Publications by authors named "R L Myers-Ward"

Intercalation is a promising technique to modify the structural and electronic properties of 2D materials on the wafer scale for future electronic device applications. Yet, few reports to date demonstrate 2D intercalation as a viable technique on this scale. Spurred by recent demonstrations of mm-scale sensors, we use hydrogen intercalated quasi-freestanding bilayer graphene (hQBG) grown on 6H-SiC(0001), to understand the electronic properties of a large-area (16 mm) device.

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Strong circularly polarized excitation opens up the possibility to generate and control effective magnetic fields in solid state systems, e.g., via the optical inverse Faraday effect or the phonon inverse Faraday effect.

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Article Synopsis
  • This study uses femtosecond-THz optical pump probe spectroscopy to examine how quickly hot carriers cool in quasi-free standing bilayer epitaxial graphene that has undergone hydrogen intercalation.
  • The researchers found that the cooling decay times are longer, between 2.6 to 6.4 picoseconds, compared to monolayer graphene, and these times increase with higher excitation intensities.
  • The increased decay times are due to the separation of the graphene layer from the silicon carbide substrate after hydrogen intercalation, and the cooling is primarily facilitated by electron-optical phonon scattering rather than the supercollision mechanism.
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The electrochemical detection of heavy metal ions is reported using an inexpensive portable in-house built potentiostat and epitaxial graphene. Monolayer, hydrogen-intercalated quasi-freestanding bilayer, and multilayer epitaxial graphene were each tested as working electrodes before and after modification with an oxygen plasma etch to introduce oxygen chemical groups to the surface. The graphene samples were characterized using X-ray photoelectron spectroscopy, atomic force microscopy, Raman spectroscopy, and van der Pauw Hall measurements.

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Electron emission from quasi-freestanding bilayer epitaxial graphene (QFEG) on a silicon carbide substrate is reported, demonstrating emission currents as high as 8.5A, at ∼200 °C, under 0.3 Torr vacuum.

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