Optimum reproduction and characterization of graphene on copper foils by low pressure chemical vapor deposition

Although the chemical vapor deposition synthesis of scalable graphene was done by many different groups, growing mechanism and optimization of graphene on copper foils has not yet been fully understood under appropriate conditions. In the context of low pressure chemical vapor deposition, annealing of copper can lead to very large and flat grains for uniform formation of monolayer graphene on copper via a combination of H₂ and CH₄ gases at a substrate temperature of 1000°C. Growing tendency of graphene domains was investigated according to different exposure time and flux of CH₄. Graphene was found not to be a uniform coverage of the whole copper surface due to inhomogeneous surface roughness among different copper grains. However, it can be improved more significantly by annealing copper up to near its melting temperature before graphene formation at lower substrate temperature of 1000°C. For this reason, we found that the thermal resistance of our materials acts as a function of the degree of graphene coverage on copper. Our graphene on copper foils was investigated by optical microscopy, Raman spectroscopy, scanning electron microscopy and heat transfer technique.