A method includes forming ionic clusters of carbon-containing molecules, which molecules have carbon-carbon sp2 bonds, and accelerating the clusters. A surface of a substrate is irradiated with the clusters. A material is formed on the surface using the carbon from the molecules. The material includes carbon and may optionally include hydrogen. The material may include graphene. The material may form a monolayer. The molecules may include one or more material selected from the group consisting of graphene, carbon allotropes, ethylene, and hydrocarbon molecules containing ethylenic moieties. A fused region may be formed in the substrate as an interface between the substrate and the material. The clusters may have diameters of at least 20 nanometer s and may be accelerated to an energy of at least 0.5 keV.