Morphology of ultrathin gold and copper coatings thermally evaporated on polydimethylsiloxane elastomers: from isolated nanoparticles to continuous coatings

International audienceThis article presents a morphological study of ultrathin gold and copper coatings (between 1 nm and 20 nm equivalent metal thickness) thermally evaporated on polydimethylsiloxane (PDMS). Results are discussed on the basis of transmission electron microscopy (TEM) and atomic force microscopy (AFM). Gold is demonstrated to grow in the form of isolated particles following a Volmer-Weber growth mode, whereas copper more likely grows in the form of a continuous film, following a Stranski-Krastanov growth mode. Our results demonstrate a negligible role of the PDMS elastic modulus (between 0.5 MPa and 2.5 MPa) in the gold and copper coatings morphology respectively. However, significant morphological changes are observed when the metals are thermally evaporated on a PDMS substrate of extremely higher surface elastic modulus obtained after O$_2$ plasma exposure

Highly n-doped graphene generated through intercalated terbium atoms

We obtained highly n-type doped graphene by intercalating terbium atoms between graphene and SiC(0001) through appropriate annealing in ultrahigh vacuum. After terbium intercalation angle-resolved-photoelectron spectroscopy (ARPES) showed a drastic change in the band structure around the K points of the Brillouin zone: the well-known conical dispersion band of a graphene monolayer was superposed by a second conical dispersion band of a graphene monolayer with an electron density reaching 10(15) cm(-2). In addition, we demonstrate that atom intercalation proceeds either below the buffer layer or between the buffer layer and the monolayer graphene. The intercalation of terbium below a pure buffer layer led to the formation of a highly n-doped graphene monolayer decoupled from the SiC substrate, as evidenced by ARPES and x-ray photoelectron spectroscopy measurements. The band structure of this highly n-doped monolayer graphene showed a kink (a deviation from the linear dispersion of the Dirac cone), which has been associated with an electron-phonon coupling constant one order of magnitude larger than those usually obtained for graphene with intercalated alkali metals