Monolayer Amorphous Carbon as a 2D Barrier

Monolayer amorphous carbon (MAC) have emerged as a highly promising 2D material with exceptional properties. As the first amorphous 2D material, MAC possess a single atomic layer thickness and large area continuity over wafer scale. MAC can be synthesized conformally over a wide range of substrates at low temperatures (&lt;300 °C). Its structure consists of complete in-plane sp² bonding and is free-standing at monolayer thickness. These unique attributes give MAC a range of properties that set it apart from its crystalline counterpart, graphene, and make it a compatible material for barrier applications.<br/>This study presents research on the structural characterisation and barrier properties of atomically thin MAC films. By using laser-assisted chemical vapor deposition (LCVD), we successfully grew monolayer and multilayer MAC films, with precise control of the number of layers. By using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic resolution transmission electron microscopy (TEM), we show that MAC amorphous layered structure remains identical regardless of thickness. Multilayer MAC were found to be fully sp² bonded and lacked long-range order, exhibiting a distribution of 5-9-member carbon rings.<br/>In our investigations, we explore the potential applications of MAC across various fields as a 2D barrier layer. The direct conformal growth of MAC onto the target substrate ensures defect-free, continuous coverage over large areas. Combined with the absence of reactive grain boundaries, this gives MAC films its exceptional chemical and mechanical stability despite their sub-nanometer thickness. The stability of MAC films is highly advantageous for barrier applications, where materials must remain structurally intact and free from degradation despite being sub-nanometer thick. We demonstrate the use of MAC films as ultrathin barrier films for copper interconnects in integrated circuits to impede metal ion diffusion. The findings of this study highlight the exceptional properties of atomically thin amorphous materials to overcome existing material bottlenecks. Together with its technologically relevant growth conditions, there is immense potential for enhancing device performance and addressing prevalent technological challenges.