Effects of substrate temperature and intermediate layer on adhesion, structural and mechanical properties of coaxial arc plasma deposition grown nanodiamond composite films on Si substrates

• Published in: Surface & coatings technology 2021-07, Vol.417, p.127185, Article 127185
• Main Authors: Ali, Ali M., Egiza, Mohamed, Murasawa, Koki, Sugita, Hiroaki, Deckert-Gaudig, Tanja, Deckert, Volker, Yoshitake, Tsuyoshi
• Format: Article
• Language: English
• Subjects: Adhesion; Adhesive strength; Arc deposition; Atomic interdiffusion; Coaxial arc plasma deposition; Diamonds; Film growth; Hardness; Interdiffusion; Low temperature; Mechanical properties; Miniaturization; Nanodiamond composite films; Nanostructure; Plasma deposition; Residual stress; Room temperature; Silicon; Silicon substrates
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2021.127185

Low-temperature fabrication of nanodiamond films on untreated silicon substrates, which are preferred substrates and widely employed in industry, can extend nanodiamond film applications, for instance in biosensing and miniaturization technologies. For its realization, the weak adhesion of nanodiamond films on silicon substrates due to insufficient atomic interdiffusion at the interfaces is a serious issue that needs to be overcome. In the present study, coaxial arc plasma deposition (CAPD) grown nanodiamond films were fabricated at low temperatures on silicon substrates. The effects of the substrate temperature, which is an important parameter in the CAPD nanodiamond film growth process, were structurally and physically investigated. It was found that the films softened with increasing substrate temperature and atomic interdiffusions at interfaces between the films and substrates were activated, which resulted in the formation of SiC at the interfaces. On the other hand, the films fabricated directly on silicon at room temperature were exfoliated due to the poor adhesion and high residual stress. Consequently, intermediate layers that were fabricated at elevated substrate temperatures were employed to improve the adhesion strength of nanodiamond films on silicon substrates. This way, the atomic interdiffusion at the interfaces could be promoted and the residual stress in the films was relieved. In the second stage, the films were fabricated on the intermediate layers at different temperatures. It has shown that the top layer films fabricated at low temperature gained distinctive mechanical and structural properties. By applying this strategy, several micrometres of hard nanodiamond films can be fabricated on Si substrates without easily being peeled off. [Display omitted] •Coaxial arc plasma (CAP) was used in depositing nanodiamond composite (NDC) films.•Substrate temperature is a controllable parameter in CAP NDC film growing process.•Effects of substrate temperature on mechanical and structure properties were studied.•Intermediate layers were adapted to improve interlocking and adhesion at interface.•Hard and thick NDC films were deposited on Si substrates without being peeled off.