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Graphene, a two-dimensional material of carbon atoms in a honeycomb lattice, with many extraordinary properties is used to make nano and microelectronic devices. In this study, electrical properties of extensive monolayer graphene area (1.6 × 10–2 m2) produced by chemical vapor deposition was investigated. Electrical contacts were formed by bottom-up patterning of Cr on Si3N4 insulating substrates using a wire cut stencil mask in a physical vapor deposition setup. The graphene sheet was then transferred over the electrical contacts. Surface characterization with AFM, Raman spectroscopy, TEM and electron diffraction have been effective in identifying the defects, holes, wrinkles, and the number of layers. Current–voltage and resistance characterizations were performed with an I–V measurement setup and a four-point probe system. The results show that monolayer graphene with linear/ohmic behavior is well insulated from the flat substrate regardless of the holes, wrinkles and impurities induced due to the wet transfer. The currents achieved here with Si3N4 and stencil mask, are one to two orders of magnitude larger than those obtained with SiO2 and lithographic methods presented in the literature. These signify that exploiting flatter substrates and cleaner electrode deposition methods clearly enhances electrical properties of graphene-based devices. [ABSTRACT FROM AUTHOR]

In recent years, carbon nanotubes (CNTs) have attracted great attention in the fabrication of probe tips and actuators for scanning microscopes. Herein, the pull-in instability of CNT-based probe is investigated using a nanoscale continuum model. The Euler-Bernoulli beam theory is applied to model the elastic response of the CNT. The van der Waals attraction is computed from the simplified Lennard-Jones potential. Two analytical methods (i.e., Homotopy perturbation method and Adomian decomposition method) are applied to solve the nonlinear governing equation of the system. Furthermore, the obtained results are validated by comparing with experimental results in the literature as well as numerical solutions of the finite difference method. The pull-in parameters are determined and effect of van der Waals force and a geometrical parameter effect on the instability behavior of the CNT is discussed. Moreover, the detachment length and minimum initial gap of the freestanding CNT probe are determined. PACS Nos.: 85.85.+j, 61.48.De, 46.32.+X, 45.10.-b. Ces dernieres annees, les nanotubes de carbone (CNTs) ont fortement attire l'attention pour la fabrication de pointe de sonde et d'actuateurs pour les microscopes a balayage. Nous etudions ici l'instabilite de collage d'une sonde basee sur des CNT en utilisant un modele du continuum a l'echelle nano. Nous appliquons la theorie de la poutre de Euler-Bernouilli pour modeliser la reponse elastique du CNT. Nous calculons l'attraction de van der Waals a partir d'un potentiel simplifie de Lennard- Jones. Deux methodes analytiques, a savoir la methode perturbative d'homotopie et la decomposition d'Adomian, sont utilisees pour resoudre les equations directrices non lineaires du systeme. Nous validons nos resultats en les comparant a des donnees experimentales trouvees dans la litterature et avec des resultats de calcul par elements finis. Nous determinons les parametres de collage et discutons les effets de la force de van der Waals et du parametre geometrique sur l'instabilite du CNT. Nous determinons aussi la longueur de decollement et la separation initiale minimale de la sonde CNT libre. [Traduit par la Redaction], 1. Introduction With the recent growth in nanotechnology, carbon nanotubes (CNTs) are increasingly applied in developing atomic force microscope (AFM) probe tips [1-3], nanotweezers [4], and nanoelectromechanical system (NEMS) actuators [...]