Alberto Sacchetti

A two-step plasma processing for gold nanoparticles supported on silicon near-infrared plasmonics

A two-step sputtering methodology for fabricating gold nanoparticles supported on silicon with tuneable surface plasmon resonance down to the near-infrared spectral range has been developed. This methodology uses modification of the wettability of Si surfaces by an intermediate O2 plasma treatment to decouple diameter and height of nanoparticles as tuneable parameters to tailor the plasmon resonance.

Optical and electrical properties of nanostructured LaCoO3 thin films

Nanostructured lanthanum cobaltite thin films have been grown on silica substrates by hybrid chemical vapor deposition/sol-gel approaches. The refractive index and the extinction coefficient of the specimens have been determined in the spectral range of 0.75–6.5 eV by spectroscopic ellipsometry. The conductivity of the films as a function of temperature has been also investigated, highlighting the different electrical behavior of LaCoO3 nanosystems as a function of the adopted synthetic strategy.

Plasma ehnancement of metalorganic chemical vapor deposition and properties of Er2O3 nanostructured thin films

An O2 remote plasma metal organic chemical vapor deposition (RP-MOCVD) route is presented for tailoring the structural, morphological, and optical properties of Er2O3 thin films grown on Si(100) using the tris(isopropylcyclopentadienyl)erbium precursor. The RP-MOCVD approach produced highly (100)-oriented, dense, and mechanically stable Er2O3 films with columnar structure.

Demonstration of improved charge transfer in graphene/Au nanorods plasmonic hybrids stabilized by benzyl thiol linkers

Hybrids based on graphene decorated with plasmonic gold (Au) nanostructures are being investigated as possible materials combination to add to graphene functionalities of tunable plasmon resonance and enhanced absorption at selected wavelength in the visible-near-infrared region of the spectrum. Here, we report a solution drop-casting approach for fabricating stable hybrids based on chemical vapor deposition (CVD) graphene and Au nanorods, which are able to activate effective charge transfer from graphene. We demonstrate that CVD graphene functionalization by benzyl thiol (BZT) provides the linker to strong anchoring, via S-Au bonds, Au nanorods to graphene. Optical measurements by spectroscopic ellipsometry give evidence of the introduction of plasmon resonances at 1.85 and 2.25 eV in the Au nanorods/BZT/graphene hybrids, which enable surface enhanced Raman scattering (SERS) detection. Furthermore, an effective electron transfer from graphene to Au nanorods, resulting in an enhancement of p-type doping of graphene with a consequent decrease of its sheet resistance, is probed by Raman spectroscopy and corroborated by electrical measurements.

Interface and Surface Modification of ZnO Induced by Hydrogen and Nitrogen and their Impact on Optical Properties

In this contribution, we address two critical and interesting aspects from both fundamental and technological point of views, which are the polarity of ZnO and the interface reactivity and stability to hydrogen and nitrogen. The effects of atomic hydrogen and nitrogen produced by radiofrequency (r.f. ,13.56 MHz) H2 and N2 plasmas and of temperature on the optical, compositional and structural properties of Zn- and O-polar ZnO have been studied. It is found that Zn-polar ZnO is highly reactive with atomic hydrogen while O-polar ZnO is almost inert. Conversely, both polarities react with nitrogen, with the O-polar ZnO showing a larger reactivity toward N-atoms than the Zn-polarity.