Abstract: A photocathode. The photocathode includes an absorber. The absorber a p-type bulk active layer and a plurality of nanostructures formed on the p-type bulk active layer. The Photocathode further includes the plurality of nanostructures, such that the plurality of nanostructures are formed at a band bending region between the bulk active layer and the vacuum.

Abstract: A photocathode epitaxial structure. The photocathode epitaxial structure includes a binary compound substrate material. The photocathode epitaxial structure further includes an active device absorber layer forming a portion of a p-type device photocathode formed on the binary compound substrate material. The active device absorber layer comprising at least a quaternary or greater material structure configured to be lattice matched with the substrate material to reduce strain to allow charge carriers to go further in the active device absorber layer implemented in the photocathode of a nightvision system.

Abstract: A photocathode epitaxial structure. The photocathode epitaxial structure includes an improved substrate stack. The improved substrate stack includes a GaAs substrate and one or more additional layers formed on the GaAs substrate. The one or more additional layers are configured to provide an improved substrate stack surface with predetermined characteristics for forming a semiconductor device on the improved substrate stack surface. The photocathode epitaxial structure further includes an InGaAs p-type photocathode formed on the improved substrate stack surface. The InGaAs p-type photocathode has a predetermined percentage of In.

Abstract: A multijunction solar cell and its method of fabrication, including an upper and a lower solar subcell each having an emitter layer and a base layer forming a photoelectric junction; a near infrared (NIR) wideband reflector layer disposed below the upper subcell and above the lower subcell for reflecting light in the spectral range of 900 to 1050 nm which represents unused and undesired solar energy and thereby reducing the overall solar energy absorptance in the solar cell and providing thermodynamic radiative cooling of the solar cell when deployed in space outside the atmosphere.

Abstract: A multijunction solar cell and its method of fabrication, including an upper and a lower solar subcell each having an emitter layer and a base layer forming a photoelectric junction; a near infrared (NIR) wideband reflector layer disposed below the upper subcell and above the lower subcell for reflecting light in the spectral range of 900 to 1050 nm which represents unused and undesired solar energy and thereby reducing the overall solar energy absorptance in the solar cell and providing thermodynamic radiative cooling of the solar cell when deployed in space outside the atmosphere.

Abstract: A multijunction solar cell and its method of fabrication, including an upper and a lower solar subcell each having an emitter layer and a base layer forming a photoelectric junction; a near infrared (NIR) wideband reflector layer disposed below the upper subcell and above the lower subcell for reflecting light in the spectral range of 900 to 1050 nm which represents unused and undesired solar energy and thereby reducing the overall solar energy absorptance in the solar cell and providing thermodynamic radiative cooling of the solar cell when deployed in space outside the atmosphere.

Abstract: Stacked edge-emitting lasers having multiple active regions coupled together using tunnel junctions. The composition of each of the active regions (quantum wells and/or barriers) differs to provide a controlled different emission wavelength for each junction, when each junction is individually operated at the same fixed temperature. When the device is under operation, a thermal gradient exists across the junctions, and the emission wavelengths of each junction coincide as the different temperature for each junction causes relative wavelength shifts. Thus, the effect of temperature on the emission wavelength of the device is compensated for, producing a narrower linewidth emission.

Abstract: A multijunction solar cell including a substrate and at least one solar subcell having an emitter layer, a base layer, and a window layer adjacent to the emitter layer composed of a semiconductor window material, wherein the window material has a graded composition such that the material at the interface between the top surface of the emitter layer of the at least one solar subcell and the bottom surface of the window layer has a compression as measured by a delta in the Bragg angle from the substrate in a range of 0 to 500 arcseconds in compression, and material at the top surface of the window layer has a tension as measured by a delta in the Bragg angle from the substrate in a range of 50 to 700 arcseconds in tension, wherein the delta in the Bragg angle is obtained from a rocking curve from a triple axis coupled scan of ? and 2? (omega-2theta) using 1.5406 ? radiation.

Abstract: 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 0.7 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 AlxGa1-xAs layer with 0.7<x<1.0 and having a band gap of greater than 1.85 eV.

Abstract: A multijunction solar cell and its method of fabrication, including an upper and a lower solar subcell each having an emitter layer and a base layer forming a photoelectric junction; a near infrared (NIR) wideband reflector layer disposed below the upper subcell and above the lower subcell for reflecting light in the spectral range of 900 to 1050 nm which represents unused and undesired solar energy and thereby reducing the overall solar energy absorptance in the solar cell and providing thermodynamic radiative cooling of the solar cell when deployed in space outside the atmosphere.

Abstract: 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 AlxGa1-xAs layer with 0.8<x<1.0 and having a band gap of greater than 2.0 eV.

Abstract: A multijunction solar cell and its method of fabrication, including an upper and a lower solar subcell each having an emitter layer and a base layer forming a photoelectric junction; a near infrared (NIR) wideband reflector layer disposed below the upper subcell and above the lower subcell for reflecting light in the spectral range of 900 to 1050 nm which represents unused and undesired solar energy and thereby reducing the overall solar energy absorptance in the solar cell and providing thermodynamic radiative cooling of the solar cell when deployed in space outside the atmosphere.

Abstract: A multijunction solar cell which includes: an upper first solar subcell having a first band gap; a second solar subcell adjacent to said upper first solar subcell and having a second band gap smaller than said first band gap; a third solar subcell adjacent to said second solar subcell and having a third band gap smaller than said second band gap; a graded interlayer adjacent to said third solar subcell, said graded interlayer having a fourth band gap greater than said third band gap; and at least a fourth solar subcell adjacent to said graded interlayer, said fourth solar subcell having a fifth band gap smaller than said third band gap such that said lower fourth solar subcell is lattice mismatched with respect to said third solar subcell.