“…Carbon allotropes have been utilized as major components in many different fields, such as mechanical protection, electronic devices, and energy harvesting, owing to their superior properties, including high hardness, thermal conductivity, transparency, low electrical resistivity, and chemical inertness. Because such properties are strongly influenced by the hybridization configuration of carbon atoms, it is important to understand the relationship between the hybridization structure of carbon and its properties and to find the optimum synthesis conditions for carbon films with appropriate sp 2 /sp 3 ratios. − Generally, amorphous carbon (a-C) films show higher hardness, , transparency, and thermal stability than hydrogenated amorphous carbon (a-C:H) films . This has attracted much research interest from various application fields, including lubricative or protective coating, electromagnetic wave shielding, sensors, and biology. , In addition, advances in deposition techniques, such as high-power impulse magneto sputtering (HiPIMS), − electron cyclotron resonance sputtering, and unbalanced magnetron sputtering, have facilitated the synthesis of diverse carbon nanostructures, providing greater opportunities for carbon-based applications.…”