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 present disclosure provides methods of fabricating a multijunction solar cell panel in which one or more of the steps are performed using an automated process. In some embodiments, the automated process uses machine vision.

A tandem solar cell includes a substrate a plurality of sub-cells stacked on the substrate and configured to sequentially perform photoelectric conversion with different wavelength band, and a metal disk array disposed on at least one of interfaces between adjacent sub-cells. A center wavelength of wavelength bands corresponding to the sub-cells gradually decreases as progressing downward with respect to an uppermost layer. The metal disk array reflects a light transmitting a sub-cell disposed over the metal disk array without being absorbed therein. The metal disk array is inserted by means of wafer bonding.

Manufacture of multi-junction solar cells, and devices thereof, are disclosed. The architectures are also adapted to provide for a more uniform and consistent fabrication of the solar cell structures, leading to improved yields, greater efficiency, and lower costs. Certain solar cells may be from a different manufacturing process and further include one or more compositional gradients of one or more semiconductor elements in one or more semiconductor layers, resulting in a more optimal solar cell device. A multi-junction cell may include a back surface field layer, a tunneling junction layer, a first active cell, and a second active cell.

A multijunction tandem photovoltaic device is disclosed having a bottom subcell of silicon germanium or silicon germanium tin material and above that a subcell of gallium nitride arsenide bismide, or indium gallium nitride arsenide bismide, material. The materials are lattice matched to gallium arsenide, which preferably forms the substrate. Preferably, further lattice matched subcells of gallium arsenide, indium gallium phosphide and aluminum gallium arsenide or aluminum indium gallium phosphide are provided.

The present disclosure provides a multijunction solar cell comprising: an upper solar subcell having an indirect band gap semiconductor emitter layer composed of greater than 0.8 but less than 1.0 mole fraction aluminum and a base layer, the emitter layer and the base layer forming a heterojunction solar subcell; and a lower solar subcell disposed beneath the upper solar subcell, wherein the lower solar subcell has an emitter layer and a base layer forming a photoelectric junction. In some embodiments, the emitter layer of the upper solar subcell is an n-type Al.sub.xGa.sub.1-xAs layer with 0.8<x<1.0 and having a band gap of greater than 2.0 eV.

A solar cell fabricated from a semiconductor growth substrate; that is sub sequentially removed a sequence of layers of semiconductor material grown on the semiconductor growth substrate forming the solar cell; a metal contact layer deposited over the sequence of layers; of a permanent supporting substrate being affixed directly over the metal contact layer and permanently bonded thereto.

A method of manufacturing a solar cell comprising providing a first semiconductor substrate with an epitaxial sequence of layers of semiconductor material forming a solar cell deposited over the first semiconductor substrate using an MOCVD reactor; depositing a metal layer on top of the sequence of layers of semiconductor material, the metal layer including a top surface layer composed of gold or silver; providing a polymer film; depositing a first metallic adhesion layer that has a coefficient of thermal expansion substantially different from that of the top surface layer on one surface of the polymer film; depositing a second metal adhesion layer over the first metallic adhesion layer and having a different composition from the first layer and having no chemical elements in common; and adjoining the second adhesion layer of the polymer film to the metal layer of the sequence of layers and permanently bonding it thereto by a thermocompressive diffusion bonding technique.

A Group III-V compound semiconductor solar cell includes a buffer layer (108) and a first cell (131) both between a first electrode (121) and a second electrode (102). The buffer layer (108) has a portion in which first segments (141a, 142a, 143a, 144a) and second segments (141b, 142b, 143b, 144b) are alternately provided. Each of the first segments has a Group III element composition that continuously changes with an increasing thickness of the buffer layer (108) as traced from a side located opposite where the first cell (131) is disposed toward a side where the first cell (131) is disposed. Each of the second segments has a Group III element composition that changes without an increase in the thickness of the buffer layer (108).

A semiconductor device structure having increased photogenerated current density, and increased current output is disclosed. The device includes low bandgap absorber regions that increase the range of wavelengths at which photogeneration of charge carriers takes place, and for which useful current can be collected. The low bandgap absorber regions may be strain balanced by strain-compensation regions, and the low bandgap absorber regions and strain-compensation regions may be formed from the same ternary semiconductor family. The device may be a solar cell, subcell, or other optoelectronic device with a metamorphic or lattice-mismatched base layer, for which the low bandgap absorber region improves the effective bandgap combination of subcells and current balance within the multijunction cell, for higher efficiency conversion of the solar spectrum.