Superior Adhesion of Monolayer Amorphous Carbon to Copper

The single-atom thickness of graphene holds great potential for device scaling, but its effectiveness as a thin metal-ion diffusion barrier in microelectronics and a corrosion barrier for plasmonic devices is compromised by weak van der Waals interactions with copper (Cu), leading to delamination issues. In contrast, monolayer amorphous carbon (MAC), a recently reported single-atom-thick carbon film with a disordered sp² hybridized structure, demonstrates superior adhesion properties. This study reveals that MAC exhibits an adhesion energy of 85 J m^-2 on Cu, which is 13 times greater than that of graphene. This exceptional adhesion is attributed to the formation of covalent-like Cu─C bonds while preserving its sp² structure, as evidenced by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Density functional theory (DFT) calculations further elucidate that the corrugated structure of MAC facilitates the hybridization of C 2p_z orbitals with Cu 4s and 3dz² orbitals, promoting strong bonding. These insights indicate that the amorphous structure of MAC significantly enhances adhesion while preserving its elemental composition, providing a pathway to improve the mechanical reliability and performance of two-dimensional (2D) materials on metal substrates in various technological applications.