Thin Graphitic Structure Formation on Various Substrates by Gas-Source Molecular Beam Epitaxy Using Cracked Ethanol

We have studied the growth of graphene by gas-source molecular beam epitaxy, with a cracked-ethanol source. Three substrates – Si substrate with thin oxide layer, c -surface of sapphire, and graphene layers formed on SiC – were used to draw out clues to the optimum conditions for graphene growth. Raman spectroscopy and X-ray photoelectron spectroscopy analyses indicate that hardly any or fairly small amounts of graphene are formed on the Si and sapphire, although thin films of graphitic material can be formed. We estimated nominal growth rates on the three substrates and found that the growth rate on the graphene was much smaller than those on the other two substrates. We studied the growth process of graphene on graphene by reflection high-energy electron diffraction and found that two-dimensional graphene islands grew laterally but their lateral orientations were not aligned.