Direct synthesis of graphene on silicon by reactive magnetron sputtering deposition

Abstract

In the present research, the graphene was grown directly on the Si (100) substrate by a high-power impulse reactive magnetron sputtering the copper target. The samples' structure, morphology, and composition were investigated by Raman scattering spectroscopy, atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy. The synthesis temperature, time, sample position in relation to the magnetron, and grid bias effects were studied. The graphene layer number decreased with growth temperature and distance between the sample and magnetron. The defects density in graphene decreased, and graphene crystallite size increased with synthesis temperature. These parameters were changed with lateral movement of the sample's position. The graphene layer number and defects density non-monotonically depended on the grid bias voltage. We revealed that the synthesis time, the distance between the substrate and the magnetron cathode target surface, and the grid bias voltage determine the graphene surface morphology and the shape and size of the graphene flakes. It was explained by competition between the graphene growth from the CHx species, growth activation by hydrogen, etching by hydrogen and argon ions, radiative defects creation, hydrogen atoms adsorption. The changes of the electrons, argon ions and copper atoms concentration and energy, and methane dissociation products density were taken into account. The temperature gradient and ion bombardment induced stress and their release were considered.