August Yurgens

Graphene Conductance Uniformity Mapping

We demonstrate a combination of micro four-point probe (M4PP) and non-contact terahertz time-domain spectroscopy (THz-TDS) measurements for centimeter scale quantitative mapping of the sheet conductance of large area chemical vapor deposited graphene films. Dual configuration M4PP measurements, demonstrated on graphene for the first time, provide valuable statistical insight into the influence of microscale defects on the conductance, while THz-TDS has potential as a fast, non-contact metrology method for mapping of the spatially averaged nanoscopic conductance on wafer-scale graphene with scan times of less than a minute for a 4-in. wafer. The combination of M4PP and THz-TDS conductance measurements, supported by micro Raman spectroscopy and optical imaging, reveals that the film is electrically continuous on the nanoscopic scale with microscopic defects likely originating from the transfer process, dominating the microscale conductance of the investigated graphene film.

Frame assisted H2O electrolysis induced H2 bubbling transfer of large area graphene grown by chemical vapor deposition on Cu

An improved technique for transferring large area graphene grown by chemical vapor deposition on copper is presented. It is based on mechanical separation of the graphene/copper by H2 bubbles during H2O electrolysis, which only takes a few tens of seconds while leaving the copper cathode intact. A semi-rigid plastic frame in combination with thin polymer layer span on graphene gives a convenient way of handling- and avoiding wrinkles and holes in graphene. Optical and electrical characterizations prove the graphene quality is better than that obtained by traditional wet etching transfer. This technique appears to be highly reproducible and cost efficient.

Magnetic Field Dependence of the Superconducting Gap and the Pseudogap in Bi2212 and HgBr2-Bi2212, Studied by Intrinsic Tunneling Spectroscopy

Intrinsic tunneling spectroscopy in high magnetic field (

Large-area uniform graphene-like thin films grown by chemical vapor deposition directly on silicon nitride

H

Noncatalytic chemical vapor deposition of graphene on high-temperature substrates for transparent electrodes

) is used for a direct test of superconducting features in a quasiparticle density of states of high-

Low Partial Pressure Chemical Vapor Deposition of Graphene on Copper

T_c

Controllable chemical vapor deposition of large area uniform nanocrystalline graphene directly on silicon dioxide

superconductors. We were able to distinguish with a great clarity two co-existing gaps: (i) the superconducting gap, which closes as

Pseudo-gap features of intrinsic tunneling in (HgBr{sub 2})-Bi2212 single crystals

H \to H_{c2}(T)

Growth mechanism of graphene on platinum: Surface catalysis and carbon segregation

and

Intrinsic tunneling spectra of Bi2(Sr(2-x)Lax)CuO(6+delta).

T\to T_c(H)