device comprises a GaSb substrate, a photo absorbing layer comprising InAs/InAsSb superlattice type-II, a barrier layer comprising AlAsSb, and a contact layer comprising InAs/InAsSb superlattice type-II. The barrier layer is configured to allow minority carrier holes current flow while blocking majority carrier electrons current flow between the photo-absorbing and contact layers. The disclosure further provides a method of producing the photo-detector using photolithography which includes selective etching of the contact layer that stops on the top of the barrier so no etching is made to the barrier layer so the barrier may operate as a passivator too. The disclosure presents an x-ray and photoluminescence results for InAs/InAsSb superlattice type-II material. Also present a measurement of a single element, Long-Wave photo-detector, showing very low dark current and very high Quantum efficiency, as predicted.

A method of manufacturing a photodiode including a useful layer made of a semi-conductor alloy. The useful layer has a band gap value which decreases from its upper face to its lower face. A step of producing a first doped region forming a PN junction with a second doped region of the useful layer, said production of a first doped region including a first doping step, so as to produce a base portion; and a second doping step, so as to produce at least one protuberance protruding from the base portion and in the direction of the lower face.

A photovoltaic device, particularly a solar cell, comprises an interface between a layer of Group III-V material and a layer of Group IV material with a thin silicon diffusion barrier provided at or near the interface. The silicon barrier controls the diffusion of Group V atoms into the Group IV material, which is doped n-type thereby. The n-type doped region can provide the p-n junction of a solar cell in the Group IV material with superior solar cell properties. It can also provide a tunnel diode in contact with a p-type region of the III-V material, which tunnel diode is also useful in solar cells.

The disclosure describes multi-junction solar cell structures that include two or more graded interlayers.

An alloy composition for a subcell of a solar cell is provided that has a bandgap of at least 0.9 eV, namely, Ga.sub.1-xIn.sub.xN.sub.yAs.sub.1-y-zSb.sub.z with a low antimony (Sb) content and with enhanced indium (In) content and enhanced nitrogen (N) content, achieving substantial lattice matching to GaAs and Ge substrates and providing both high short circuit currents and high open circuit voltages in GaInNAsSb subcells for multijunction solar cells. The composition ranges for Ga.sub.1-xIn.sub.xN.sub.yAs.sub.1-y-zSb.sub.z are 0.07x0.18, 0.025y0.04 and 0.001z0.03.

The disclosure describes multi-junction solar cell structures that include two or more graded interlayers.

A photovoltaic cell is provided that can be used under high levels of solar concentration (1000 suns). The present cell includes at least one junction produced on a substrate based on gallium antimonide, the at least one junction having two alloys based on an antimonide material (Ga.sub.1-xAl.sub.xAs.sub.ySb.sub.1-y) lattice-matched on the substrate GaSb. If there are several junctions, two neighbouring junctions are separated by a tunnel junction.

A multijunction solar cell and its method of manufacture including interconnected first and second discrete semiconductor regions disposed adjacent and parallel to each other in a single semiconductor body, including first top subcell, second (and possibly third) lattice matched middle 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 the interconnected regions form at least a four junction solar cell by a series connection being formed between the bottom solar subcell in the first semiconductor region and the bottom solar subcell in the second semiconductor region.

A multijunction solar cell assembly and its method of manufacture including first and second discrete and different semiconductor body subassemblies which are electrically interconnected to form a five junction solar cell, each semiconductor body subassembly including first, second, third and fourth lattice matched subcells; wherein the average band gap of all four cells in each subassembly is greater than 1.44 eV.