Driving force for diamond deposition in the activated gas phase under low pressure

摘要

Diamond deposition in the activated gas phase at low pressure has been known for several decades. However, the basic understanding of diamond growth is still lacking. For example, some researchers observed the phenomenon of diamond deposition with simultaneous etching of graphite and attributed this to the preferential etching of graphite over diamond by super-equilibrium atomic hydrogen (SAH) produced by the gas activation process [1-3], but it has been recently suggested that it is a "thermodynamic paradox" [4-6]. In this letter, we compare the driving force for diamond deposition with that for graphite deposition from CH4/H2 mixtures, and develop the thermodynamic basis of diamond deposition with simultaneous etching of graphite.