Images and characterization of nanocrystalline glass-like carbon (NGLC) films using different microscopy techniques (optical, electron microscopy and atomic force microscopy (AFM)).

<p>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 (<b>A</b>). 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 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0173978#sec002" target="_blank">Material and Methods</a>) (<b>B</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 (<b>C</b>), which replicates the structure of widely used glass-like carbons. Carbon-coated copper after CVD (<b>D</b>) and flakes of 82±37 μm length and approximately 300 nm thicknesses (<b>E</b>, <b>F</b>). 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 (<b>G</b>). Surface roughness of PMMA/Carbon film composites measured by AFM, showing increasing roughness on those with a 20- and 80-nm-thick carbon films (<b>H</b>). See also Romero et al., 2016 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0173978#pone.0173978.ref015" target="_blank">15</a>] (Doi:<a href="http://dx.doi.org/10.1016/j.cej.2016.04.005" target="_blank">10.1016/j.cej.2016.04.005</a>).</p>