The Etching Mechanisms of Diamond, Graphite, and Amorphous Carbon by Hydrogen Plasma: A Reactive Molecular Dynamics Study

Understanding how hydrogen plasma etches various potential products during the diamond growth process can contribute to improving the knowledge of diamond growth. However, due to the absence of an in situ characterization technique during the etching process, the complex chemical reactions involved in the process obscure the atomic-scale etching mechanisms. In this paper, the etching mechanisms of diamond (001), graphite (0001), and amorphous carbon substrates irradiated by hydrogen plasmas are investigated and compared using molecular dynamics simulations based on ReaxFF. When the incident energy of H atoms is 1 eV, the rate of carbon loss from graphite and amorphous carbon are far higher than that from diamond. As the incident energy of H atoms increases, the etching rate of diamond shows a slow increase, while the etching rates of amorphous carbon and graphite exhibit more significant increases. It can be concluded that the etching rate of diamond is significantly lower than that of graphite and amorphous carbon under H plasma. In the Chemical Vapor Deposition (CVD) process of diamond growth, the generated graphite and amorphous carbon are rapidly etched, leaving only diamond. This offers a plausible explanation for the growth mechanism of diamond through CVD.