Search

Microstructural defects (MSDs) in graphene are a primary negative factor for the crystal quality and electrical properties of graphene and there is little knowledge about their formation. Here we report the formation mechanism of MSDs in graphene domains during the CVD growth on Cu substrate. Hydrogen-etching results show that an etched graphene hole corresponds to the position of a MSD that appears not only at the nucleation sites of graphene. Based on density-functional calculations, a hidden growth mechanism of MSDs that is driven by defects/impurities (e.g., Cu clusters/particles) on substrate surfaces is proposed. Our model indicates that the number of MSDs in a graphene domain depends on the density of surface defects on the Cu substrate and we demonstrate that MSDs in graphene can be significantly reduced by the careful substrate polishing. [ABSTRACT FROM AUTHOR]

The N-doped graphene domain is synthesized through co-growth of ammonia and methane by chemical vapor deposition (CVD). Results showed that the nitrogen concentration, defect density, and doping level increased with the decrease in growth temperature. Notably, the position of N1s main peak from X-ray photoelectron spectroscopy (XPS) showed a significant linear blueshift as the temperature decreased, indicating that the main doping nitrogen configuration gradually evolved from pyridinic N to pyrrolic N consistent with the theoretical explanation. In addition, the nitrogen configuration was not influenced by the NH 3 flow rate, which was mainly pyridinic N at the high temperature. With increasing NH 3 flow rate the redshift of the Raman peak was caused by the elongation of the C C bonds. This work presented a process to control the predominant bonding configuration of doping nitrogen by mainly choosing the growth temperature through CVD. [ABSTRACT FROM AUTHOR]