Transfer of graphene to optically transparent substrates
Graphene grown by chemical vapor deposition on copper foil is transferred onto optically transparent substrates by a method using soft paraffin as scaffold during catalyst removal. After the scaffold with graphene was scooped with the target substrate, the scaffold was annealed in vacuum and then exposed to n-hexane. Soaking in n-hexane removes most of the scaffold. Raman spectroscopy unambiguously confirms that graphene was transferred on glass and c-axis cut quartz. Although residues were visible on MgO (110), no graphene signature intensities were measured, implying that the graphene film has scrolled away from the MgO surface. The transfer technique we have developed depends on the target substrate. For substrates SiO/Si, glass, and quartz, the full widths at half maximum of the 2D peak, 19-38 cm-1 shows that polycrystalline, slightly disordered single layer graphene was more likely transferred than stacked decoupled single layer graphene (FWHM 50 cm-1). The D to G peak intensities are below 0.25, showing that a low density of grain boundaries is generated by the transfer process.