Images and characterization of nanocrystalline glass-like carbon (NGLC) films using different microscopy techniques (optical, electron microscopy and atomic force microscopy (AFM)).
NGLC films with different thicknesses (~5, ~20 and ~80 nm) and baseline thermal treatment non-carbon film (BTTN) used in the experiments showing different degrees of transparency (A). The thinnest sample (~5 nm) shows the high transparency (86%) and moderately high electrical conductivity (sheet resistance: 7.8 kΩ/sq). They were obtained on a copper surface by carefully controlling the gas flow ratios used in the CVD procedure (see Material and Methods) (B). These nanostructured carbon thin films are composed of few-layer and curved graphene fragments of ~3 nm in average size joined by an amorphous carbon matrix (C), which replicates the structure of widely used glass-like carbons. Carbon-coated copper after CVD (D) and flakes of 82±37 μm length and approximately 300 nm thicknesses (E, F). Raman spectroscopy of NGLC films with different thicknesses (~5, ~20 and ~80 nm), microflakes and graphene, showing the broad spectra of amorphous carbons compared to highly crystalline graphene (G). Surface roughness of PMMA/Carbon film composites measured by AFM, showing increasing roughness on those with a 20- and 80-nm-thick carbon films (H). See also Romero et al., 2016  (Doi:10.1016/j.cej.2016.04.005).