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We demonstrate field emission from an integrated three-terminal device using a suspended planar graphene edge as the source of vacuum electrons. Energy spectra of the emitted electrons confirm the field-emission mechanism. The energy spectra produced by graphene grown by chemical vapor deposition and reduced graphene oxide are compared. The drain-source voltage required to produce a given drain current increases when negative voltages are applied to the gate, confirming field-effect transistor operation. The emission current rises exponentially with inverse voltage over the measured current range from 1 pA to 10 nA. The current-voltage characteristics are consistent with tunneling through barrier potentials calculated numerically from the device geometry.

The properties of reduced graphene oxide (GO) are reported from a non-chemical reduction method. Ultra-high vacuum annealing of GO films in the thickness of 1–80 nm was studied by XPS, AFM, UV-Vis-NIR, Raman, and TEM to observe the controlled removal of oxygen. We observed the loss of hydroxyl (C-OH) at low temperatures (

Terahertz (THz) Faraday rotation measurements were performed to investigate carrier dynamics in p-type Chemical vapor deposition (CVD) graphene. We used static and time-resolved polarization-sensitive THz transmission measurements in a magnetic field to probe free carriers in GaAs, InP, and Graphene. Static measurements probe the equilibrium carrier density and momentum scattering rate. Time-resolved (optical pump/THz probe) measurements probe the change in these quantities following photoexcitation. In a typical CVD graphene sample, we found that 0.5 ps following photoexcitation with 1 × 1013 photons/cm2 pulses at 800 nm the effective hole scattering time decreased from 37 fs to 34.5 fs, while the carrier concentration increased from 2.0 × 1012 cm−2 to 2.04 × 1012 cm−2, leading to a transient decrease in the conductivity of the film.

Spin-injection into silicon from a ferromagnetic metal requires a solution to the conductivity mismatch. Oxide tunnel barriers such as MgO, Al2O3, or SiO2 are typically used to solve this problem, but often include defects and must be several monolayers thick to avoid pinholes. At these thicknesses, the overall tunnel-barrier becomes highly resistive, preventing these junctions to be used in devices based on local magnetoresistance. Besides providing a spin dependent interface resistance, these barriers also prevent metal ions from diffusing into silicon, which would severely compromise device performance. Here, we show that we can lower the junction resistance by 2–3 orders of magnitude when using a single layer of graphene as the tunnel barrier rather than SiO2 or Al2O3. Hanle measurements show that the spin lifetime is independent of the tunnel barrier material (graphene, Al2O3, SiO2), demonstrating that the lifetime measured is not dominated by some characteristics of the tunnel barrier. The graphene provides a highly uniform barrier, with well-controlled thickness and minimal defect and trapped charge density, while successfully circumventing the conductivity mismatch between a ferromagnetic metal and Si and preventing metal ion diffusion from the FM contact.