The paper presents research on coatings with advanced architecture, composed of a Cr/Cr₂N ceramic/metal multilayer and graded carbon layers with varying properties from Cr/a-C:H to a-C:N. The microstructure of the coatings was analysed using transmission electron microscopy and Energy Dispersive Spectroscopy, the mechanical properties were tested by nanoindentation, spherical indentation, and scratch testing, and tribological tests were also conducted. The proper selection of subsequent layers in graded coatings allowed high hardness and fracture resistance to be obtained as well as good adhesion to multilayers. Moreover, these coatings have higher wear resistance than single coatings and a friction coefficient equal to 0.25.

Flash memories are the preferred choice for data storage in portable gadgets. The charge trapping nonvolatile flash memories are the main contender to replace standard floating gate technology. In this work, we investigate metal/blocking oxide/high-k charge trapping layer/tunnel oxide/Si (MOHOS) structures from the viewpoint of their application as memory cells in charge trapping flash memories. Two different stacks, HfO₂/Al₂O₃ nanolaminates and Al-doped HfO₂, are used as the charge trapping layer, and SiO₂ (of different thickness) or Al₂O₃ is used as the tunneling oxide. The charge trapping and memory windows, and retention and endurance characteristics are studied to assess the charge storage ability of memory cells. The influence of post-deposition oxygen annealing on the memory characteristics is also studied. The results reveal that these characteristics are most strongly affected by post-deposition oxygen annealing and the type and thickness of tunneling oxide. The stacks before annealing and the 3.5 nm SiO₂ tunneling oxide have favorable charge trapping and retention properties, but their endurance is compromised because of the high electric field vulnerability. Rapid thermal annealing (RTA) in O₂ significantly increases the electron trapping (hence, the memory window) in the stacks; however, it deteriorates their retention properties, most likely due to the interfacial reaction between the tunneling oxide and the charge trapping layer. The O₂ annealing also enhances the high electric field susceptibility of the stacks, which results in better endurance. The results strongly imply that the origin of electron and hole traps is different—the hole traps are most likely related to HfO₂, while electron traps are related to Al₂O₃. These findings could serve as a useful guide for further optimization of MOHOS structures as memory cells in NVM.

Carbon fiber structures provide strength, stiffness, and fatigue resistance. Carbon-based materials show, however, significant oxidative degradation in air beginning at temperatures in the region of 400 °C. Therefore, a coating concept for carbon–carbon composites consists of an inner part, which serves as a structural link with stress compensation ability to the carbon substrate, and an outer part, which acts as a diffusion barrier. In the presented paper, chromium/chromium nitride (Cr/CrN) multilayer structure has been selected as the inner part. The outer part of the coating, in the presented paper, was hydrogenated amorphous carbon (a-C:H). Among doping metals, Cr, as one of the carbide formed elements, possesses an attractive combination of properties (corrosion resistance, wear resistance, etc.). Thus, in the presented paper, a-C:H part of the coating was implanted by Cr nanocrystals. Coatings were deposited by means of magnetron sputtering technique. They were subjected to complex investigations. Mechanisms of a mechanical wear of analyzed systems were presented, focusing on the cracking propagation in ball-on-disc tests using a 1 N and 5 N applied loads for 20 000 cycles. Complex microstructure analysis of presented nano-multilayer coatings, before and after mechanical tests, were performed by means of transmission electron microscopy (TEM). The microstructure characterization revealed that cracking, which was propagating in the outer part of the coating (in the carbon part) in the layer with lower nano-particle content, was stopped at the interface with the higher nano-particle content layer. In the case of the inner part of the coating (Cr/Cr₂N), ceramic layers showed brittle cracking, while metallic (Cr) ones deformed plastically.