Abstract: Described herein are devices and methods that utilize three-dimensional topological semimetals (including Dirac, Weyl and nodal line) that may be useful in advanced electronic devices. The Fermi level in three dimensional topological semimetals can be significantly shifted in energy when forming a heterojunction with a semiconductor or metal. This has unintended and sometimes negative consequences for device performance. Described herein are designs and methods to modify the heterostructures to either suppress Fermi level movement or to produce an intentional shift to allow for the use of these improved semimetal devices.

Abstract: Described herein are optoelectronic devices and methods incorporating strain balanced direct bandgap AlxIn1-xP multiple quantum wells. The described devices are strain balanced in that the net strain between the ordered quantum wells and barriers is low, or in some cases zero. Advantageously, the described devices may be specifically designed for higher efficiency than existing AlxIn1-xP and may be grown on commercially available GaAs substrates.

Abstract: The present disclosure relates to a device that includes a blue-emitting light emitting diode (LED) capable of emitting blue light at a first intensity and a non-blue-emitting LED capable of emitting light having a color other than blue, at a second intensity, where the first intensity is variable.

Abstract: High bandgap alloys for high efficiency optoelectronics are disclosed. An exemplary optoelectronic device may include a substrate, at least one Al1-xInxP layer, and a step-grade buffer between the substrate and at least one Al1-xInxP layer. The buffer may begin with a layer that is substantially lattice matched to GaAs, and may then incrementally increase the lattice constant in each sequential layer until a predetermined lattice constant of Al1-xInxP is reached.

Abstract: Voltage-matched thin film multijunction solar cell and methods of producing cells having upper CdTe pn junction layers formed on a transparent substrate which in the completed device is operatively positioned in a superstate configuration. The solar cell also includes a lower pn junction formed independently of the CdTe pn junction and an insulating layer between CdTe and lower pn junctions. The voltage-matched thin film multijunction solar cells further include a parallel connection between the CdTe pn junction and lower pn junctions to form a two-terminal photonic device. Methods of fabricating devices from independently produced upper CdTe junction layers and lower junction layers are also disclosed.

Abstract: Voltage-matched monolithic thin film multijunction solar cell and methods of producing cells having a first pn junction with a first band-gap energy, a second pn junction with a second band-gap energy and an insulating layer between the first and second pn junctions. The voltage-matched monolithic thin film multijunction solar cells further include a parallel connection between the first and second pn junctions to form a two-terminal photonic device.

Abstract: A method of producing semiconductor materials and devices that incorporate the semiconductor materials are provided. In particular, a method is provided of producing a semiconductor material, such as a III-V semiconductor, on a spinel substrate using a sacrificial buffer layer, and devices such as photovoltaic cells that incorporate the semiconductor materials. The sacrificial buffer material and semiconductor materials may be deposited using lattice-matching epitaxy or coincident site lattice-matching epitaxy, resulting in a close degree of lattice matching between the substrate material and deposited material for a wide variety of material compositions. The sacrificial buffer layer may be dissolved using an epitaxial liftoff technique in order to separate the semiconductor device from the spinel substrate, and the spinel substrate may be reused in the subsequent fabrication of other semiconductor devices.

Abstract: Voltage-matched thin film multijunction solar cell and methods of producing cells having upper CdTe pn junction layers formed on a transparent substrate which in the completed device is operatively positioned in a superstate configuration. The solar cell also includes a lower pn junction formed independently of the CdTe pn junction and an insulating layer between CdTe and lower pn junctions. The voltage-matched thin film multijunction solar cells further include a parallel connection between the CdTe pn junction and lower pn junctions to form a two-terminal photonic device. Methods of fabricating devices from independently produced upper CdTe junction layers and lower junction layers are also disclosed.

Abstract: A multijunction photovoltaic device (300) is provided. The multijunction photovoltaic device (300) includes a substrate (301) and one or more intermediate sub-cells (303a-303c) coupled to the substrate (301). The multijunction photovoltaic device (300) further includes a top sub-cell (304) comprising an AlxIn1-xP alloy coupled to the one or more intermediate sub-cells (303a-303c) and lattice mismatched to the substrate (301).

Abstract: A method of producing semiconductor materials and devices that incorporate the semiconductor materials are provided. In particular, a method is provided of producing a semiconductor material, such as a III-V semiconductor, on a spinel substrate using a sacrificial buffer layer, and devices such as photovoltaic cells that incorporate the semiconductor materials. The sacrificial buffer material and semiconductor materials may be deposited using lattice-matching epitaxy or coincident site lattice-matching epitaxy, resulting in a close degree of lattice matching between the substrate material and deposited material for a wide variety of material compositions. The sacrificial buffer layer may be dissolved using an epitaxial liftoff technique in order to separate the semiconductor device from the spinel substrate, and the spinel substrate may be reused in the subsequent fabrication of other semiconductor devices.

Abstract: High bandgap alloys for high efficiency optoelectronics are disclosed. An exemplary optoelectronic device may include a substrate, at least one Al1-xInxP layer, and a step-grade buffer between the substrate and at least one Al1-xInxP layer. The buffer may begin with a layer that is substantially lattice matched to GaAs, and may then incrementally increase the lattice constant in each sequential layer until a predetermined lattice constant of Al1-xInxP is reached.