SYNTHESIS OF GRAPHENE VIA CHEMICAL VAPOUR DEPOSITION ON COPPER SUBSTRATES WITH DIFFERENT THICKNESSES

The quality of the grown graphene on the top side and subside of copper substrate with different thicknesses was investigated. Graphenes were grown on the 9, 25, 150 and 250 μm thickness copper substrates with Low-Pressure CVD using CH 4 process gas. Copper subtrates were investigated with XRD, XRF. Graphenes which grown on both surface of the copper substrate were characterized with Raman spectrometry. Results show that the grain size which calculated from XRD data is decreasing with increasing thickness except for 25 μm thick copper. Besides the micro-strain in the structure is increasing with thickness of substrate. Raman results show that the graphene grown on the top surface of the 9 μm thick substrate is purely single-layer. The other samples consist of not only single-layer graphene but also few-layer graphene domains. When we look at I 2D /I G ratios for samples on the top surface of coppers, the graphene doping decreases with increasing of thickness of substrate. At the same time, Graphenes on the copper subsurface have blueshift and higher FWMH values. It reveals that a tight relation between the graphene and the copper subsurface. The graphene grown on the top side of the 150 μm copper has the typical attribute of suspended single-layer graphene with the redshift of a narrow 2D peak and I 2D /I G ≈ 4. In this study, the best sample is obtained on the top surface of the 9 μm thick copper substrate. The large single-layer graphene is depend on microstrain rather than grain orientation.