Amorphous carbon pillars grown by focused ion beam induced chemical vapor deposition (FIB-CVD) had been considered to form in a cylindrical double structure. In this structure, the core containing Ga originating from the primary ion is surrounded by an amorphous carbon shell grown by the secondary electrons that were emitted during the inelastic scattering process of the primary ions penetration. We measured the Young's modulus in a series of inclined pillars; the thickness of the pillars was reduced with the inclination. However, the Young's modulus of the inclined pillars of thinner diameter increased. Here, we found that such FIB-CVD pillars had an elastic double structure that is comprised of a very stiffened core with 300 GPa of Young's modulus, and an extremely soft shell having 30 GPa of Young's modulus. We also confirmed that the oxygen plasma thinning of the perpendicular pillars considerably increased the Young's modulus of the FIB-CVD pillars.
We demonstrated a new process for synthesizing a graphene sheet at the interface between solid amorphous carbon and liquid gallium. The insolubility of carbon in gallium strongly restricted the depth of graphitization, but a multilayered graphene sheet having four to six layers of graphene was produced over the entire area of the interface immediately beneath the liquid gallium. We also demonstrated the operation of an electric-field-effect device fabricated on the multilayered graphene with a back-gated configuration, and a maximum conductance modulation of 40% was observed for an applied gate voltage ranging from -100 to +100 V.
A method for fabricating single-crystalline nanogaps on Si substrates was developed. Polycrystalline Pt nanowires on Si substrates were broken down by current flow under various gaseous environments. The crystal structure of the nanogap electrode was evaluated using scanning electron microscopy and transmission electron microscopy. Nanogap electrodes sandwiched between Pt-large-crystal-grains were obtained by the breakdown of the wire in an O(2) or H(2) atmosphere. These nanogap electrodes show intense spots in the electron diffraction pattern. The diffraction pattern corresponds to Pt (111), indicating that single-crystal grains are grown by the electrical wire breakdown process in an O(2) or H(2) atmosphere. The Pt wires that have (111)-texture and coherent boundaries can be considered ideal as interconnectors for single molecular electronics. The simple method for fabrication of a single-crystalline nanogap is one of the first steps toward standard nanogap electrodes for single molecular instruments and opens the door to future research on physical phenomena in nanospaces.
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