Growth and properties of few-layer graphene prepared by chemical vapor deposition

摘要

The structure, and electrical, mechanical and optical properties of few-layergraphene (FLG) synthesized by chemical vapor deposition (CVD) on a Ni coatedsubstrate were studied. Atomic resolution transmission electron microscope(TEM) images show highly crystalline single layer parts of the sample changingto multilayer domains where crystal boundaries are connected by chemical bonds.This suggests two different growth mechanisms. CVD and carbon segregationparticipate in the growth process and are responsible for the differentstructural formations found. Measurements of the electrical and mechanicalproperties on the centimeter scale provide evidence of a large scale structuralcontinuity: 1) in the temperature dependence of the electrical conductivity, anon-zero value near 0 K indicates the metallic character of electronictransport; 2) the Young's modulus of a pristine polycarbonate film (1.37 GPa)improves significantly when covered with FLG (1.85 GPa). The latter indicatesan extraordinary Young modulus value of the FLG-coating of TPa orders ofmagnitude. Raman and optical spectroscopy support the previous conclusions. Thesample can be used as a flexible and transparent electrode and is suitable forspecial membranes to detect and study individual molecules in high resolutionTEM.