We obtain a monolayer graphene on epitaxial silicon carbide on silicon substrates via solid source growth mediated by a thin Ni-Cu alloy. Raman spectroscopy consistently shows an I D /I G band ratio as low as ~0.2, indicating that the graphene obtained through this method is to-date the best quality monolayer grown on epitaxial silicon carbide films on silicon. We describe the key steps behind the graphene synthesis on the basis of extensive physical, chemical and morphological analyses. We conclude that (1) the oxidation, amorphisation and silicidation of the silicon carbide surface mediated by the Ni, (2) the liquid-phase epitaxial growth of graphene as well as (3) the self-limiting graphitization provided the molten Cu catalyst, are key characteristics of this novel synthesis method.

This study investigated the effectiveness of a graphene- and aptamer-based field-effect-transistor-like (FET-like) sensor in detecting lead and potassium ions. The sensor consists of a graphene-covered Si/SiO2 wafer with thrombin binding aptamer (TBA) attached to the graphene layer and terminated by a methylene blue (MB) molecule. K(+) and Pb(2+) both bind to TBA and cause a conformational change, which results in MB moving closer to the graphene surface and donating an electron. Thus, the abundance of K(+) and Pb(2+) can be determined by monitoring the current across the source and drain channel. Device transfer curves were obtained with ambipolar field effect observed. Current readings were taken for K(+) concentrations of 100 μM to 50 mM and Pb(2+) concentrations of 10 μM to 10 mM. As expected, I d decreased as ion concentration increased. In addition, there was a negative shift in V Dirac in response to increased ion concentration.

We report growth and characterization of epitaxial α-Sn thin films grown on CdTe(111)B. Noninvasive techniques verify the film's pseduomorphic growth before fabrication of magnetotransport devices, overcoming ex-situ obstacles on uncapped films for measurement in the Hall bar geometry. We identify a transition to metallic behavior at low temperature with large magnetoresistance, high mobility, and quantum oscillations tentatively suggesting an n-type Dirac semimetallic channel. A parallel p-type dopant channel with high carrier density is seen to dominate at thinner film thicknesses. Careful preparation of the CdTe surface before growth is considered crucial to attain a low dopant density and accessible topological states on an insulating substrate. arXiv:1903.06723v2 [cond-mat.str-el]

Articles you may be interested inOptimization of postgrowth electron-beam curing for focused electron-beam-induced Pt deposits Electron beam induced deposition of low resistivity platinum from Pt ( P F 3 ) 4 a) Electron beam induced deposition ͑EBID͒ is of interest as a damage-free and resist-less means of incorporating nonconventional materials such as polymer fibers, nanowires, and carbon nanotubes into integrated circuits. A novel inorganic platinum precursor-Pt͑PF 3 ͒ 4 -is investigated in this work, as it has previously been demonstrated to deposit Pt with resistivities close to bulk Pt when deposited using high dose rates. In this work, the effects of 100 and 200°C anneals on these Pt deposits are examined. Annealing these deposits is observed to shrink the deposits and decrease their P content. As a result, the measured Pt resistivities decreased with annealing by factors of 1.6-9.9.