Abstract: A sensitive and selective, in-line method to measure and validate the sulfur content at ppb levels in both the liquid and gas phase of an analyte. The method includes patterning graphene, for example to form a mesa structure comprising horizontal or vertical lines or an array of multidentate star features; functionalizing the patterned graphene and attaching nanoparticles to the functionalized graphene to form a device; exposing the device to an analyte in the gas or liquid phase; detecting a change in electrical response when sulfur is present in the analyte; and recovering the device for future use. Also disclosed is the related sulfur detector.

Abstract: A method for graphene functionalization that preserves electronic properties and enables nanoparticles deposition comprising providing graphene, functionalizing the graphene via non-covalent or covalent functionalization, rinsing the graphene, drying the graphene, and forming functionalized graphene wherein the functionalized graphene preserves electronic properties and enables nanoparticles deposition. A functionalized graphene wherein the graphene functionalization preserves electronic properties and enables nanoparticles deposition.

Abstract: A sensitive and selective, in-line method to measure and validate the sulfur content at ppb levels in both the liquid and gas phase of an analyte. The method includes patterning graphene, for example to form a mesa structure comprising horizontal or vertical lines or an array of multidentate star features; functionalizing the patterned graphene and attaching nanoparticles to the functionalized graphene to form a device; exposing the device to an analyte in the gas or liquid phase; detecting a change in electrical response when sulfur is present in the analyte; and recovering the device for future use. Also disclosed is the related sulfur detector.

Abstract: Devices including graphene quantum dots yield extremely high performance THz bolometers, by measuring the current of hot electrons formed in the graphene source and drain electrodes of the device and propagating through the graphene quantum dot connected thereto. Devices may also include additional materials such as MoS2, as well as one or more gate electrodes to alter performance as needed.

Abstract: Systems and methods for growth of silicon carbide over a layer comprising graphene and/or hexagonal boron nitride, and related articles, are generally described. In some embodiments, a SiC film is fabricated over a layer comprising graphene and/or hexagonal boron nitride, which in turn is disposed over a substrate. The layer and/or the substrate may be lattice-matched with the SiC film to reduce defect density in the SiC film. The fabricated SiC film may then be removed from the substrate via, for example, a stressor attached to the SiC film. In certain cases, the layer serves as a reusable platform for growing SiC films and also serves a release layer that allows fast, precise, and repeatable release at the layer surface.

Abstract: A sensitive and selective, in-line method to measure and validate the sulfur content at ppb levels in both the liquid and gas phase of fuel. The method includes etching graphene, for example to form a mesa structure comprising horizontal or vertical lines or an array of multidentate star features; functionalizing the etched graphene and attaching metal oxide nanoparticles to the functionalized graphene to form a device; exposing the device to a fuel in the gas or liquid phase; detecting a change in conductivity when sulfur is present in the fuel; and recovering the device for future use. Also disclosed is the related in-line graphene-based ppb level sulfur detector for fuels.

Abstract: An electrochemical cell includes a working electrode in contact with an aqueous electrolyte solution, a counter electrode in contact with the aqueous electrolyte solution, and a reference electrode in contact with the aqueous electrolyte solution. The working electrode comprises a plasma modified epitaxial synthesized graphene surface fabricated on SiC.

Abstract: An article of manufacture includes a first graphene layer, a second graphene layer over the first graphene layer, the second graphene layer oriented at a first interlayer twist angle with respect to the first graphene layer and bonded by interlayer covalent bonds to the first graphene layer, and a third graphene layer over the second graphene layer, the third graphene layer oriented at a second interlayer twist angle with respect to the second graphene layer and bonded by interlayer covalent bonds to the second graphene layer. A multi-layer graphene article includes at least three graphene layers, each graphene layer being oriented at an interlayer twist angle with respect to an adjacent graphene layer and bonded by interlayer covalent bonds to the adjacent graphene layer.

Abstract: An article of manufacture includes a first graphene layer, a second graphene layer over the first graphene layer, the second graphene layer oriented at a first interlayer twist angle with respect to the first graphene layer and bonded by interlayer covalent bonds to the first graphene layer, and a third graphene layer over the second graphene layer, the third graphene layer oriented at a second interlayer twist angle with respect to the second graphene layer and bonded by interlayer covalent bonds to the second graphene layer. A multi-layer graphene article includes at least three graphene layers, each graphene layer being oriented at an interlayer twist angle with respect to an adjacent graphene layer and bonded by interlayer covalent bonds to the adjacent graphene layer.

Abstract: A new approach to graphene-enabled plasmonic resonant structures in the THz is demonstrated in a hybrid graphene-metal design in which the graphene acts as a gate-tunable inductor, and metal acts as a capacitive reservoir for charge accumulation. A large resonant absorption in graphene can be achieved using the metal-graphene plasmonic scheme, and the peak can approach 100% in an optimized device, ideal for graphene-based THz detectors. Using high mobility graphene (?>50000 cm2V?1s?1) will allow anomalously high resonant THz transmission (near 100%) through ultra-subwavelength graphene-filled metallic apertures at a resonance frequency that is gate tunable. This metal-graphene plasmonic scheme enables near perfect tunable THz filter or modulator.

Abstract: A method includes depositing a layer of silicon oxide onto a layer of silicon carbide; ion implanting the layer of silicon carbide, annealing the ion implanted layer of silicon carbide to produce defects within the layer of silicon carbide, performing photolithography using a mask layer on regions of the layer of silicon carbide to define regions for electrode deposition, removing the layer of silicon oxide from the layer of silicon carbide in the one or more regions for electrode deposition, forming one or more electrodes by depositing indium tin oxide (ITO) in each of the regions for electrode deposition, performing a first lift-off operation to remove the mask layer surrounding the electrodes, depositing a passivation and gate silicon oxide layer on top of the layer of silicon carbide and the electrodes, and performing a second lift-off operation to fabricate an optically transparent ITO gate between the electrodes.

Abstract: A sensitive and selective, in-line method to measure and validate the sulfur content at ppb levels in both the liquid and gas phase of fuel. The method includes etching graphene, for example to form a mesa structure comprising horizontal or vertical lines or an array of multidentate star features; functionalizing the etched graphene and attaching metal oxide nanoparticles to the functionalized graphene to form a device; exposing the device to a fuel in the gas or liquid phase; detecting a change in conductivity when sulfur is present in the fuel; and recovering the device for future use. Also disclosed is the related in-line graphene-based ppb level sulfur detector for fuels.

Abstract: A method of: providing an off-axis silicon carbide substrate, and etching the surface of the substrate with a dry gas, hydrogen, or an inert gas.

Abstract: A method of: providing an off-axis 4H—SiC substrate, and etching the surface of the substrate with hydrogen or an inert gas.

Abstract: An electrochemical cell includes a working electrode in contact with an aqueous electrolyte solution, a counter electrode in contact with the aqueous electrolyte solution, and a reference electrode in contact with the aqueous electrolyte solution. The working electrode comprises a plasma modified epitaxial synthesized graphene surface fabricated on SiC.

Abstract: A new approach to graphene-enabled plasmonic resonant structures in the THz is demonstrated in a hybrid graphene-metal design in which the graphene acts as a gate-tunable inductor, and metal acts as a capacitive reservoir for charge accumulation. A large resonant absorption in graphene can be achieved using the metal-graphene plasmonic scheme, and the peak can approach 100% in an optimized device, ideal for graphene-based THz detectors. Using high mobility graphene (?>50000 cm2V?1s?1) will allow anomalously high resonant THz transmission (near 100%) through ultra-subwavelength graphene-filled metallic apertures at a resonance frequency that is gate tunable. This metal-graphene plasmonic scheme enables near perfect tunable THz filter or modulator.

Abstract: A plasmon-enhanced terahertz graphene-based photodetector exhibits an increased absorption efficiency attained by utilizing a tunable plasmonic resonance in sub-wavelengths graphene micro-ribbons formed on SiC substrate in contact with an array of bi-metallic electrode lines. The orientation of the graphene micro-ribbons is tailored with respect to the array of sub-wavelengths bi-metallic electrode lines. The graphene micro-ribbons extend at the angle of approximately 45 degrees with respect to the electrode lines in the bi-metal electrodes array. The plasmonic mode is efficiently excited by an incident wave polarized perpendicular to the electrode lines, and/or to the graphene micro-ribbons. The absorption of radiation by graphene is enhanced through tunable geometric parameters (such as, for example, the width of the graphene micro-ribbons) and control of a carrier density in graphene achieved through tuning the gate voltage applied to the photodetector.

Abstract: A method for graphene functionalization that preserves electronic properties and enables nanoparticles deposition comprising providing graphene, functionalizing the graphene via non-covalent or covalent functionalization, rinsing the graphene, drying the graphene, and forming functionalized graphene wherein the functionalized graphene preserves electronic properties and enables nanoparticles deposition. A functionalized graphene wherein the graphene functionalization preserves electronic properties and enables nanoparticles deposition.

Abstract: A plasmon-enhanced terahertz graphene-based photodetector exhibits an increased absorption efficiency attained by utilizing a tunable plasmonic resonance in sub-wavelengths graphene micro-ribbons formed on SiC substrate in contact with an array of bi-metallic electrode lines. The orientation of the graphene micro-ribbons is tailored with respect to the array of sub-wavelengths bi-metallic electrode lines. The graphene micro-ribbons extend at the angle of approximately 45 degrees with respect to the electrode lines in the bi-metal electrodes array. The plasmonic mode is efficiently excited by an incident wave polarized perpendicular to the electrode lines, and/or to the graphene micro-ribbons. The absorption of radiation by graphene is enhanced through tunable geometric parameters (such as, for example, the width of the graphene micro-ribbons) and control of a carrier density in graphene achieved through tuning the gate voltage applied to the photodetector.

Abstract: An appropriately configured pulsed laser is focused onto a graphene sheet and is used to form a desired pattern in the graphene. When the laser pulse strikes the graphene, it modifies the bonding state of the carbon atoms in the graphene lattice, acting as a “blade” and causing a separation in the graphene sheet at the site of the laser pulse without causing damage to the surrounding graphene. The width of the separation, or “cut” in the graphene sheet can be controlled by controlling characteristics of the laser pulse such as beam shape, beam intensity, pulse width, repetition rate, and wavelength to produce a graphene material having desired electrical, optical, thermal, and/or mechanical properties.