Application of graphene-based flexible antennas in consumer electronic devices

We describe the fabrication and characterization of Near-Field Communication (NFC) devices based on highly flexible, carbon-based antennas composed of stacked graphene multilayers. This material features a high value of conductivity (4.20 * 10 5 S/m) comparable to monocrystalline graphite, but is much more flexible and processable. We first studied the replacement of metal with carbon antennas using computer modeling, to select the best design. Then we manufactured several devices to be used according to the communication protocol ISO/IEC 15693. The inductance of the G-paper antennas was tested before and after hundreds of thousands of bending cycles at bending radii of 45 and 90 mm. During bending the self-resonance frequency and inductance peak showed minimal variation and the resistance at 1 MHz changed from 33.09 Ω to 34.18 Ω outperforming standard, commercial metallic antennas. The devices were successfully tested by exchanging data with a smartphone and other commercial NFC readers, matching the performance of standard, commercial metallic antennas. The graphene antennas could be deposited on different standard polymeric substrates or on textiles. Smart cards, flexible NFC tags and wearable NFC bracelets were prepared in this way to be used in electronic keys, business cards and other typical NFC applications

X-RAY PHOTOELECTRON-SPECTROSCOPY AND SCANNING ELECTRON-MICROSCOPY OF BETA-FESI2 FILMS GROWN BY ION-BEAM-ASSISTED DEPOSITION

This paper reports the investigation of polycrystalline beta-FeSi2 films grown by Ion Beam Assisted Deposition (IBAD), performed by using a broad Ar+ beam bombarding (001) Si substrates during the evaporation of Fe atoms. Several energies (200-650 eV) and current densities (10-70 muA cm-2) have been used for the Ar+ beam, keeping the Fe evaporation rate at about 0.08 nm s-1. The formation of the silicide was achieved by in situ thermal annealing at T = 600-degrees-C, performed during or after the deposition process. Rutherford Backscattering Spectroscopy (RBS), Scanning Electron Microscopy (SEM) and X-Ray Photoelectron Spectroscopy (XPS) have been used to study the stoichiometry, the morphology and the chemical status of several samples obtained using different ion beam parameters. Strong morphological improvements, such as smoothing and pinhole closing, are observed for the IBAD films grown during thermal annealing. The XPS depth profiling technique has been used to investigate the morphology of the silicide/Si interface

Initial and Final-State Effects in Photoemission from Gold Clusters

Size-dependent effects in the core-peak and Fermi-edge features of Au-cluster photoemission spectra have been investigated for two different substrates: polycrystalline and highly oriented pyrolytic graphite. In contrast with common substrates such as amorphous carbon, graphite or silicon dioxide, for pyrolitic graphite it has been found that steps or cavities bind the clusters, that assume non-spherical shapes. The use of pyrolitic graphite in our experiments, therefore, enabled us to investigate clusters with asymmetrical shape, in which the electron-hole final-state interaction observed for spheric clusters should be greatly reduced. We show that the spectral energy shifts with changing coverage detected for such clusters cannot be explained with a final-state mechanism alone - and indicate that initial-state as well as final-state effects are present for the Au 4f core peaks