Nano-engineered diamond and diamond-like carbon films for advanced electronic, photonic, and biomedical devices: Materials design, processing, and device-level insights

Diamond and diamond-like carbon (DLC) films represent a technologically versatile class of advanced carbon materials whose exceptional mechanical, thermal, optical, and chemical attributes have enabled broad applicability across electronics, photonics, tribology, sensing, and biomedical systems. Recent progress in nanoscale engineering, including controlled sp 3 /sp 2 hybridization, intentional doping, defect tailoring, plasma-assisted film growth, grain-boundary modulation, and hybrid carbon architectures, has substantially expanded their functional landscape. This review synthesizes contemporary developments in nano-engineered diamond and DLC films, beginning with a rigorous examination of atomic bonding, microstructural evolution, and the influence of nanoscale modifications on electronic, optical, and mechanical behaviour. Major deposition technologies, chemical vapor deposition (CVD), plasma-enhanced CVD, sputtering, pulsed-laser deposition, and ion-beam-based techniques, are comparatively evaluated with emphasis on sp 3 tunability, intrinsic stress control, surface termination, and interface stability. Material attributes are subsequently linked to device-level performance in high-power electronics, ultraviolet (UV) photonics, Micro-Electro-Mechanical Systems (MEMS)/Nano-Electro-Mechanical Systems (NEMS) devices, quantum sensing platforms, and biomedical coatings. Persistent barriers, including limited dopant activation, defect localization, stress management, manufacturability, and long-term durability, are critically assessed. Finally, emerging research trajectories such as diamond-graphene hybrids, engineered vacancy centres, ultra-low-temperature deposition, and multifunctional biointerfaces are highlighted. Overall, this review provides an integrated materials-to-device perspective to accelerate the development of next-generation technologies that leverage nano-engineered diamond and DLC films. • Nanoscale-engineered diamond/DLC films unified from bonding to device function. • Deposition advances enable sp 3 control, defect tuning, and stress management. • Critical barriers identified: dopants, defect localization, stress, scalability. • Emerging breakthroughs: vacancy control, hybrids, low-T growth, roll-to-roll.