Abstract: Zinc oxide compositions and methods for controlling zinc oxide particle size for sunscreen applications are provided herein. A method includes manipulating the size of multiple zinc oxide particles to be below a maximum threshold; selecting one or more media to be used in a sunscreen composition, wherein said selecting is based on the refractive index of each of the media; and integrating the manipulated zinc oxide particles into the selected media to create the sunscreen composition. A composition includes multiple zinc oxide particles, wherein each of the zinc oxide particles is (i) coated with an optical coating material and (ii) of a size that is below a maximum threshold; and a medium layer within which the zinc oxide particles are suspended, wherein the medium layer comprises a mixture of one or more media, and wherein each of the media has a refractive index below a predetermined threshold.

Abstract: Zinc oxide compositions as well as techniques for doping ZnO particles for sunscreen applications are provided herein. A method includes selecting one or more dopants to be incorporated into one or more zinc oxide particles in a sunscreen composition, wherein the one or more dopants comprise chromium, cobalt, gallium, and/or tin, and wherein said selecting is based on one or more optical properties associated with each of the dopants, and incorporating the selected dopants into the zinc oxide particles to create the sunscreen composition. A composition includes multiple zinc oxide particles suspended within a medium forming sunscreen composition, and one or more dopants incorporated into each of the multiple zinc oxide particles, wherein the one or more dopants comprise chromium, cobalt, gallium, and/or tin, and wherein each of the dopants imparts one or more optical properties to the zinc oxide particle within which the dopant is incorporated.

Abstract: A solar cell includes a p-type semiconductor substrate including a plurality of thin absorption regions and a plurality of thick absorption regions. The plurality of thin absorption regions and the plurality of thick absorption regions are coplanar on a bottom side thereof. An n-type semiconductor layer is disposed over a top side of the p-type semiconductor substrate. The n-type semiconductor layer has a substantially uniform thickness. Metallurgy is disposed on top of the n-type semiconductor layer. The plurality of thin absorption regions are sufficiently thin to render the semiconductor substrate flexible.

Abstract: Embodiments of this invention provide a method to fabricate an electrical contact. The method includes providing a substrate of a compound Group III-V semiconductor material having at least one electrically conducting doped region adjacent to a surface of the substrate. The method further includes fabricating the electrical contact to the at least one electrically conducting doped region by depositing a single crystal layer of germanium over the surface of the substrate so as to at least partially overlie the at least one electrically conducting doped region, converting the single crystal layer of germanium into a layer of amorphous germanium by implanting a dopant, forming a metal layer over exposed surfaces of the amorphous germanium layer, and performing a metal-induced crystallization (MIC) process on the amorphous germanium layer having the overlying metal layer to convert the amorphous germanium layer to a crystalline germanium layer and to activate the implanted dopant.

Abstract: A heterojunction III-V photovoltaic (PV) cell includes a base layer comprising a III-V substrate, the base layer being less than about 20 microns thick; an intrinsic layer located on the base layer; an amorphous silicon layer located on the intrinsic layer; and a transparent conducting oxide layer located on the amorphous silicon layer.

Abstract: A semiconductor device and a method of fabricating a semiconductor device are disclosed. Embodiments of the invention use a photosensitive self-assembled monolayer to pattern the surface of a substrate into hydrophilic and hydrophobic regions, and an aqueous (or alcohol) solution of a dopant compound is deposited on the substrate surface. The dopant compound only adheres on the hydrophilic regions. After deposition, the substrate is coated with a very thin layer of oxide to cap the compounds, and the substrate is annealed at high temperatures to diffuse the dopant atoms into the silicon and to activate the dopant. In one embodiment, the method comprises providing a semiconductor substrate including an oxide surface, patterning said surface into hydrophobic and hydrophilic regions, depositing a compound including a dopant on the substrate, wherein the dopant adheres to the hydrophilic region, and diffusing the dopant into the oxide surface of the substrate.

Abstract: A heterojunction III-V photovoltaic (PV) cell includes a base layer comprising a III-V substrate, the base layer being less than about 20 microns thick; an intrinsic layer located on the base layer; an amorphous silicon layer located on the intrinsic layer; and a transparent conducting oxide layer located on the amorphous silicon layer.

Abstract: A multijunction photovoltaic (PV) cell includes a bottom flexible substrate and a bottom metal layer located on the bottom flexible substrate. The multijunction photovoltaic cell also includes a semiconductor layer located on the bottom metal layer and a stack having a plurality of junctions located on the semiconductor layer, each of the plurality of junctions having a respective bandgap. The pluralities of junctions are ordered from the junction having the smallest bandgap being located on the substrate to the junction having the largest bandgap being located on top of the stack.

Abstract: A method for forming a heterojunction III-V photovoltaic (PV) cell includes performing layer transfer of a base layer from a wafer of a III-V substrate, the base layer being less than about 20 microns thick; forming an intrinsic layer on the base layer; forming an amorphous silicon layer on the intrinsic layer; and forming a transparent conducting oxide layer on the amorphous silicon layer. A heterojunction III-V photovoltaic (PV) cell includes a base layer comprising a III-V substrate, the base layer being less than about 20 microns thick; an intrinsic layer located on the base layer; an amorphous silicon layer located on the intrinsic layer; and a transparent conducting oxide layer located on the amorphous silicon layer.

Abstract: A method for fabrication of a multijunction photovoltaic (PV) cell includes providing a stack comprising a plurality of junctions on a substrate, each of the plurality of junctions having a respective bandgap, wherein the plurality of junctions are ordered from the junction having the smallest bandgap being located on the substrate to the junction having the largest bandgap being located on top of the stack; forming a top metal layer, the top metal layer having a tensile stress, on top of the junction having the largest bandgap; adhering a top flexible substrate to the metal layer; and spalling a semiconductor layer from the substrate at a fracture in the substrate, wherein the fracture is formed in response to the tensile stress in the top metal layer.

Abstract: A single-junction photovoltaic cell includes a doped layer comprising a dopant diffused into a semiconductor substrate; a patterned conducting layer formed on the doped layer; a semiconductor layer comprising the semiconductor substrate located on the doped layer on a surface of the doped layer opposite the patterned conducting layer; and an ohmic contact layer formed on the semiconductor layer.

Abstract: A method for forming a single-junction photovoltaic cell includes forming a dopant layer on a surface of a semiconductor substrate; diffusing the dopant layer into the semiconductor substrate to form a doped layer of the semiconductor substrate; forming a metal layer over the doped layer, wherein a tensile stress in the metal layer is configured to cause a fracture in the semiconductor substrate; removing a semiconductor layer from the semiconductor substrate at the fracture; and forming the single junction photovoltaic cell using the semiconductor layer. A single-junction photovoltaic cell includes a doped layer comprising a dopant diffused into a semiconductor substrate; a patterned conducting layer formed on the doped layer; a semiconductor layer comprising the semiconductor substrate located on the doped layer on a surface of the doped layer opposite the patterned conducting layer; and an ohmic contact layer formed on the semiconductor layer.

Abstract: Embodiments of this invention provide a method to fabricate an electrical contact. The method includes providing a substrate of a compound Group III-V semiconductor material having at least one electrically conducting doped region adjacent to a surface of the substrate. The method further includes fabricating the electrical contact to the at least one electrically conducting doped region by depositing a single crystal layer of germanium over the surface of the substrate so as to at least partially overlie the at least one electrically conducting doped region, converting the single crystal layer of germanium into a layer of amorphous germanium by implanting a dopant, forming a metal layer over exposed surfaces of the amorphous germanium layer, and performing a metal-induced crystallization (MIC) process on the amorphous germanium layer having the overlying metal layer to convert the amorphous germanium layer to a crystalline germanium layer and to activate the implanted dopant.

Abstract: Embodiments of this invention provide a method to fabricate an electrical contact. The method includes providing a substrate of a compound Group III-V semiconductor material having at least one electrically conducting doped region adjacent to a surface of the substrate. The method further includes fabricating the electrical contact to the at least one electrically conducting doped region by depositing a single crystal layer of germanium over the surface of the substrate so as to at least partially overlie the at least one electrically conducting doped region, converting the single crystal layer of germanium into a layer of amorphous germanium by implanting a dopant, forming a metal layer over exposed surfaces of the amorphous germanium layer, and performing a metal-induced crystallization (MIC) process on the amorphous germanium layer having the overlying metal layer to convert the amorphous germanium layer to a crystalline germanium layer and to activate the implanted dopant.

Abstract: Manufacturing a thin film direct bandgap semiconductor active solar cell device comprises providing a source substrate having a surface and disposing on the surface a stress layer having a stress layer surface area in contact with and bonded to the surface of the source substrate. Operatively associating a handle foil with the stress layer and applying force to the handle foil separates the stress layer from the source substrate, and leaves a portion of the source substrate on the stress layer surface substantially corresponding to the area in contact with the surface of the source substrate. The portion is less thick than the source layer. The stress layer thickness is below that which results in spontaneous spalling of the source substrate. The source substrate may comprise an inorganic single crystal or polycrystalline material such as Si, Ge, GaAs, SiC, sapphire, or GaN. The stress layer may comprise a flexible material.

Abstract: A multijunction photovoltaic (PV) cell includes a bottom flexible substrate and a bottom metal layer located on the bottom flexible substrate. The multijunction photovoltaic cell also includes a semiconductor layer located on the bottom metal layer and a stack having a plurality of junctions located on the semiconductor layer, each of the plurality of junctions having a respective bandgap. The pluralities of junctions are ordered from the junction having the smallest bandgap being located on the substrate to the junction having the largest bandgap being located on top of the stack.

Abstract: A method for fabrication of a multijunction photovoltaic (PV) cell includes forming a stack comprising a plurality of junctions on a substrate, each of the plurality of junctions having a respective bandgap, wherein the plurality of junctions are ordered from the junction having the largest bandgap being located on the substrate to the junction having the smallest bandgap being located on top of the stack; forming a metal layer, the metal layer having a tensile stress, on top of the junction having the smallest bandgap; adhering a flexible substrate to the metal layer; and spalling a semiconductor layer from the substrate at a fracture in the substrate, wherein the fracture is formed in response to the tensile stress in the metal layer.

Abstract: Manufacturing a thin film direct bandgap semiconductor active solar cell device comprises providing a source substrate having a surface and disposing on the surface a stress layer having a stress layer surface area in contact with and bonded to the surface of the source substrate. Operatively associating a handle foil with the stress layer and applying force to the handle foil separates the stress layer from the source substrate, and leaves a portion of the source substrate on the stress layer surface substantially corresponding to the area in contact with the surface of the source substrate. The portion is less thick than the source layer. The stress layer thickness is below that which results in spontaneous spalling of the source substrate. The source substrate may comprise an inorganic single crystal or polycrystalline material such as Si, Ge, GaAs, SiC, sapphire, or GaN. The stress layer may comprise a flexible material.

Abstract: Imparting a controlled amount of stress in an assembly comprising a semiconductor circuit on a substrate comprises depositing a tensile stressed metal film stressor layer onto the surface of the circuit. Establishing a fracture region below electrically active regions of the circuit, adhering a foil handle to the assembly and pulling it away from the assembly induces mechanical fracture in the fracture region below the electrically active regions. The mechanical fracture propagates parallel and laterally to the surface of the substrate and below the circuit to produce a thin flexible circuit on a residual substrate. The circuit is under compressive strain that is changed by modifying the stressor layer or residual substrate. Individualized circuits or a circuit may also be defined above the fracture by dividing the circuit into preselected regions with surrounding trenches before fracture. We harvest the circuit(s) by pulling the foil handle away from the assembly.

Abstract: A method for manufacturing a thin film direct bandgap semiconductor active solar cell device comprises providing a source substrate having a surface and disposing on the surface a stress layer having a stress layer surface area in contact with and bonded to the surface of the source substrate. Operatively associating a handle foil with the stress layer and applying force to the handle foil separates the stress layer from the source substrate, and leaves a portion of the source substrate on the stress layer surface substantially corresponding to the area in contact with the surface of the source substrate. The portion is less thick than the source layer. The stress layer thickness is below that which results in spontaneous spalling of the source substrate. The source substrate may comprise an inorganic single crystal or polycrystalline material such as Si, Ge, GaAs, SiC, sapphire, or GaN. In one embodiment the stress layer comprises a flexible material.