This book presents the status quo of the structure, preparation, properties and applications of tetrahedrally bonded amorphous carbon (ta-C) films and compares them with related film systems. Tetrahedrally bonded amorphous carbon films (ta-C) combine some of the outstanding properties of diamond with the versatility of amorphous materials. The book compares experimental results with the predictions of theoretical analyses, condensing them to practicable rules. It is strictly application oriented, emphasizing the exceptional potential of ta-C for tribological coatings of tools and components.

World experts in amorphous carbon have been drawn together to produce this comprehensive commentary on the current state and future prospects of amorphous carbon, a highly functional material. Amorphous carbon has a wide range of properties that are primarily controlled by the different bond hybridisations possible in such materials. This allows for the growth of an extensive range of thin films that can be tailored for specific applications. Films can range from those with high transparency and which are hard and diamond-like, through to those which are opaque, soft and graphitic-like. Application areas including field emission cathodes, MEMs, electronic devices, medical and optical coatings are now close to market.

Amorphous, hydrogenated carbon (AHC) films can be deposited on various substrates using several techniques, e.g. plasma deposition and ion beam deposition. The resulting films can be hard, wear resistant and transparent.

This book presents the latest research in ultrathin carbon-based protective overcoats for high areal density magnetic data storage systems, with a particular focus on hard disk drives (HDDs) and tape drives. These findings shed new light on how the microstructure and interfacial chemistry of these sub-20 nm overcoats can be engineered at the nanoscale regime to obtain enhanced properties for wear, thermal and corrosion protection – which are critical for such applications. Readers will also be provided with fresh experimental insights into the suitability of graphene as an atomically-thin overcoat for HDD media. The easy readability of this book will appeal to a wide audience, ranging from non-specialists with a general interest in the field to scientists and industry professionals directly involved in thin film and coatings research.

Heat-assisted magnetic recording (HAMR) is a promising technology for next-generation magnetic storage devices that has the potential to increase magnetic recording density by orders of magnitude (up to 10 Tb/in2). By focusing a laser beam to rapidly heat the magnetic media above the Curie temperature, the coercivity of the magnetic domains over a small area can be sufficiently reduced to allow changes in polarization at a finer scale, thus enabling the reading and writing of data at much greater densities. Several factors, however, have prevented this technology from reaching the market. One major issue is the thermal stability of the amorphous carbon (a-C) overcoat on the magnetic head and its ability to protect critical components, such as read and write poles, near-field transducer, and waveguide, when heated to high temperatures during drive operation. This dissertation focuses on the optimization of a-C overcoats (also referred to as tetrahedral amorphous carbon (ta-C) due to the relatively high content of tetrahedral (sp3) carbon atom hybridization) deposited at very short deposition times (6 sec) and investigates the effects of heating on the nanostructure and intermixing with underlayers. As the overcoat thickness approaches only a few atomic layers, its performance and continuity become of concern, especially when exposed to higher temperatures. Since the tribomechanical and corrosion properties of carbon films have been correlated to the type of carbon atom hybridization, the choice of deposition technique and parameters to control the relative bonding content is crucial. Among the various deposition techniques, filtered cathodic vacuum arc (FCVA) was chosen to develop a-C protective overcoats. The energetic C+ ions film precursors in FCVA are especially beneficial for depositing continuous ultrathin a-C films with low surface roughness. Deposition parameters explored include the ion incidence angle and pulse substrate bias voltage under optimized duty cycle and ion fluence FCVA conditions, with the intent of minimizing a-C film thickness while maintaining adequate mechanical performance. Cross-sectional high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM) coupled with electron energy loss spectroscopy (EELS) were used to reveal nanostructure variations along the through thickness of a-C films and carbon intermixing with the substrate. The optimized coatings were deposited on an assortment adhesion (NiCr), buffer (SiN, TaOx), and base layers (Au, FeCo) common to HAMR magnetic media and heated for 30 min to simulate accumulation of heating damage. For a-C films 2-3 nm thick, the highest sp3 content was found in the bulk layer and were synthesized under FCVA deposition conditions of 65% duty cycle and -25 to -75 V substrate bias. The HRTEM and EELS analysis revealed no changes in thickness and minor structural changes in the a-C overcoat and generally small amounts of intermixing between the overcoat and the underlayers when operated in an inert hot environment. The findings of this dissertation suggest that proper optimization of such layered coatings can provide a viable solution to thermal damage of HAMR heads.