Abstract: A method for fabricating an upright photovoltaic cell comprises growing one or more epitaxial layers on a substrate, thereby forming a diffused active junction on the substrate and one more additional active junctions above the diffused active junction. The method further comprises selectively etching an areal region of the one or more epitaxial layers, thereby forming a mesa on the substrate and exposing a substrate-contact region parallel to the areal region at a base of the mesa. The method further comprises depositing contact material onto the substrate-contact region, to form the first contact, and concertedly onto a mesa-contact region of the mesa, to form the second contact.

Abstract: A solar cell optimized for performance at high radiation doses, wherein the solar cell includes: a sub-cell comprised of a base and an emitter; the base of the sub-cell has a thickness of about 2 to 3 ?m; the base of the sub-cell is doped at about 1e14 cm?3 to 1e16 cm?3; and a reflector is inserted behind the sub-cell to maximize current generated by the sub-cell.

Abstract: A solar cell design includes fabricating one or more gridlines for extracting photo-current on a front surface of the solar cell, wherein each of the gridlines is a metal grid and a cap layer, and at least a portion of the metal grid is deposited on the cap layer; and controlling an alignment of the metal grid relative to the cap layer, and a width of the cap layer relative to a width of the metal grid, so that a minimum cap edge offset distance value is about 1 ?m or more. The alignment of the metal grid relative to the cap layer and the width of the cap layer relative to the width of the metal grid are controlled at areas on the front surface of the solar cell opposite where welding occurs on a back-side of the solar cell. The alignments and widths of the metal grid relative to the cap layer are controlled by a photomask.

Abstract: An interconnect for making electrical connections for a solar cell, wherein the interconnect consists of a single toe, without a second toe connected to the single toe, and with no connected crossbars. A plurality of the interconnects may be placed uniformly across an edge of the solar cell. In one example, three interconnects are placed uniformly across an edge of the solar cell, when the solar cell has an area less than 60 cm2. In another example, four or more interconnects are placed uniformly across an edge of the solar cell, when the solar cell has an area greater than 60 cm2.

Abstract: A quantum efficiency test controller (QETC) and related techniques for measuring quantum efficiency are described. The QETC performs one or more test iterations to obtain test results regarding quantum efficiency of a multijunction photovoltaic device (MPD) having a number N of photovoltaic junctions (N>0), where the QETC is associated with N bias light sources. During a test iteration, the QETC activates a grating monochromator to emit a first test probe of monochromatic light at a first wavelength; and while the grating monochromator is emitting the first test probe, iterates through and activates each of the N bias light sources to emit a corresponding bias band of wavelengths of light. After performing the test iteration(s), the QETC generates an output that is based on the test results related to the quantum efficiency of the MPD.

Abstract: The present disclosure generally relates to a solar cell device that includes a substrate comprising a front side surface and a backside surface; an epitaxial region overlying the substrate, wherein the epitaxial region comprises a first Bragg reflector disposed below a first solar cell, wherein the first solar cell has a first bandgap, wherein the first Bragg reflector is operable to reflect a first range of radiation wavelengths back into the first solar cell, and is operable to cool the solar cell device by reflecting a second range of radiation wavelengths that are outside the photogeneration wavelength range of the first solar cell or that are weakly absorbed by the first solar cell, and may additionally comprise a second Bragg reflector operable to reflect a third range of radiation wavelengths back into the first solar cell.

Abstract: A quantum efficiency test controller (QETC) and related techniques for measuring quantum efficiency are described. The QETC performs one or more test iterations to obtain test results regarding quantum efficiency of a multijunction photovoltaic device (MPD) having a number N of photovoltaic junctions (N>0), where the QETC is associated with N bias light sources. During a test iteration, the QETC activates a grating monochromator to emit a first test probe of monochromatic light at a first wavelength; and while the grating monochromator is emitting the first test probe, iterates through and activates each of the N bias light sources to emit a corresponding bias band of wavelengths of light. After performing the test iteration(s), the QETC generates an output that is based on the test results related to the quantum efficiency of the MPD.

Abstract: Systems, methods, and apparatus for light collection and conversion to electricity are disclosed herein. The disclosed method involves receiving, by at least one concentrating element (e.g., a lens), light from at least one light source, where the light comprises direct light and diffuse light. The method further involves focusing, by at least one concentrating element, the direct light onto at least one concentrator photovoltaic cell. Also, the method involves passing, by at least one concentrating element, the diffuse light onto at least one solar cell of an array of solar cells arranged on a flat plate, where at least one concentrator photovoltaic cell is bonded on top of at least one of the solar cells in the array. In addition, the method involves collecting, by at least one concentrator photovoltaic cell, the direct light. Further, the method involves collecting, by at least one solar cell, the diffuse light.

Abstract: An apparatus and methods for compensating for spatial non-uniformities in solar simulators. This is accomplished in part by acquiring a spatial map of the intensity distribution that the solar simulator produces across the illumination plane using a reference cell, identifying an area of an arbitrary solar cell within the illuminated area, and then calculating the expected illumination levels for that solar cell in that specific location based on the spatial mapping. The results of that process can then be used to determine the efficiency of the arbitrary solar cell during a test in which the reference cell (of known efficiency), located in a different part of the illuminating beam, simultaneously measures the illumination in one area of the illumination beam.

Abstract: The present disclosure generally relates to a solar cell device that a first Bragg reflector disposed below a first solar cell and a second Bragg reflector disposed below the first Bragg reflector, wherein the first solar cell comprises a dilute nitride composition and has a first bandgap, wherein the first Bragg reflector is operable to reflect a first range of radiation wavelengths back into the first solar cell and the second Bragg reflector is operable to reflect a third range of wavelengths back into the first solar cell, and the first Bragg reflector and the second Bragg reflector are operable to cool the solar cell device by reflecting a second range of radiation wavelengths that are outside the photogeneration wavelength range of the first solar cell or that are weakly absorbed by the first solar cell.

Abstract: The present disclosure generally relates to a solar cell device that includes a substrate comprising a front side surface and a backside surface; an epitaxial region overlying the substrate, wherein the epitaxial region comprises a first Bragg reflector disposed below a first solar cell, wherein the first solar cell has a first bandgap, wherein the first Bragg reflector is operable to reflect a first range of radiation wavelengths back into the first solar cell, and is operable to cool the solar cell device by reflecting a second range of radiation wavelengths that are outside the photogeneration wavelength range of the first solar cell or that are weakly absorbed by the first solar cell, and may additionally comprise a second Bragg reflector operable to reflect a third range of radiation wavelengths back into the first solar cell.

Abstract: The present disclosure generally relates to a solar cell device that a first Bragg reflector disposed below a first solar cell and a second Bragg reflector disposed below the first Bragg reflector, wherein the first solar cell comprises a dilute nitride composition and has a first bandgap, wherein the first Bragg reflector is operable to reflect a first range of radiation wavelengths back into the first solar cell and the second Bragg reflector is operable to reflect a third range of wavelengths back into the first solar cell, and the first Bragg reflector and the second Bragg reflector are operable to cool the solar cell device by reflecting a second range of radiation wavelengths that are outside the photogeneration wavelength range of the first solar cell or that are weakly absorbed by the first solar cell.

Abstract: An apparatus and methods for retrofitting known solar simulator systems to allow the exit beam to be changed in size and location without changing the other fundamental functions of the main optical elements. The solar simulator system is provided with means for de-magnifying the exit beam to provide higher power densities at the illumination plane. By adding or replacing one final optical element, the system user can change the location of the illumination plane and the size of the illumination area. This change in size can increase or decrease the power density of the exit beam.

Abstract: An apparatus and methods for compensating for spatial non-uniformities in solar simulators. This is accomplished in part by acquiring a spatial map of the intensity distribution that the solar simulator produces across the illumination plane using a reference cell, identifying an area of an arbitrary solar cell within the illuminated area, and then calculating the expected illumination levels for that solar cell in that specific location based on the spatial mapping. The results of that process can then be used to determine the efficiency of the arbitrary solar cell during a test in which the reference cell (of known efficiency), located in a different part of the illuminating beam, simultaneously measures the illumination in one area of the illumination beam.

Abstract: A tunnel junction for a semiconductor device is disclosed. The tunnel junction includes a n-doped tunnel layer and a p-doped tunnel layer. The p-doped tunnel layer is constructed of aluminum gallium arsenide antimonide (AlGaAsSb). A semiconductor device including the tunnel junction with the p-doped tunnel layer constructed of AlGaAsSb is also disclosed.

Abstract: Systems, methods, and apparatus for light collection and conversion to electricity are disclosed herein. The disclosed method involves receiving, by at least one concentrating element (e.g., a lens), light from at least one light source, where the light comprises direct light and diffuse light. The method further involves focusing, by at least one concentrating element, the direct light onto at least one concentrator photovoltaic cell. Also, the method involves passing, by at least one concentrating element, the diffuse light onto at least one solar cell of an array of solar cells arranged on a flat plate, where at least one concentrator photovoltaic cell is bonded on top of at least one of the solar cells in the array. In addition, the method involves collecting, by at least one concentrator photovoltaic cell, the direct light. Further, the method involves collecting, by at least one solar cell, the diffuse light.

Abstract: An apparatus and methods for retrofitting known solar simulator systems to allow the exit beam to be changed in size and location without changing the other fundamental functions of the main optical elements. The solar simulator system is provided with means for de-magnifying the exit beam to provide higher power densities at the illumination plane. By adding or replacing one final optical element, the system user can change the location of the illumination plane and the size of the illumination area. This change in size can increase or decrease the power density of the exit beam.

Abstract: A method of fabricating on a semiconductor substrate bifacial tandem solar cells with semiconductor subcells having a lower bandgap than the substrate bandgap on one side of the substrate and with subcells having a higher bandgap than the substrate on the other including, first, growing a lower bandgap subcell on one substrate side that uses only the same periodic table group V material in the dislocation-reducing grading layers and bottom subcells as is present in the substrate and after the initial growth is complete and then flipping the substrate and growing the higher bandgap subcells on the opposite substrate side which can be of different group V material.

Abstract: A method of fabricating on a semiconductor substrate bifacial tandem solar cells with semiconductor subcells having a lower bandgap than the substrate bandgap on one side of the substrate and with subcells having a higher bandgap than the substrate on the other including, first, growing a lower bandgap subcell on one substrate side that uses only the same periodic table group V material in the dislocation-reducing grading layers and bottom subcells as is present in the substrate and after the initial growth is complete and then flipping the substrate and growing the higher bandgap subcells on the opposite substrate side which can be of different group V material.

Abstract: A method of fabricating on a semiconductor substrate bifacial tandem solar cells with semiconductor subcells having a lower bandgap than the substrate bandgap on one side of the substrate and with subcells having a higher bandgap than the substrate on the other including, first, growing a lower bandgap subcell on one substrate side that uses only the same periodic table group V material in the dislocation-reducing grading layers and bottom subcells as is present in the substrate and after the initial growth is complete and then flipping the substrate and growing the higher bandgap subcells on the opposite substrate side which can be of different group V material.