Abstract: Light-emitting devices having a multiple quantum well (MQW) pin diode structure and methods of making and using the devices are provided. The light-emitting devices include: a tunneling heterojunction as a hole injector; an n-type contact; and a light-emitting active region disposed between the tunneling heterojunction and the n-type contact. The tunneling heterojunction facilitates interband tunneling hole injection under bias, whereby electrons in the valence band of a p-type group III-nitride semiconductor tunnel directly into the conduction band of the n-type doped semiconductor, resulting in the generation of holes in the p-type group III-nitride.

Abstract: Radiation detectors based on high electron mobility transistors (HEMTs) are provided. Methods for detecting ultraviolet radiation using the HEMTs are also provided. The transistors are constructed from an intrinsic high bandgap semiconductor material with a built-in polarization field sandwiched between graphene and a two-dimensional electron gas (2DEG).

Abstract: Switches for electromagnetic radiation, including radiofrequency switches and optical switches, are provided. Also provided are methods of using the switches. The switches incorporate layers of high quality VO2 that are composed of a plurality of connected crystalline VO2 domains having the same crystal structure and orientation.

Abstract: Light-emitting devices having a multiple quantum well (MQW) diode structure and methods of making and using the devices are provided. The devices include aluminum nitride/aluminum oxide bilayers on their hole injection layers. The bilayers improve the energy efficiency of the devices, with respect to devices that lack the bilayers or that include only a layer of aluminum oxide on their hole injection layers.

Abstract: Optoelectronic devices that use very thin single-crystalline inorganic semiconductor films as phonon-absorbing layers in combination with non-lattice optical cavities are provided.

Abstract: Light-emitting devices having a multiple quantum well (MQW) pin diode structure are provided. The light-emitting devices include a multilayered p-type contact composed of a heavily p-type doped hole injection layer and a thin p-type group III-nitride layer. The materials of the hole injection layer and the p-type group III-nitride layer are separated by a layer of a material that allows current tunneling through the heterogeneous junction formed between the lattice mismatched materials.

Abstract: Switches for electromagnetic radiation, including radiofrequency switches and optical switches, are provided. Also provided are methods of using the switches. The switches incorporate layers of high quality VO2 that are composed of a plurality of connected crystalline VO2 domains having the same crystal structure and orientation.

Abstract: Stretchable high frequency transmission lines and high-frequency filters comprising the transmission lines are provided. The transmission lines provide low power loss, even at microwave and millimeter wave frequencies. The transmission lines are thin and flexible and can be stretched without a significant degradation of their scattering parameters. As a result, the transmission lines have applications as interconnects in stretchable and flexible integrated circuits (IC) and circuit device components, such as flexible transistors and flexible diodes.

Abstract: Tandem solar cells comprising two or more solar cells connected in a solar cell stack via pn diode tunnel junctions and methods for fabricating the tandem solar cells using epitaxial lift off and transfer printing are provided. The tandem solar cells have improved tunnel junction structures comprising a current tunneling layer integrated between the p and n layers of the pn diode tunnel junction that connects the solar cells.

Abstract: Photodetectors based on hydrogen-doped, single-crystalline germanium, including waveguide integrated photodetectors for photonic chip applications are provided. Hydrogen doping provides the single-crystalline germanium with increased radiation absorption in the near infrared region of the electromagnetic spectrum, including at wavelengths of 1550 nm and above.

Abstract: Vertical cavity light emitting sources that utilize patterned membranes as reflectors are provided. The vertical cavity light emitting sources have a stacked structure that includes an active region disposed between an upper reflector and a lower reflector. The active region, upper reflector and lower reflector can be fabricated from single or multi-layered thin films of solid states materials (“membranes”) that can be separately processed and then stacked to form a vertical cavity light emitting source.

Abstract: Provided herein are methods of directed self-assembly (DSA) on atomic layer chemical patterns and related compositions. The atomic layer chemical patterns may be formed from two-dimensional materials such as graphene. The atomic layer chemical patterns provide high resolution, low defect directed self-assembly. For example, DSA on a graphene pattern can be used achieve ten times the resolution of DSA that is achievable on a three-dimensional pattern such as a polymer brush. Assembly of block copolymers on the atomic layer chemical patterns may also facilitate subsequent etch, as the atomic layer chemical patterns are easier to etch than conventional pattern materials.

Abstract: Tandem solar cells comprising two or more solar cells connected in a solar cell stack via pn diode tunnel junctions and methods for fabricating the tandem solar cells using epitaxial lift off and transfer printing are provided. The tandem solar cells have improved tunnel junction structures comprising a current tunneling layer integrated between the p and n layers of the pn diode tunnel junction that connects the solar cells.

Abstract: Power generators that incorporate porous electric generation layers composed of mechanoradical-forming polymers are provided. Also provided are methods for using the generators to convert mechanical energy into and electrical signal to power electronic devices. The porous electric generation material includes an organic polymer that forms free radicals when covalent bonds are homolytically ruptured upon the application of a compressive force to the porous structure.

Abstract: Devices for detecting electrical activity in electrically active biological tissues and methods for using the devices are provided. The devices include an electrode array that is configured for implantation on electrically active biological tissue. The electrode array comprises a plurality of electrode sites comprising one or more layers of transparent, electrically conductive graphene disposed on a transparent substrate.

Abstract: Boron-doped diamond and methods for making it are provided. The doped diamond is made using an ultra-thin film of heavily boron-doped silicon as a dopant carrying material in a low temperature thermal diffusion doping process.

Abstract: Composite materials comprising electrically conductive particles in a form-stable phase change materials (PCMs) are provided. Also provided as radiation sensors incorporating the composites and methods for detecting radiation using the composites. The PCMs comprise crosslinked polyether polyol that undergoes a reversible solid-solid phase change upon heating. Prior to the phase change, the crosslinked polyether polyol comprises microscopic crystalline domains. When the PCM is heated beyond its phase transition temperature these microscopic crystalline domains melt. However, the form-stable PCMs retain their solid form at the macroscopic level.

Abstract: Stretchable high frequency transmission lines and high-frequency filters comprising the transmission lines are provided. The transmission lines provide low power loss, even at microwave and millimeter wave frequencies. The transmission lines are thin and flexible and can be stretched without a significant degradation of their scattering parameters. As a result, the transmission lines have applications as interconnects in stretchable and flexible integrated circuits (IC) and circuit device components, such as flexible transistors and flexible diodes.

Abstract: Boron-doped diamond and methods for making it are provided. The doped diamond is made using an ultra-thin film of heavily boron-doped silicon as a dopant carrying material in a low temperature thermal diffusion doping process.

Abstract: A circuit for three-phase detection, a method for three-phase detection and a compressor are provided. The circuit for three-phase detection includes a first optical coupler and a second optical coupler. A first input end and a second input end of the first optical coupler are respectively connected to a first phase wire and a third phase wire of a power supply assembly, and a first output end of the first optical coupler provides a first output signal. A first input end and a second input end of the second optical coupler are respectively connected to a second phase wire and the third phase wire of the power supply assembly, and a first output end of the second optical coupler provides a second output signal. The first output signal and the second output signal are used to indicate a phase state of a three-phase alternating current of the power supply assembly.