Study of Graphene Growth by Gas-Source Molecular Beam Epitaxy Using Cracked Ethanol: Influence of Gas Flow Rate on Graphitic Material Deposition

Abstract

To understand what is going on during graphene growth by gas-source molecular beam epitaxy with cracked ethanol and to gain insights into how to optimize this growth method to produce high-quality graphene, we investigated the influence of gas flow rate on the growth rate. From the core-level photoelectron intensities, we found that the deposition rate decreases with increasing gas supply rate. We introduced growth efficiency using the photoelectron intensities and environmental pressure of the growth system during ethanol supply and found that the efficiency decreases with increasing supply rate. To understand this phenomenon, we supplied the cracked ethanol to the previously deposited graphitic material on the substrate and found that the graphitic material was removed from the substrate surface. These results indicate that, under the supply of cracked ethanol, deposition and etching of graphitic material occur simultaneously. This process of competitive reactions, deposition and etching, results in the extremely low growth rate, and the reactions are almost balanced at our growth condition.